gdkpixbuf

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 Go to latest Published: Apr 5, 2024 License: MPL-2.0 Imports: 17 Imported by: 0

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Index

Constants

View Source 
const PIXBUF_MAJOR = 2

PIXBUF_MAJOR: major version of gdk-pixbuf library, that is the "0" in "0.8.2" for example.

View Source 
const PIXBUF_MICRO = 6

PIXBUF_MICRO: micro version of gdk-pixbuf library, that is the "2" in "0.8.2" for example.

View Source 
const PIXBUF_MINOR = 42

PIXBUF_MINOR: minor version of gdk-pixbuf library, that is the "8" in "0.8.2" for example.

View Source 
const PIXBUF_VERSION = "2.42.6"

PIXBUF_VERSION contains the full version of GdkPixbuf as a string.

This is the version being compiled against; contrast with gdk_pixbuf_version.

Variables

View Source 
var (
	GTypeColorspace           = coreglib.Type(C.gdk_colorspace_get_type())
	GTypeInterpType           = coreglib.Type(C.gdk_interp_type_get_type())
	GTypePixbufAlphaMode      = coreglib.Type(C.gdk_pixbuf_alpha_mode_get_type())
	GTypePixbufError          = coreglib.Type(C.gdk_pixbuf_error_get_type())
	GTypePixbufRotation       = coreglib.Type(C.gdk_pixbuf_rotation_get_type())
	GTypePixbuf               = coreglib.Type(C.gdk_pixbuf_get_type())
	GTypePixbufAnimation      = coreglib.Type(C.gdk_pixbuf_animation_get_type())
	GTypePixbufAnimationIter  = coreglib.Type(C.gdk_pixbuf_animation_iter_get_type())
	GTypePixbufLoader         = coreglib.Type(C.gdk_pixbuf_loader_get_type())
	GTypePixbufSimpleAnim     = coreglib.Type(C.gdk_pixbuf_simple_anim_get_type())
	GTypePixbufSimpleAnimIter = coreglib.Type(C.gdk_pixbuf_simple_anim_iter_get_type())
	GTypePixbufFormat         = coreglib.Type(C.gdk_pixbuf_format_get_type())
)

GType values.

Functions

func NewPixbufAnimationFromStreamAsync 

func NewPixbufAnimationFromStreamAsync(ctx context.Context, stream gio.InputStreamer, callback gio.AsyncReadyCallback)

NewPixbufAnimationFromStreamAsync creates a new animation by asynchronously loading an image from an input stream.

For more details see gdk_pixbuf_new_from_stream(), which is the synchronous version of this function.

When the operation is finished, callback will be called in the main thread. You can then call gdk_pixbuf_animation_new_from_stream_finish() to get the result of the operation.

The function takes the following parameters:

  • ctx (optional): optional #GCancellable object.
  • stream from which to load the animation.
  • callback (optional): GAsyncReadyCallback to call when the pixbuf is loaded.

func NewPixbufFromStreamAsync 

func NewPixbufFromStreamAsync(ctx context.Context, stream gio.InputStreamer, callback gio.AsyncReadyCallback)

NewPixbufFromStreamAsync creates a new pixbuf by asynchronously loading an image from an input stream.

For more details see gdk_pixbuf_new_from_stream(), which is the synchronous version of this function.

When the operation is finished, callback will be called in the main thread. You can then call gdk_pixbuf_new_from_stream_finish() to get the result of the operation.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • stream: GInputStream from which to load the pixbuf.
  • callback (optional): GAsyncReadyCallback to call when the pixbuf is loaded.

func NewPixbufFromStreamAtScaleAsync 

func NewPixbufFromStreamAtScaleAsync(ctx context.Context, stream gio.InputStreamer, width, height int, preserveAspectRatio bool, callback gio.AsyncReadyCallback)

NewPixbufFromStreamAtScaleAsync creates a new pixbuf by asynchronously loading an image from an input stream.

For more details see gdk_pixbuf_new_from_stream_at_scale(), which is the synchronous version of this function.

When the operation is finished, callback will be called in the main thread. You can then call gdk_pixbuf_new_from_stream_finish() to get the result of the operation.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • stream: GInputStream from which to load the pixbuf.
  • width the image should have or -1 to not constrain the width.
  • height the image should have or -1 to not constrain the height.
  • preserveAspectRatio: TRUE to preserve the image's aspect ratio.
  • callback (optional): GAsyncReadyCallback to call when the pixbuf is loaded.

func PixbufCalculateRowstride 

func PixbufCalculateRowstride(colorspace Colorspace, hasAlpha bool, bitsPerSample, width, height int) int

PixbufCalculateRowstride calculates the rowstride that an image created with those values would have.

This function is useful for front-ends and backends that want to check image values without needing to create a GdkPixbuf.

The function takes the following parameters:

  • colorspace: color space for image.
  • hasAlpha: whether the image should have transparency information.
  • bitsPerSample: number of bits per color sample.
  • width: width of image in pixels, must be > 0.
  • height: height of image in pixels, must be > 0.

The function returns the following values:

  • gint: rowstride for the given values, or -1 in case of error.

func PixbufErrorQuark 

func PixbufErrorQuark() glib.Quark

The function returns the following values:

func PixbufGetFileInfoAsync 

func PixbufGetFileInfoAsync(ctx context.Context, filename string, callback gio.AsyncReadyCallback)

PixbufGetFileInfoAsync: asynchronously parses an image file far enough to determine its format and size.

For more details see gdk_pixbuf_get_file_info(), which is the synchronous version of this function.

When the operation is finished, callback will be called in the main thread. You can then call gdk_pixbuf_get_file_info_finish() to get the result of the operation.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • filename: name of the file to identify.
  • callback (optional): GAsyncReadyCallback to call when the file info is available.

func PixbufInitModules 

func PixbufInitModules(path string) error

PixbufInitModules initalizes the gdk-pixbuf loader modules referenced by the loaders.cache file present inside that directory.

This is to be used by applications that want to ship certain loaders in a different location from the system ones.

This is needed when the OS or runtime ships a minimal number of loaders so as to reduce the potential attack surface of carefully crafted image files, especially for uncommon file types. Applications that require broader image file types coverage, such as image viewers, would be expected to ship the gdk-pixbuf modules in a separate location, bundled with the application in a separate directory from the OS or runtime- provided modules.

The function takes the following parameters:

  • path: path to directory where the loaders.cache is installed.

func PixbufSaveToStreamFinish 

func PixbufSaveToStreamFinish(asyncResult gio.AsyncResulter) error

PixbufSaveToStreamFinish finishes an asynchronous pixbuf save operation started with gdk_pixbuf_save_to_stream_async().

The function takes the following parameters:

  • asyncResult: GAsyncResult.

Types

type Colorspace 

type Colorspace C.gint

Colorspace: this enumeration defines the color spaces that are supported by the gdk-pixbuf library.

Currently only RGB is supported. 

const (
	// ColorspaceRGB indicates a red/green/blue additive color space.
	ColorspaceRGB Colorspace = iota
)

func (Colorspace) String 

func (c Colorspace) String() string

String returns the name in string for Colorspace.

type InterpType 

type InterpType C.gint

InterpType: interpolation modes for scaling functions.

The GDK_INTERP_NEAREST mode is the fastest scaling method, but has horrible quality when scaling down; GDK_INTERP_BILINEAR is the best choice if you aren't sure what to choose, it has a good speed/quality balance.

**Note**: Cubic filtering is missing from the list; hyperbolic interpolation is just as fast and results in higher quality. 

const (
	// InterpNearest: nearest neighbor sampling; this is the fastest and lowest
	// quality mode. Quality is normally unacceptable when scaling down, but may
	// be OK when scaling up.
	InterpNearest InterpType = iota
	// InterpTiles: this is an accurate simulation of the PostScript image
	// operator without any interpolation enabled. Each pixel is rendered as a
	// tiny parallelogram of solid color, the edges of which are implemented
	// with antialiasing. It resembles nearest neighbor for enlargement,
	// and bilinear for reduction.
	InterpTiles
	// InterpBilinear: best quality/speed balance; use this mode by default.
	// Bilinear interpolation. For enlargement, it is equivalent to
	// point-sampling the ideal bilinear-interpolated image. For reduction,
	// it is equivalent to laying down small tiles and integrating over the
	// coverage area.
	InterpBilinear
	// InterpHyper: this is the slowest and highest quality reconstruction
	// function. It is derived from the hyperbolic filters in Wolberg's "Digital
	// Image Warping", and is formally defined as the hyperbolic-filter sampling
	// the ideal hyperbolic-filter interpolated image (the filter is designed to
	// be idempotent for 1:1 pixel mapping). **Deprecated**: this interpolation
	// filter is deprecated, as in reality it has a lower quality than the
	// GDK_INTERP_BILINEAR filter (Since: 2.38).
	InterpHyper
)

func (InterpType) String 

func (i InterpType) String() string

String returns the name in string for InterpType.

type Pixbuf 

type Pixbuf struct {
	*coreglib.Object

	gio.LoadableIcon
	// contains filtered or unexported fields
}

Pixbuf: pixel buffer.

GdkPixbuf contains information about an image's pixel data, its color space, bits per sample, width and height, and the rowstride (the number of bytes between the start of one row and the start of the next).

Creating new GdkPixbuf

The most basic way to create a pixbuf is to wrap an existing pixel buffer with a gdkpixbuf.Pixbuf instance. You can use the gdkpixbuf.Pixbuf.NewFromData function to do this.

Every time you create a new GdkPixbuf instance for some data, you will need to specify the destroy notification function that will be called when the data buffer needs to be freed; this will happen when a GdkPixbuf is finalized by the reference counting functions. If you have a chunk of static data compiled into your application, you can pass in NULL as the destroy notification function so that the data will not be freed.

The gdkpixbuf.Pixbuf.New constructor function can be used as a convenience to create a pixbuf with an empty buffer; this is equivalent to allocating a data buffer using malloc() and then wrapping it with gdk_pixbuf_new_from_data(). The gdk_pixbuf_new() function will compute an optimal rowstride so that rendering can be performed with an efficient algorithm.

As a special case, you can use the gdkpixbuf.Pixbuf.NewFromXPMData function to create a pixbuf from inline XPM image data.

You can also copy an existing pixbuf with the pixbuf.Copy function. This is not the same as just acquiring a reference to the old pixbuf instance: the copy function will actually duplicate the pixel data in memory and create a new pixbuf instance for it.

Reference counting

GdkPixbuf structures are reference counted. This means that an application can share a single pixbuf among many parts of the code. When a piece of the program needs to use a pixbuf, it should acquire a reference to it by calling g_object_ref(); when it no longer needs the pixbuf, it should release the reference it acquired by calling g_object_unref(). The resources associated with a GdkPixbuf will be freed when its reference count drops to zero. Newly-created GdkPixbuf instances start with a reference count of one.

Image Data

Image data in a pixbuf is stored in memory in an uncompressed, packed format. Rows in the image are stored top to bottom, and in each row pixels are stored from left to right.

There may be padding at the end of a row.

The "rowstride" value of a pixbuf, as returned by gdkpixbuf.Pixbuf.GetRowstride(), indicates the number of bytes between rows.

**NOTE**: If you are copying raw pixbuf data with memcpy() note that the last row in the pixbuf may not be as wide as the full rowstride, but rather just as wide as the pixel data needs to be; that is: it is unsafe to do memcpy (dest, pixels, rowstride * height) to copy a whole pixbuf. Use gdkpixbuf.Pixbuf.Copy() instead, or compute the width in bytes of the last row as: 

last_row = width * ((n_channels * bits_per_sample + 7) / 8);

The same rule applies when iterating over each row of a GdkPixbuf pixels array.

The following code illustrates a simple put_pixel() function for RGB pixbufs with 8 bits per channel with an alpha channel. 

static void
put_pixel (GdkPixbuf *pixbuf,
           int x,
	   int y,
	   guchar red,
	   guchar green,
	   guchar blue,
	   guchar alpha)
{
  int n_channels = gdk_pixbuf_get_n_channels (pixbuf);

  // Ensure that the pixbuf is valid
  g_assert (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB);
  g_assert (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8);
  g_assert (gdk_pixbuf_get_has_alpha (pixbuf));
  g_assert (n_channels == 4);

  int width = gdk_pixbuf_get_width (pixbuf);
  int height = gdk_pixbuf_get_height (pixbuf);

  // Ensure that the coordinates are in a valid range
  g_assert (x >= 0 && x < width);
  g_assert (y >= 0 && y < height);

  int rowstride = gdk_pixbuf_get_rowstride (pixbuf);

  // The pixel buffer in the GdkPixbuf instance
  guchar *pixels = gdk_pixbuf_get_pixels (pixbuf);

  // The pixel we wish to modify
  guchar *p = pixels + y * rowstride + x * n_channels;
  p[0] = red;
  p[1] = green;
  p[2] = blue;
  p[3] = alpha;
}

Loading images

The GdkPixBuf class provides a simple mechanism for loading an image from a file in synchronous and asynchronous fashion.

For GUI applications, it is recommended to use the asynchronous stream API to avoid blocking the control flow of the application.

Additionally, GdkPixbuf provides the gdkpixbuf.PixbufLoader` API for progressive image loading.

Saving images

The GdkPixbuf class provides methods for saving image data in a number of file formats. The formatted data can be written to a file or to a memory buffer. GdkPixbuf can also call a user-defined callback on the data, which allows to e.g. write the image to a socket or store it in a database.

func NewPixbuf 

func NewPixbuf(colorspace Colorspace, hasAlpha bool, bitsPerSample, width, height int) *Pixbuf

NewPixbuf creates a new GdkPixbuf structure and allocates a buffer for it.

If the allocation of the buffer failed, this function will return NULL.

The buffer has an optimal rowstride. Note that the buffer is not cleared; you will have to fill it completely yourself.

The function takes the following parameters:

  • colorspace: color space for image.
  • hasAlpha: whether the image should have transparency information.
  • bitsPerSample: number of bits per color sample.
  • width: width of image in pixels, must be > 0.
  • height: height of image in pixels, must be > 0.

The function returns the following values:

  • pixbuf (optional): newly-created pixel buffer.

func NewPixbufFromBytes 

func NewPixbufFromBytes(data *glib.Bytes, colorspace Colorspace, hasAlpha bool, bitsPerSample, width, height, rowstride int) *Pixbuf

NewPixbufFromBytes creates a new Pixbuf out of in-memory readonly image data.

Currently only RGB images with 8 bits per sample are supported.

This is the GBytes variant of gdk_pixbuf_new_from_data(), useful for language bindings.

The function takes the following parameters:

  • data: image data in 8-bit/sample packed format inside a #GBytes.
  • colorspace: colorspace for the image data.
  • hasAlpha: whether the data has an opacity channel.
  • bitsPerSample: number of bits per sample.
  • width: width of the image in pixels, must be > 0.
  • height: height of the image in pixels, must be > 0.
  • rowstride: distance in bytes between row starts.

The function returns the following values:

  • pixbuf: newly-created pixbuf.

func NewPixbufFromFile 

func NewPixbufFromFile(filename string) (*Pixbuf, error)

NewPixbufFromFile creates a new pixbuf by loading an image from a file.

The file format is detected automatically.

If NULL is returned, then error will be set. Possible errors are:

  • the file could not be opened
  • there is no loader for the file's format
  • there is not enough memory to allocate the image buffer
  • the image buffer contains invalid data

The error domains are GDK_PIXBUF_ERROR and G_FILE_ERROR.

The function takes the following parameters:

  • filename: name of file to load, in the GLib file name encoding.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromFileAtScale 

func NewPixbufFromFileAtScale(filename string, width, height int, preserveAspectRatio bool) (*Pixbuf, error)

NewPixbufFromFileAtScale creates a new pixbuf by loading an image from a file.

The file format is detected automatically.

If NULL is returned, then error will be set. Possible errors are:

  • the file could not be opened
  • there is no loader for the file's format
  • there is not enough memory to allocate the image buffer
  • the image buffer contains invalid data

The error domains are GDK_PIXBUF_ERROR and G_FILE_ERROR.

The image will be scaled to fit in the requested size, optionally preserving the image's aspect ratio.

When preserving the aspect ratio, a width of -1 will cause the image to be scaled to the exact given height, and a height of -1 will cause the image to be scaled to the exact given width. When not preserving aspect ratio, a width or height of -1 means to not scale the image at all in that dimension. Negative values for width and height are allowed since 2.8.

The function takes the following parameters:

  • filename: name of file to load, in the GLib file name encoding.
  • width the image should have or -1 to not constrain the width.
  • height the image should have or -1 to not constrain the height.
  • preserveAspectRatio: TRUE to preserve the image's aspect ratio.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromFileAtSize 

func NewPixbufFromFileAtSize(filename string, width, height int) (*Pixbuf, error)

NewPixbufFromFileAtSize creates a new pixbuf by loading an image from a file.

The file format is detected automatically.

If NULL is returned, then error will be set. Possible errors are:

  • the file could not be opened
  • there is no loader for the file's format
  • there is not enough memory to allocate the image buffer
  • the image buffer contains invalid data

The error domains are GDK_PIXBUF_ERROR and G_FILE_ERROR.

The image will be scaled to fit in the requested size, preserving the image's aspect ratio. Note that the returned pixbuf may be smaller than width x height, if the aspect ratio requires it. To load and image at the requested size, regardless of aspect ratio, use gdkpixbuf.Pixbuf.NewFromFileAtScale.

The function takes the following parameters:

  • filename: name of file to load, in the GLib file name encoding.
  • width the image should have or -1 to not constrain the width.
  • height the image should have or -1 to not constrain the height.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromImage 

func NewPixbufFromImage(img image.Image) *Pixbuf

NewPixbufFromImage creates a new Pixbuf from a stdlib image.Image. It contains a fast path for *image.RGBA while resorting to copying/converting the image otherwise.

func NewPixbufFromInline deprecated 

func NewPixbufFromInline(data []byte, copyPixels bool) (*Pixbuf, error)

NewPixbufFromInline creates a GdkPixbuf from a flat representation that is suitable for storing as inline data in a program.

This is useful if you want to ship a program with images, but don't want to depend on any external files.

GdkPixbuf ships with a program called gdk-pixbuf-csource, which allows for conversion of GdkPixbufs into such a inline representation.

In almost all cases, you should pass the --raw option to gdk-pixbuf-csource. A sample invocation would be: 

gdk-pixbuf-csource --raw --name=myimage_inline myimage.png

For the typical case where the inline pixbuf is read-only static data, you don't need to copy the pixel data unless you intend to write to it, so you can pass FALSE for copy_pixels. If you pass --rle to gdk-pixbuf-csource, a copy will be made even if copy_pixels is FALSE, so using this option is generally a bad idea.

If you create a pixbuf from const inline data compiled into your program, it's probably safe to ignore errors and disable length checks, since things will always succeed: 

pixbuf = gdk_pixbuf_new_from_inline (-1, myimage_inline, FALSE, NULL);

For non-const inline data, you could get out of memory. For untrusted inline data located at runtime, you could have corrupt inline data in addition.

Deprecated: Use GResource instead.

The function takes the following parameters:

  • data: byte data containing a serialized GdkPixdata structure.
  • copyPixels: whether to copy the pixel data, or use direct pointers data for the resulting pixbuf.

The function returns the following values:

  • pixbuf: newly-created pixbuf.

func NewPixbufFromResource 

func NewPixbufFromResource(resourcePath string) (*Pixbuf, error)

NewPixbufFromResource creates a new pixbuf by loading an image from an resource.

The file format is detected automatically. If NULL is returned, then error will be set.

The function takes the following parameters:

  • resourcePath: path of the resource file.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromResourceAtScale 

func NewPixbufFromResourceAtScale(resourcePath string, width, height int, preserveAspectRatio bool) (*Pixbuf, error)

NewPixbufFromResourceAtScale creates a new pixbuf by loading an image from an resource.

The file format is detected automatically. If NULL is returned, then error will be set.

The image will be scaled to fit in the requested size, optionally preserving the image's aspect ratio. When preserving the aspect ratio, a width of -1 will cause the image to be scaled to the exact given height, and a height of -1 will cause the image to be scaled to the exact given width. When not preserving aspect ratio, a width or height of -1 means to not scale the image at all in that dimension.

The stream is not closed.

The function takes the following parameters:

  • resourcePath: path of the resource file.
  • width the image should have or -1 to not constrain the width.
  • height the image should have or -1 to not constrain the height.
  • preserveAspectRatio: TRUE to preserve the image's aspect ratio.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromStream 

func NewPixbufFromStream(ctx context.Context, stream gio.InputStreamer) (*Pixbuf, error)

NewPixbufFromStream creates a new pixbuf by loading an image from an input stream.

The file format is detected automatically.

If NULL is returned, then error will be set.

The cancellable can be used to abort the operation from another thread. If the operation was cancelled, the error G_IO_ERROR_CANCELLED will be returned. Other possible errors are in the GDK_PIXBUF_ERROR and G_IO_ERROR domains.

The stream is not closed.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • stream: GInputStream to load the pixbuf from.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromStreamAtScale 

func NewPixbufFromStreamAtScale(ctx context.Context, stream gio.InputStreamer, width, height int, preserveAspectRatio bool) (*Pixbuf, error)

NewPixbufFromStreamAtScale creates a new pixbuf by loading an image from an input stream.

The file format is detected automatically. If NULL is returned, then error will be set. The cancellable can be used to abort the operation from another thread. If the operation was cancelled, the error G_IO_ERROR_CANCELLED will be returned. Other possible errors are in the GDK_PIXBUF_ERROR and G_IO_ERROR domains.

The image will be scaled to fit in the requested size, optionally preserving the image's aspect ratio.

When preserving the aspect ratio, a width of -1 will cause the image to be scaled to the exact given height, and a height of -1 will cause the image to be scaled to the exact given width. If both width and height are given, this function will behave as if the smaller of the two values is passed as -1.

When not preserving aspect ratio, a width or height of -1 means to not scale the image at all in that dimension.

The stream is not closed.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • stream: GInputStream to load the pixbuf from.
  • width the image should have or -1 to not constrain the width.
  • height the image should have or -1 to not constrain the height.
  • preserveAspectRatio: TRUE to preserve the image's aspect ratio.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func NewPixbufFromStreamFinish 

func NewPixbufFromStreamFinish(asyncResult gio.AsyncResulter) (*Pixbuf, error)

NewPixbufFromStreamFinish finishes an asynchronous pixbuf creation operation started with gdk_pixbuf_new_from_stream_async().

The function takes the following parameters:

  • asyncResult: GAsyncResult.

The function returns the following values:

  • pixbuf (optional): newly created pixbuf.

func NewPixbufFromXPMData 

func NewPixbufFromXPMData(data []string) *Pixbuf

NewPixbufFromXPMData creates a new pixbuf by parsing XPM data in memory.

This data is commonly the result of including an XPM file into a program's C source.

The function takes the following parameters:

  • data: pointer to inline XPM data.

The function returns the following values:

  • pixbuf: newly-created pixbuf.

func (*Pixbuf) AddAlpha 

func (pixbuf *Pixbuf) AddAlpha(substituteColor bool, r, g, b byte) *Pixbuf

AddAlpha takes an existing pixbuf and adds an alpha channel to it.

If the existing pixbuf already had an alpha channel, the channel values are copied from the original; otherwise, the alpha channel is initialized to 255 (full opacity).

If substitute_color is TRUE, then the color specified by the (r, g, b) arguments will be assigned zero opacity. That is, if you pass (255, 255, 255) for the substitute color, all white pixels will become fully transparent.

If substitute_color is FALSE, then the (r, g, b) arguments will be ignored.

The function takes the following parameters:

  • substituteColor: whether to set a color to zero opacity.
  • r: red value to substitute.
  • g: green value to substitute.
  • b: blue value to substitute.

The function returns the following values:

  • ret: newly-created pixbuf.

func (*Pixbuf) ApplyEmbeddedOrientation 

func (src *Pixbuf) ApplyEmbeddedOrientation() *Pixbuf

ApplyEmbeddedOrientation takes an existing pixbuf and checks for the presence of an associated "orientation" option.

The orientation option may be provided by the JPEG loader (which reads the exif orientation tag) or the TIFF loader (which reads the TIFF orientation tag, and compensates it for the partial transforms performed by libtiff).

If an orientation option/tag is present, the appropriate transform will be performed so that the pixbuf is oriented correctly.

The function returns the following values:

  • pixbuf (optional): newly-created pixbuf.

func (*Pixbuf) BitsPerSample 

func (pixbuf *Pixbuf) BitsPerSample() int

BitsPerSample queries the number of bits per color sample in a pixbuf.

The function returns the following values:

  • gint: number of bits per color sample.

func (*Pixbuf) ByteLength 

func (pixbuf *Pixbuf) ByteLength() uint

ByteLength returns the length of the pixel data, in bytes.

The function returns the following values:

  • gsize: length of the pixel data.

func (*Pixbuf) Colorspace 

func (pixbuf *Pixbuf) Colorspace() Colorspace

Colorspace queries the color space of a pixbuf.

The function returns the following values:

  • colorspace: color space.

func (*Pixbuf) Composite 

func (src *Pixbuf) Composite(dest *Pixbuf, destX, destY, destWidth, destHeight int, offsetX, offsetY, scaleX, scaleY float64, interpType InterpType, overallAlpha int)

Composite creates a transformation of the source image src by scaling by scale_x and scale_y then translating by offset_x and offset_y.

This gives an image in the coordinates of the destination pixbuf. The rectangle (dest_x, dest_y, dest_width, dest_height) is then alpha blended onto the corresponding rectangle of the original destination image.

When the destination rectangle contains parts not in the source image, the data at the edges of the source image is replicated to infinity.

! (composite.png).

The function takes the following parameters:

  • dest into which to render the results.
  • destX: left coordinate for region to render.
  • destY: top coordinate for region to render.
  • destWidth: width of the region to render.
  • destHeight: height of the region to render.
  • offsetX: offset in the X direction (currently rounded to an integer).
  • offsetY: offset in the Y direction (currently rounded to an integer).
  • scaleX: scale factor in the X direction.
  • scaleY: scale factor in the Y direction.
  • interpType: interpolation type for the transformation.
  • overallAlpha: overall alpha for source image (0..255).

func (*Pixbuf) CompositeColor 

func (src *Pixbuf) CompositeColor(dest *Pixbuf, destX, destY, destWidth, destHeight int, offsetX, offsetY, scaleX, scaleY float64, interpType InterpType, overallAlpha, checkX, checkY, checkSize int, color1, color2 uint32)

CompositeColor creates a transformation of the source image src by scaling by scale_x and scale_y then translating by offset_x and offset_y, then alpha blends the rectangle (dest_x ,dest_y, dest_width, dest_height) of the resulting image with a checkboard of the colors color1 and color2 and renders it onto the destination image.

If the source image has no alpha channel, and overall_alpha is 255, a fast path is used which omits the alpha blending and just performs the scaling.

See gdk_pixbuf_composite_color_simple() for a simpler variant of this function suitable for many tasks.

The function takes the following parameters:

  • dest into which to render the results.
  • destX: left coordinate for region to render.
  • destY: top coordinate for region to render.
  • destWidth: width of the region to render.
  • destHeight: height of the region to render.
  • offsetX: offset in the X direction (currently rounded to an integer).
  • offsetY: offset in the Y direction (currently rounded to an integer).
  • scaleX: scale factor in the X direction.
  • scaleY: scale factor in the Y direction.
  • interpType: interpolation type for the transformation.
  • overallAlpha: overall alpha for source image (0..255).
  • checkX: x offset for the checkboard (origin of checkboard is at -check_x, -check_y).
  • checkY: y offset for the checkboard.
  • checkSize: size of checks in the checkboard (must be a power of two).
  • color1: color of check at upper left.
  • color2: color of the other check.

func (*Pixbuf) CompositeColorSimple 

func (src *Pixbuf) CompositeColorSimple(destWidth, destHeight int, interpType InterpType, overallAlpha, checkSize int, color1, color2 uint32) *Pixbuf

CompositeColorSimple creates a new pixbuf by scaling src to dest_width x dest_height and alpha blending the result with a checkboard of colors color1 and color2.

The function takes the following parameters:

  • destWidth: width of destination image.
  • destHeight: height of destination image.
  • interpType: interpolation type for the transformation.
  • overallAlpha: overall alpha for source image (0..255).
  • checkSize: size of checks in the checkboard (must be a power of two).
  • color1: color of check at upper left.
  • color2: color of the other check.

The function returns the following values:

  • pixbuf (optional): new pixbuf.

func (*Pixbuf) Copy 

func (pixbuf *Pixbuf) Copy() *Pixbuf

Copy creates a new GdkPixbuf with a copy of the information in the specified pixbuf.

Note that this does not copy the options set on the original GdkPixbuf, use gdk_pixbuf_copy_options() for this.

The function returns the following values:

  • ret (optional): newly-created pixbuf.

func (*Pixbuf) CopyArea 

func (srcPixbuf *Pixbuf) CopyArea(srcX, srcY, width, height int, destPixbuf *Pixbuf, destX, destY int)

CopyArea copies a rectangular area from src_pixbuf to dest_pixbuf.

Conversion of pixbuf formats is done automatically.

If the source rectangle overlaps the destination rectangle on the same pixbuf, it will be overwritten during the copy operation. Therefore, you can not use this function to scroll a pixbuf.

The function takes the following parameters:

  • srcX: source X coordinate within src_pixbuf.
  • srcY: source Y coordinate within src_pixbuf.
  • width: width of the area to copy.
  • height: height of the area to copy.
  • destPixbuf: destination pixbuf.
  • destX: x coordinate within dest_pixbuf.
  • destY: y coordinate within dest_pixbuf.

func (*Pixbuf) CopyOptions 

func (srcPixbuf *Pixbuf) CopyOptions(destPixbuf *Pixbuf) bool

CopyOptions copies the key/value pair options attached to a GdkPixbuf to another GdkPixbuf.

This is useful to keep original metadata after having manipulated a file. However be careful to remove metadata which you've already applied, such as the "orientation" option after rotating the image.

The function takes the following parameters:

  • destPixbuf: destination pixbuf.

The function returns the following values:

  • ok: TRUE on success.

func (*Pixbuf) Fill 

func (pixbuf *Pixbuf) Fill(pixel uint32)

Fill clears a pixbuf to the given RGBA value, converting the RGBA value into the pixbuf's pixel format.

The alpha component will be ignored if the pixbuf doesn't have an alpha channel.

The function takes the following parameters:

  • pixel: RGBA pixel to used to clear (0xffffffff is opaque white, 0x00000000 transparent black).

func (*Pixbuf) Flip 

func (src *Pixbuf) Flip(horizontal bool) *Pixbuf

Flip flips a pixbuf horizontally or vertically and returns the result in a new pixbuf.

The function takes the following parameters:

  • horizontal: TRUE to flip horizontally, FALSE to flip vertically.

The function returns the following values:

  • pixbuf (optional): new pixbuf.

func (*Pixbuf) HasAlpha 

func (pixbuf *Pixbuf) HasAlpha() bool

HasAlpha queries whether a pixbuf has an alpha channel (opacity information).

The function returns the following values:

  • ok: TRUE if it has an alpha channel, FALSE otherwise.

func (*Pixbuf) Height 

func (pixbuf *Pixbuf) Height() int

Height queries the height of a pixbuf.

The function returns the following values:

  • gint: height in pixels.

func (*Pixbuf) NChannels 

func (pixbuf *Pixbuf) NChannels() int

NChannels queries the number of channels of a pixbuf.

The function returns the following values:

  • gint: number of channels.

func (*Pixbuf) NewSubpixbuf 

func (srcPixbuf *Pixbuf) NewSubpixbuf(srcX, srcY, width, height int) *Pixbuf

NewSubpixbuf creates a new pixbuf which represents a sub-region of src_pixbuf.

The new pixbuf shares its pixels with the original pixbuf, so writing to one affects both. The new pixbuf holds a reference to src_pixbuf, so src_pixbuf will not be finalized until the new pixbuf is finalized.

Note that if src_pixbuf is read-only, this function will force it to be mutable.

The function takes the following parameters:

  • srcX: x coord in src_pixbuf.
  • srcY: y coord in src_pixbuf.
  • width of region in src_pixbuf.
  • height of region in src_pixbuf.

The function returns the following values:

  • pixbuf: new pixbuf.

func (*Pixbuf) Option 

func (pixbuf *Pixbuf) Option(key string) string

Option looks up key in the list of options that may have been attached to the pixbuf when it was loaded, or that may have been attached by another function using gdk_pixbuf_set_option().

For instance, the ANI loader provides "Title" and "Artist" options. The ICO, XBM, and XPM loaders provide "x_hot" and "y_hot" hot-spot options for cursor definitions. The PNG loader provides the tEXt ancillary chunk key/value pairs as options. Since 2.12, the TIFF and JPEG loaders return an "orientation" option string that corresponds to the embedded TIFF/Exif orientation tag (if present). Since 2.32, the TIFF loader sets the "multipage" option string to "yes" when a multi-page TIFF is loaded. Since 2.32 the JPEG and PNG loaders set "x-dpi" and "y-dpi" if the file contains image density information in dots per inch. Since 2.36.6, the JPEG loader sets the "comment" option with the comment EXIF tag.

The function takes the following parameters:

  • key: nul-terminated string.

The function returns the following values:

  • utf8 (optional): value associated with key.

func (*Pixbuf) Options 

func (pixbuf *Pixbuf) Options() map[string]string

Options returns a GHashTable with a list of all the options that may have been attached to the pixbuf when it was loaded, or that may have been attached by another function using gdkpixbuf.Pixbuf.SetOption().

The function returns the following values:

  • hashTable: Table of key/values pairs.

func (*Pixbuf) Pixels 

func (pixbuf *Pixbuf) Pixels() []byte

Pixels queries a pointer to the pixel data of a pixbuf.

This function will cause an implicit copy of the pixbuf data if the pixbuf was created from read-only data.

Please see the section on image data (#image-data) for information about how the pixel data is stored in memory.

The function returns the following values:

  • guint8s: pointer to the pixbuf's pixel data.

func (*Pixbuf) ReadPixelBytes 

func (pixbuf *Pixbuf) ReadPixelBytes() *glib.Bytes

ReadPixelBytes provides a #GBytes buffer containing the raw pixel data; the data must not be modified.

This function allows skipping the implicit copy that must be made if gdk_pixbuf_get_pixels() is called on a read-only pixbuf.

The function returns the following values:

  • bytes: new reference to a read-only copy of the pixel data. Note that for mutable pixbufs, this function will incur a one-time copy of the pixel data for conversion into the returned #GBytes.

func (*Pixbuf) ReadPixels 

func (pixbuf *Pixbuf) ReadPixels() *byte

ReadPixels provides a read-only pointer to the raw pixel data.

This function allows skipping the implicit copy that must be made if gdk_pixbuf_get_pixels() is called on a read-only pixbuf.

The function returns the following values:

  • guint8: read-only pointer to the raw pixel data.

func (*Pixbuf) RemoveOption 

func (pixbuf *Pixbuf) RemoveOption(key string) bool

RemoveOption removes the key/value pair option attached to a GdkPixbuf.

The function takes the following parameters:

  • key: nul-terminated string representing the key to remove.

The function returns the following values:

  • ok: TRUE if an option was removed, FALSE if not.

func (*Pixbuf) RotateSimple 

func (src *Pixbuf) RotateSimple(angle PixbufRotation) *Pixbuf

RotateSimple rotates a pixbuf by a multiple of 90 degrees, and returns the result in a new pixbuf.

If angle is 0, this function will return a copy of src.

The function takes the following parameters:

  • angle to rotate by.

The function returns the following values:

  • pixbuf (optional): new pixbuf.

func (*Pixbuf) Rowstride 

func (pixbuf *Pixbuf) Rowstride() int

Rowstride queries the rowstride of a pixbuf, which is the number of bytes between the start of a row and the start of the next row.

The function returns the following values:

  • gint: distance between row starts.

func (*Pixbuf) SaturateAndPixelate 

func (src *Pixbuf) SaturateAndPixelate(dest *Pixbuf, saturation float32, pixelate bool)

SaturateAndPixelate modifies saturation and optionally pixelates src, placing the result in dest.

The src and dest pixbufs must have the same image format, size, and rowstride.

The src and dest arguments may be the same pixbuf with no ill effects.

If saturation is 1.0 then saturation is not changed. If it's less than 1.0, saturation is reduced (the image turns toward grayscale); if greater than 1.0, saturation is increased (the image gets more vivid colors).

If pixelate is TRUE, then pixels are faded in a checkerboard pattern to create a pixelated image.

The function takes the following parameters:

  • dest: place to write modified version of src.
  • saturation factor.
  • pixelate: whether to pixelate.

func (*Pixbuf) SaveToBufferv 

func (pixbuf *Pixbuf) SaveToBufferv(typ string, optionKeys, optionValues []string) ([]byte, error)

SaveToBufferv: vector version of gdk_pixbuf_save_to_buffer().

Saves pixbuf to a new buffer in format type, which is currently "jpeg", "tiff", "png", "ico" or "bmp".

See gdkpixbuf.Pixbuf.SaveToBuffer() for more details.

The function takes the following parameters:

  • typ: name of file format.
  • optionKeys (optional): name of options to set.
  • optionValues (optional) values for named options.

The function returns the following values:

  • buffer: location to receive a pointer to the new buffer.

func (*Pixbuf) SaveToCallbackv 

func (pixbuf *Pixbuf) SaveToCallbackv(saveFunc PixbufSaveFunc, typ string, optionKeys, optionValues []string) error

SaveToCallbackv: vector version of gdk_pixbuf_save_to_callback().

Saves pixbuf to a callback in format type, which is currently "jpeg", "png", "tiff", "ico" or "bmp".

If error is set, FALSE will be returned.

See gdkpixbuf.Pixbuf.SaveToCallback() for more details.

The function takes the following parameters:

  • saveFunc: function that is called to save each block of data that the save routine generates.
  • typ: name of file format.
  • optionKeys (optional): name of options to set.
  • optionValues (optional) values for named options.

func (*Pixbuf) SaveToStreamv 

func (pixbuf *Pixbuf) SaveToStreamv(ctx context.Context, stream gio.OutputStreamer, typ string, optionKeys, optionValues []string) error

SaveToStreamv saves pixbuf to an output stream.

Supported file formats are currently "jpeg", "tiff", "png", "ico" or "bmp".

See gdkpixbuf.Pixbuf.SaveToStream() for more details.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • stream: GOutputStream to save the pixbuf to.
  • typ: name of file format.
  • optionKeys (optional): name of options to set.
  • optionValues (optional) values for named options.

func (*Pixbuf) SaveToStreamvAsync 

func (pixbuf *Pixbuf) SaveToStreamvAsync(ctx context.Context, stream gio.OutputStreamer, typ string, optionKeys, optionValues []string, callback gio.AsyncReadyCallback)

SaveToStreamvAsync saves pixbuf to an output stream asynchronously.

For more details see gdk_pixbuf_save_to_streamv(), which is the synchronous version of this function.

When the operation is finished, callback will be called in the main thread.

You can then call gdk_pixbuf_save_to_stream_finish() to get the result of the operation.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object, NULL to ignore.
  • stream: GOutputStream to which to save the pixbuf.
  • typ: name of file format.
  • optionKeys (optional): name of options to set.
  • optionValues (optional) values for named options.
  • callback (optional): GAsyncReadyCallback to call when the pixbuf is saved.

func (*Pixbuf) Savev 

func (pixbuf *Pixbuf) Savev(filename, typ string, optionKeys, optionValues []string) error

Savev: vector version of gdk_pixbuf_save().

Saves pixbuf to a file in type, which is currently "jpeg", "png", "tiff", "ico" or "bmp".

If error is set, FALSE will be returned.

See gdkpixbuf.Pixbuf.Save() for more details.

The function takes the following parameters:

  • filename: name of file to save.
  • typ: name of file format.
  • optionKeys (optional): name of options to set.
  • optionValues (optional) values for named options.

func (*Pixbuf) Scale 

func (src *Pixbuf) Scale(dest *Pixbuf, destX, destY, destWidth, destHeight int, offsetX, offsetY, scaleX, scaleY float64, interpType InterpType)

Scale creates a transformation of the source image src by scaling by scale_x and scale_y then translating by offset_x and offset_y, then renders the rectangle (dest_x, dest_y, dest_width, dest_height) of the resulting image onto the destination image replacing the previous contents.

Try to use gdk_pixbuf_scale_simple() first; this function is the industrial-strength power tool you can fall back to, if gdk_pixbuf_scale_simple() isn't powerful enough.

If the source rectangle overlaps the destination rectangle on the same pixbuf, it will be overwritten during the scaling which results in rendering artifacts.

The function takes the following parameters:

  • dest into which to render the results.
  • destX: left coordinate for region to render.
  • destY: top coordinate for region to render.
  • destWidth: width of the region to render.
  • destHeight: height of the region to render.
  • offsetX: offset in the X direction (currently rounded to an integer).
  • offsetY: offset in the Y direction (currently rounded to an integer).
  • scaleX: scale factor in the X direction.
  • scaleY: scale factor in the Y direction.
  • interpType: interpolation type for the transformation.

func (*Pixbuf) ScaleSimple 

func (src *Pixbuf) ScaleSimple(destWidth, destHeight int, interpType InterpType) *Pixbuf

ScaleSimple: create a new pixbuf containing a copy of src scaled to dest_width x dest_height.

This function leaves src unaffected.

The interp_type should be GDK_INTERP_NEAREST if you want maximum speed (but when scaling down GDK_INTERP_NEAREST is usually unusably ugly). The default interp_type should be GDK_INTERP_BILINEAR which offers reasonable quality and speed.

You can scale a sub-portion of src by creating a sub-pixbuf pointing into src; see gdkpixbuf.Pixbuf.NewSubpixbuf().

If dest_width and dest_height are equal to the width and height of src, this function will return an unscaled copy of src.

For more complicated scaling/alpha blending see gdkpixbuf.Pixbuf.Scale() and gdkpixbuf.Pixbuf.Composite().

The function takes the following parameters:

  • destWidth: width of destination image.
  • destHeight: height of destination image.
  • interpType: interpolation type for the transformation.

The function returns the following values:

  • pixbuf (optional): new pixbuf.

func (*Pixbuf) SetOption 

func (pixbuf *Pixbuf) SetOption(key, value string) bool

SetOption attaches a key/value pair as an option to a GdkPixbuf.

If key already exists in the list of options attached to the pixbuf, the new value is ignored and FALSE is returned.

The function takes the following parameters:

  • key: nul-terminated string.
  • value: nul-terminated string.

The function returns the following values:

  • ok: TRUE on success.

func (*Pixbuf) Width 

func (pixbuf *Pixbuf) Width() int

Width queries the width of a pixbuf.

The function returns the following values:

  • gint: width in pixels.

type PixbufAlphaMode deprecated 

type PixbufAlphaMode C.gint

PixbufAlphaMode: control the alpha channel for drawables.

These values can be passed to gdk_pixbuf_xlib_render_to_drawable_alpha() in gdk-pixbuf-xlib to control how the alpha channel of an image should be handled.

This function can create a bilevel clipping mask (black and white) and use it while painting the image.

In the future, when the X Window System gets an alpha channel extension, it will be possible to do full alpha compositing onto arbitrary drawables. For now both cases fall back to a bilevel clipping mask.

Deprecated: There is no user of GdkPixbufAlphaMode in GdkPixbuf, and the Xlib utility functions have been split out to their own library, gdk-pixbuf-xlib. 

const (
	// PixbufAlphaBilevel: bilevel clipping mask (black and white) will be
	// created and used to draw the image. Pixels below 0.5 opacity will be
	// considered fully transparent, and all others will be considered fully
	// opaque.
	PixbufAlphaBilevel PixbufAlphaMode = iota
	// PixbufAlphaFull: for now falls back to K_PIXBUF_ALPHA_BILEVEL. In the
	// future it will do full alpha compositing.
	PixbufAlphaFull
)

func (PixbufAlphaMode) String 

func (p PixbufAlphaMode) String() string

String returns the name in string for PixbufAlphaMode.

type PixbufAnimation 

type PixbufAnimation struct {
	*coreglib.Object
	// contains filtered or unexported fields
}

PixbufAnimation: opaque object representing an animation.

The GdkPixBuf library provides a simple mechanism to load and represent animations. An animation is conceptually a series of frames to be displayed over time.

The animation may not be represented as a series of frames internally; for example, it may be stored as a sprite and instructions for moving the sprite around a background.

To display an animation you don't need to understand its representation, however; you just ask GdkPixbuf what should be displayed at a given point in time.

func NewPixbufAnimationFromFile 

func NewPixbufAnimationFromFile(filename string) (*PixbufAnimation, error)

NewPixbufAnimationFromFile creates a new animation by loading it from a file.

The file format is detected automatically.

If the file's format does not support multi-frame images, then an animation with a single frame will be created.

Possible errors are in the GDK_PIXBUF_ERROR and G_FILE_ERROR domains.

The function takes the following parameters:

  • filename: name of file to load, in the GLib file name encoding.

The function returns the following values:

  • pixbufAnimation (optional): newly-created animation.

func NewPixbufAnimationFromResource 

func NewPixbufAnimationFromResource(resourcePath string) (*PixbufAnimation, error)

NewPixbufAnimationFromResource creates a new pixbuf animation by loading an image from an resource.

The file format is detected automatically. If NULL is returned, then error will be set.

The function takes the following parameters:

  • resourcePath: path of the resource file.

The function returns the following values:

  • pixbufAnimation (optional): newly-created animation.

func NewPixbufAnimationFromStream 

func NewPixbufAnimationFromStream(ctx context.Context, stream gio.InputStreamer) (*PixbufAnimation, error)

NewPixbufAnimationFromStream creates a new animation by loading it from an input stream.

The file format is detected automatically.

If NULL is returned, then error will be set.

The cancellable can be used to abort the operation from another thread. If the operation was cancelled, the error G_IO_ERROR_CANCELLED will be returned. Other possible errors are in the GDK_PIXBUF_ERROR and G_IO_ERROR domains.

The stream is not closed.

The function takes the following parameters:

  • ctx (optional): optional GCancellable object.
  • stream: GInputStream to load the pixbuf from.

The function returns the following values:

  • pixbufAnimation (optional): newly-created animation.

func NewPixbufAnimationFromStreamFinish 

func NewPixbufAnimationFromStreamFinish(asyncResult gio.AsyncResulter) (*PixbufAnimation, error)

NewPixbufAnimationFromStreamFinish finishes an asynchronous pixbuf animation creation operation started with gdkpixbuf.PixbufAnimation().NewFromStreamAsync.

The function takes the following parameters:

  • asyncResult: Result.

The function returns the following values:

  • pixbufAnimation (optional): newly created animation.

func (*PixbufAnimation) Height 

func (animation *PixbufAnimation) Height() int

Height queries the height of the bounding box of a pixbuf animation.

The function returns the following values:

  • gint: height of the bounding box of the animation.

func (*PixbufAnimation) IsStaticImage 

func (animation *PixbufAnimation) IsStaticImage() bool

IsStaticImage checks whether the animation is a static image.

If you load a file with gdk_pixbuf_animation_new_from_file() and it turns out to be a plain, unanimated image, then this function will return TRUE. Use gdk_pixbuf_animation_get_static_image() to retrieve the image.

The function returns the following values:

  • ok: TRUE if the "animation" was really just an image.

func (*PixbufAnimation) Iter 

func (animation *PixbufAnimation) Iter(startTime *glib.TimeVal) *PixbufAnimationIter

Iter: get an iterator for displaying an animation.

The iterator provides the frames that should be displayed at a given time.

start_time would normally come from g_get_current_time(), and marks the beginning of animation playback. After creating an iterator, you should immediately display the pixbuf returned by gdk_pixbuf_animation_iter_get_pixbuf(). Then, you should install a timeout (with g_timeout_add()) or by some other mechanism ensure that you'll update the image after gdk_pixbuf_animation_iter_get_delay_time() milliseconds. Each time the image is updated, you should reinstall the timeout with the new, possibly-changed delay time.

As a shortcut, if start_time is NULL, the result of g_get_current_time() will be used automatically.

To update the image (i.e. possibly change the result of gdk_pixbuf_animation_iter_get_pixbuf() to a new frame of the animation), call gdk_pixbuf_animation_iter_advance().

If you're using PixbufLoader, in addition to updating the image after the delay time, you should also update it whenever you receive the area_updated signal and gdk_pixbuf_animation_iter_on_currently_loading_frame() returns TRUE. In this case, the frame currently being fed into the loader has received new data, so needs to be refreshed. The delay time for a frame may also be modified after an area_updated signal, for example if the delay time for a frame is encoded in the data after the frame itself. So your timeout should be reinstalled after any area_updated signal.

A delay time of -1 is possible, indicating "infinite".

The function takes the following parameters:

  • startTime (optional): time when the animation starts playing.

The function returns the following values:

  • pixbufAnimationIter: iterator to move over the animation.

func (*PixbufAnimation) StaticImage 

func (animation *PixbufAnimation) StaticImage() *Pixbuf

StaticImage retrieves a static image for the animation.

If an animation is really just a plain image (has only one frame), this function returns that image.

If the animation is an animation, this function returns a reasonable image to use as a static unanimated image, which might be the first frame, or something more sophisticated depending on the file format.

If an animation hasn't loaded any frames yet, this function will return NULL.

The function returns the following values:

  • pixbuf: unanimated image representing the animation.

func (*PixbufAnimation) Width 

func (animation *PixbufAnimation) Width() int

Width queries the width of the bounding box of a pixbuf animation.

The function returns the following values:

  • gint: width of the bounding box of the animation.

type PixbufAnimationIter 

type PixbufAnimationIter struct {
	*coreglib.Object
	// contains filtered or unexported fields
}

PixbufAnimationIter: opaque object representing an iterator which points to a certain position in an animation.

func (*PixbufAnimationIter) Advance 

func (iter *PixbufAnimationIter) Advance(currentTime *glib.TimeVal) bool

Advance: possibly advances an animation to a new frame.

Chooses the frame based on the start time passed to gdk_pixbuf_animation_get_iter().

current_time would normally come from g_get_current_time(), and must be greater than or equal to the time passed to gdk_pixbuf_animation_get_iter(), and must increase or remain unchanged each time gdk_pixbuf_animation_iter_get_pixbuf() is called. That is, you can't go backward in time; animations only play forward.

As a shortcut, pass NULL for the current time and g_get_current_time() will be invoked on your behalf. So you only need to explicitly pass current_time if you're doing something odd like playing the animation at double speed.

If this function returns FALSE, there's no need to update the animation display, assuming the display had been rendered prior to advancing; if TRUE, you need to call gdk_pixbuf_animation_iter_get_pixbuf() and update the display with the new pixbuf.

The function takes the following parameters:

  • currentTime (optional): current time.

The function returns the following values:

  • ok: TRUE if the image may need updating.

func (*PixbufAnimationIter) DelayTime 

func (iter *PixbufAnimationIter) DelayTime() int

DelayTime gets the number of milliseconds the current pixbuf should be displayed, or -1 if the current pixbuf should be displayed forever.

The g_timeout_add() function conveniently takes a timeout in milliseconds, so you can use a timeout to schedule the next update.

Note that some formats, like GIF, might clamp the timeout values in the image file to avoid updates that are just too quick. The minimum timeout for GIF images is currently 20 milliseconds.

The function returns the following values:

  • gint: delay time in milliseconds (thousandths of a second).

func (*PixbufAnimationIter) OnCurrentlyLoadingFrame 

func (iter *PixbufAnimationIter) OnCurrentlyLoadingFrame() bool

OnCurrentlyLoadingFrame: used to determine how to respond to the area_updated signal on PixbufLoader when loading an animation.

The ::area_updated signal is emitted for an area of the frame currently streaming in to the loader. So if you're on the currently loading frame, you will need to redraw the screen for the updated area.

The function returns the following values:

  • ok: TRUE if the frame we're on is partially loaded, or the last frame.

func (*PixbufAnimationIter) Pixbuf 

func (iter *PixbufAnimationIter) Pixbuf() *Pixbuf

Pixbuf gets the current pixbuf which should be displayed.

The pixbuf might not be the same size as the animation itself (gdk_pixbuf_animation_get_width(), gdk_pixbuf_animation_get_height()).

This pixbuf should be displayed for gdk_pixbuf_animation_iter_get_delay_time() milliseconds.

The caller of this function does not own a reference to the returned pixbuf; the returned pixbuf will become invalid when the iterator advances to the next frame, which may happen anytime you call gdk_pixbuf_animation_iter_advance().

Copy the pixbuf to keep it (don't just add a reference), as it may get recycled as you advance the iterator.

The function returns the following values:

  • pixbuf to be displayed.

type PixbufError 

type PixbufError C.gint

PixbufError: error code in the GDK_PIXBUF_ERROR domain.

Many gdk-pixbuf operations can cause errors in this domain, or in the G_FILE_ERROR domain. 

const (
	// PixbufErrorCorruptImage: image file was broken somehow.
	PixbufErrorCorruptImage PixbufError = iota
	// PixbufErrorInsufficientMemory: not enough memory.
	PixbufErrorInsufficientMemory
	// PixbufErrorBadOption: bad option was passed to a pixbuf save module.
	PixbufErrorBadOption
	// PixbufErrorUnknownType: unknown image type.
	PixbufErrorUnknownType
	// PixbufErrorUnsupportedOperation: don't know how to perform the given
	// operation on the type of image at hand.
	PixbufErrorUnsupportedOperation
	// PixbufErrorFailed: generic failure code, something went wrong.
	PixbufErrorFailed
	// PixbufErrorIncompleteAnimation: only part of the animation was loaded.
	PixbufErrorIncompleteAnimation
)

func (PixbufError) String 

func (p PixbufError) String() string

String returns the name in string for PixbufError.

type PixbufFormat 

type PixbufFormat struct {
	// contains filtered or unexported fields
}

PixbufFormat: GdkPixbufFormat contains information about the image format accepted by a module.

Only modules should access the fields directly, applications should use the gdk_pixbuf_format_* family of functions.

An instance of this type is always passed by reference.

func PixbufGetFileInfo 

func PixbufGetFileInfo(filename string) (width, height int, pixbufFormat *PixbufFormat)

PixbufGetFileInfo parses an image file far enough to determine its format and size.

The function takes the following parameters:

  • filename: name of the file to identify.

The function returns the following values:

  • width (optional): return location for the width of the image.
  • height (optional): return location for the height of the image.
  • pixbufFormat (optional): GdkPixbufFormat describing the image format of the file.

func PixbufGetFileInfoFinish 

func PixbufGetFileInfoFinish(asyncResult gio.AsyncResulter) (width, height int, pixbufFormat *PixbufFormat, goerr error)

PixbufGetFileInfoFinish finishes an asynchronous pixbuf parsing operation started with gdk_pixbuf_get_file_info_async().

The function takes the following parameters:

  • asyncResult: GAsyncResult.

The function returns the following values:

  • width: return location for the width of the image, or NULL.
  • height: return location for the height of the image, or NULL.
  • pixbufFormat (optional): GdkPixbufFormat describing the image format of the file.

func PixbufGetFormats 

func PixbufGetFormats() []*PixbufFormat

PixbufGetFormats obtains the available information about the image formats supported by GdkPixbuf.

The function returns the following values:

  • sList: list of support image formats.

func (*PixbufFormat) Copy 

func (format *PixbufFormat) Copy() *PixbufFormat

Copy creates a copy of format.

The function returns the following values:

  • pixbufFormat: newly allocated copy of a GdkPixbufFormat. Use gdk_pixbuf_format_free() to free the resources when done.

func (*PixbufFormat) Description 

func (format *PixbufFormat) Description() string

Description returns a description of the format.

The function returns the following values:

  • utf8: description of the format.

func (*PixbufFormat) Extensions 

func (format *PixbufFormat) Extensions() []string

Extensions returns the filename extensions typically used for files in the given format.

The function returns the following values:

  • utf8s: array of filename extensions.

func (*PixbufFormat) IsDisabled 

func (format *PixbufFormat) IsDisabled() bool

IsDisabled returns whether this image format is disabled.

See gdk_pixbuf_format_set_disabled().

The function returns the following values:

  • ok: whether this image format is disabled.

func (*PixbufFormat) IsSaveOptionSupported 

func (format *PixbufFormat) IsSaveOptionSupported(optionKey string) bool

IsSaveOptionSupported returns TRUE if the save option specified by option_key is supported when saving a pixbuf using the module implementing format.

See gdk_pixbuf_save() for more information about option keys.

The function takes the following parameters:

  • optionKey: name of an option.

The function returns the following values:

  • ok: TRUE if the specified option is supported.

func (*PixbufFormat) IsScalable 

func (format *PixbufFormat) IsScalable() bool

IsScalable returns whether this image format is scalable.

If a file is in a scalable format, it is preferable to load it at the desired size, rather than loading it at the default size and scaling the resulting pixbuf to the desired size.

The function returns the following values:

  • ok: whether this image format is scalable.

func (*PixbufFormat) IsWritable 

func (format *PixbufFormat) IsWritable() bool

IsWritable returns whether pixbufs can be saved in the given format.

The function returns the following values:

  • ok: whether pixbufs can be saved in the given format.

func (*PixbufFormat) License 

func (format *PixbufFormat) License() string

License returns information about the license of the image loader for the format.

The returned string should be a shorthand for a well known license, e.g. "LGPL", "GPL", "QPL", "GPL/QPL", or "other" to indicate some other license.

The function returns the following values:

  • utf8: string describing the license of the pixbuf format.

func (*PixbufFormat) MIMETypes 

func (format *PixbufFormat) MIMETypes() []string

MIMETypes returns the mime types supported by the format.

The function returns the following values:

  • utf8s: array of mime types.

func (*PixbufFormat) Name 

func (format *PixbufFormat) Name() string

Name returns the name of the format.

The function returns the following values:

  • utf8: name of the format.

func (*PixbufFormat) SetDisabled 

func (format *PixbufFormat) SetDisabled(disabled bool)

SetDisabled disables or enables an image format.

If a format is disabled, GdkPixbuf won't use the image loader for this format to load images.

Applications can use this to avoid using image loaders with an inappropriate license, see gdk_pixbuf_format_get_license().

The function takes the following parameters:

  • disabled: TRUE to disable the format format.

type PixbufFormatFlags 

type PixbufFormatFlags C.guint

PixbufFormatFlags flags which allow a module to specify further details about the supported operations. 

const (
	// PixbufFormatWritable: module can write out images in the format.
	PixbufFormatWritable PixbufFormatFlags = 0b1
	// PixbufFormatScalable: image format is scalable.
	PixbufFormatScalable PixbufFormatFlags = 0b10
	// PixbufFormatThreadsafe: module is threadsafe. gdk-pixbuf ignores modules
	// that are not marked as threadsafe. (Since 2.28).
	PixbufFormatThreadsafe PixbufFormatFlags = 0b100
)

func (PixbufFormatFlags) Has 

func (p PixbufFormatFlags) Has(other PixbufFormatFlags) bool

Has returns true if p contains other.

func (PixbufFormatFlags) String 

func (p PixbufFormatFlags) String() string

String returns the names in string for PixbufFormatFlags.

type PixbufLoader 

type PixbufLoader struct {
	*coreglib.Object
	// contains filtered or unexported fields
}

PixbufLoader: incremental image loader.

GdkPixbufLoader provides a way for applications to drive the process of loading an image, by letting them send the image data directly to the loader instead of having the loader read the data from a file. Applications can use this functionality instead of gdk_pixbuf_new_from_file() or gdk_pixbuf_animation_new_from_file() when they need to parse image data in small chunks. For example, it should be used when reading an image from a (potentially) slow network connection, or when loading an extremely large file.

To use GdkPixbufLoader to load an image, create a new instance, and call gdkpixbuf.PixbufLoader.Write() to send the data to it. When done, gdkpixbuf.PixbufLoader.Close() should be called to end the stream and finalize everything.

The loader will emit three important signals throughout the process:

  • gdkpixbuf.PixbufLoader::size-prepared will be emitted as soon as the image has enough information to determine the size of the image to be used. If you want to scale the image while loading it, you can call gdkpixbuf.PixbufLoader.SetSize() in response to this signal.
  • gdkpixbuf.PixbufLoader::area-prepared will be emitted as soon as the pixbuf of the desired has been allocated. You can obtain the GdkPixbuf instance by calling gdkpixbuf.PixbufLoader.GetPixbuf(). If you want to use it, simply acquire a reference to it. You can also call gdk_pixbuf_loader_get_pixbuf() later to get the same pixbuf.
  • gdkpixbuf.PixbufLoader::area-updated will be emitted every time a region is updated. This way you can update a partially completed image. Note that you do not know anything about the completeness of an image from the updated area. For example, in an interlaced image you will need to make several passes before the image is done loading.

Loading an animation

Loading an animation is almost as easy as loading an image. Once the first gdkpixbuf.PixbufLoader::area-prepared signal has been emitted, you can call gdkpixbuf.PixbufLoader.GetAnimation() to get the gdkpixbuf.PixbufAnimation instance, and then call and gdkpixbuf.PixbufAnimation.GetIter() to get a gdkpixbuf.PixbufAnimationIter to retrieve the pixbuf for the desired time stamp.

func NewPixbufLoader 

func NewPixbufLoader() *PixbufLoader

NewPixbufLoader creates a new pixbuf loader object.

The function returns the following values:

  • pixbufLoader: newly-created pixbuf loader.

func NewPixbufLoaderWithMIMEType 

func NewPixbufLoaderWithMIMEType(mimeType string) (*PixbufLoader, error)

NewPixbufLoaderWithMIMEType creates a new pixbuf loader object that always attempts to parse image data as if it were an image of MIME type mime_type, instead of identifying the type automatically.

This function is useful if you want an error if the image isn't the expected MIME type; for loading image formats that can't be reliably identified by looking at the data; or if the user manually forces a specific MIME type.

The list of supported mime types depends on what image loaders are installed, but typically "image/png", "image/jpeg", "image/gif", "image/tiff" and "image/x-xpixmap" are among the supported mime types. To obtain the full list of supported mime types, call gdk_pixbuf_format_get_mime_types() on each of the PixbufFormat structs returned by gdk_pixbuf_get_formats().

The function takes the following parameters:

  • mimeType: mime type to be loaded.

The function returns the following values:

  • pixbufLoader: newly-created pixbuf loader.

func NewPixbufLoaderWithType 

func NewPixbufLoaderWithType(imageType string) (*PixbufLoader, error)

NewPixbufLoaderWithType creates a new pixbuf loader object that always attempts to parse image data as if it were an image of type image_type, instead of identifying the type automatically.

This function is useful if you want an error if the image isn't the expected type; for loading image formats that can't be reliably identified by looking at the data; or if the user manually forces a specific type.

The list of supported image formats depends on what image loaders are installed, but typically "png", "jpeg", "gif", "tiff" and "xpm" are among the supported formats. To obtain the full list of supported image formats, call gdk_pixbuf_format_get_name() on each of the PixbufFormat structs returned by gdk_pixbuf_get_formats().

The function takes the following parameters:

  • imageType: name of the image format to be loaded with the image.

The function returns the following values:

  • pixbufLoader: newly-created pixbuf loader.

func (*PixbufLoader) Animation 

func (loader *PixbufLoader) Animation() *PixbufAnimation

Animation queries the PixbufAnimation that a pixbuf loader is currently creating.

In general it only makes sense to call this function after the gdkpixbuf.PixbufLoader::area-prepared signal has been emitted by the loader.

If the loader doesn't have enough bytes yet, and hasn't emitted the area-prepared signal, this function will return NULL.

The function returns the following values:

  • pixbufAnimation (optional): animation that the loader is currently loading.

func (*PixbufLoader) Close 

func (loader *PixbufLoader) Close() error

Close informs a pixbuf loader that no further writes with gdk_pixbuf_loader_write() will occur, so that it can free its internal loading structures.

This function also tries to parse any data that hasn't yet been parsed; if the remaining data is partial or corrupt, an error will be returned.

If FALSE is returned, error will be set to an error from the GDK_PIXBUF_ERROR or G_FILE_ERROR domains.

If you're just cancelling a load rather than expecting it to be finished, passing NULL for error to ignore it is reasonable.

Remember that this function does not release a reference on the loader, so you will need to explicitly release any reference you hold.

func (*PixbufLoader) ConnectAreaPrepared 

func (loader *PixbufLoader) ConnectAreaPrepared(f func()) coreglib.SignalHandle

ConnectAreaPrepared: this signal is emitted when the pixbuf loader has allocated the pixbuf in the desired size.

After this signal is emitted, applications can call gdk_pixbuf_loader_get_pixbuf() to fetch the partially-loaded pixbuf.

func (*PixbufLoader) ConnectAreaUpdated 

func (loader *PixbufLoader) ConnectAreaUpdated(f func(x, y, width, height int)) coreglib.SignalHandle

ConnectAreaUpdated: this signal is emitted when a significant area of the image being loaded has been updated.

Normally it means that a complete scanline has been read in, but it could be a different area as well.

Applications can use this signal to know when to repaint areas of an image that is being loaded.

func (*PixbufLoader) ConnectClosed 

func (loader *PixbufLoader) ConnectClosed(f func()) coreglib.SignalHandle

ConnectClosed: this signal is emitted when gdk_pixbuf_loader_close() is called.

It can be used by different parts of an application to receive notification when an image loader is closed by the code that drives it.

func (*PixbufLoader) ConnectSizePrepared 

func (loader *PixbufLoader) ConnectSizePrepared(f func(width, height int)) coreglib.SignalHandle

ConnectSizePrepared: this signal is emitted when the pixbuf loader has been fed the initial amount of data that is required to figure out the size of the image that it will create.

Applications can call gdk_pixbuf_loader_set_size() in response to this signal to set the desired size to which the image should be scaled.

func (*PixbufLoader) Format 

func (loader *PixbufLoader) Format() *PixbufFormat

Format obtains the available information about the format of the currently loading image file.

The function returns the following values:

  • pixbufFormat (optional): PixbufFormat.

func (*PixbufLoader) Pixbuf 

func (loader *PixbufLoader) Pixbuf() *Pixbuf

Pixbuf queries the Pixbuf that a pixbuf loader is currently creating.

In general it only makes sense to call this function after the gdkpixbuf.PixbufLoader::area-prepared signal has been emitted by the loader; this means that enough data has been read to know the size of the image that will be allocated.

If the loader has not received enough data via gdk_pixbuf_loader_write(), then this function returns NULL.

The returned pixbuf will be the same in all future calls to the loader, so if you want to keep using it, you should acquire a reference to it.

Additionally, if the loader is an animation, it will return the "static image" of the animation (see gdk_pixbuf_animation_get_static_image()).

The function returns the following values:

  • pixbuf (optional) that the loader is creating.

func (*PixbufLoader) SetSize 

func (loader *PixbufLoader) SetSize(width, height int)

SetSize causes the image to be scaled while it is loaded.

The desired image size can be determined relative to the original size of the image by calling gdk_pixbuf_loader_set_size() from a signal handler for the ::size-prepared signal.

Attempts to set the desired image size are ignored after the emission of the ::size-prepared signal.

The function takes the following parameters:

  • width: desired width of the image being loaded.
  • height: desired height of the image being loaded.

func (*PixbufLoader) Write 

func (loader *PixbufLoader) Write(buf []byte) error

Write parses the next count bytes in the given image buffer.

The function takes the following parameters:

  • buf: pointer to image data.

func (*PixbufLoader) WriteBytes 

func (loader *PixbufLoader) WriteBytes(buffer *glib.Bytes) error

WriteBytes parses the next contents of the given image buffer.

The function takes the following parameters:

  • buffer: image data as a GBytes buffer.

type PixbufLoaderClass 

type PixbufLoaderClass struct {
	// contains filtered or unexported fields
}

PixbufLoaderClass: instance of this type is always passed by reference.

type PixbufLoaderOverrides 

type PixbufLoaderOverrides struct {
	AreaPrepared func()
	// The function takes the following parameters:
	//
	//   - x
	//   - y
	//   - width
	//   - height
	//
	AreaUpdated func(x, y, width, height int)
	Closed      func()
	// The function takes the following parameters:
	//
	//   - width
	//   - height
	//
	SizePrepared func(width, height int)
}

PixbufLoaderOverrides contains methods that are overridable.

type PixbufModulePreparedFunc 

type PixbufModulePreparedFunc func(pixbuf *Pixbuf, anim *PixbufAnimation)

PixbufModulePreparedFunc defines the type of the function that gets called once the initial setup of pixbuf is done.

PixbufLoader uses a function of this type to emit the "<link linkend="GdkPixbufLoader-area-prepared">area_prepared</link>" signal.

type PixbufModuleSizeFunc 

type PixbufModuleSizeFunc func(width, height *int)

PixbufModuleSizeFunc defines the type of the function that gets called once the size of the loaded image is known.

The function is expected to set width and height to the desired size to which the image should be scaled. If a module has no efficient way to achieve the desired scaling during the loading of the image, it may either ignore the size request, or only approximate it - gdk-pixbuf will then perform the required scaling on the completely loaded image.

If the function sets width or height to zero, the module should interpret this as a hint that it will be closed soon and shouldn't allocate further resources. This convention is used to implement gdk_pixbuf_get_file_info() efficiently.

type PixbufModuleUpdatedFunc 

type PixbufModuleUpdatedFunc func(pixbuf *Pixbuf, x, y, width, height int)

PixbufModuleUpdatedFunc defines the type of the function that gets called every time a region of pixbuf is updated.

PixbufLoader uses a function of this type to emit the "<link linkend="GdkPixbufLoader-area-updated">area_updated</link>" signal.

type PixbufRotation 

type PixbufRotation C.gint

PixbufRotation: possible rotations which can be passed to gdk_pixbuf_rotate_simple().

To make them easier to use, their numerical values are the actual degrees. 

const (
	// PixbufRotateNone: no rotation.
	PixbufRotateNone PixbufRotation = 0
	// PixbufRotateCounterclockwise: rotate by 90 degrees.
	PixbufRotateCounterclockwise PixbufRotation = 90
	// PixbufRotateUpsidedown: rotate by 180 degrees.
	PixbufRotateUpsidedown PixbufRotation = 180
	// PixbufRotateClockwise: rotate by 270 degrees.
	PixbufRotateClockwise PixbufRotation = 270
)

func (PixbufRotation) String 

func (p PixbufRotation) String() string

String returns the name in string for PixbufRotation.

type PixbufSaveFunc 

type PixbufSaveFunc func(buf []byte) (err error, ok bool)

PixbufSaveFunc: save functions used by gdkpixbuf.Pixbuf.SaveToCallback().

This function is called once for each block of bytes that is "written" by gdk_pixbuf_save_to_callback().

If successful it should return TRUE; if an error occurs it should set error and return FALSE, in which case gdk_pixbuf_save_to_callback() will fail with the same error.

type PixbufSimpleAnim 

type PixbufSimpleAnim struct {
	PixbufAnimation
	// contains filtered or unexported fields
}

PixbufSimpleAnim: opaque struct representing a simple animation.

func NewPixbufSimpleAnim 

func NewPixbufSimpleAnim(width, height int, rate float32) *PixbufSimpleAnim

NewPixbufSimpleAnim creates a new, empty animation.

The function takes the following parameters:

  • width of the animation.
  • height of the animation.
  • rate: speed of the animation, in frames per second.

The function returns the following values:

  • pixbufSimpleAnim: newly allocated PixbufSimpleAnim.

func (*PixbufSimpleAnim) AddFrame 

func (animation *PixbufSimpleAnim) AddFrame(pixbuf *Pixbuf)

AddFrame adds a new frame to animation. The pixbuf must have the dimensions specified when the animation was constructed.

The function takes the following parameters:

  • pixbuf to add.

func (*PixbufSimpleAnim) Loop 

func (animation *PixbufSimpleAnim) Loop() bool

Loop gets whether animation should loop indefinitely when it reaches the end.

The function returns the following values:

  • ok: TRUE if the animation loops forever, FALSE otherwise.

func (*PixbufSimpleAnim) SetLoop 

func (animation *PixbufSimpleAnim) SetLoop(loop bool)

SetLoop sets whether animation should loop indefinitely when it reaches the end.

The function takes the following parameters:

  • loop: whether to loop the animation.

type PixbufSimpleAnimIter 

type PixbufSimpleAnimIter struct {
	PixbufAnimationIter
	// contains filtered or unexported fields
}

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