contentstream

package
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 Go to latest Published: Jul 14, 2018 License: AGPL-3.0 Imports: 13 Imported by: 0

Documentation

Overview

The contentstream package provides functionality for parsing and creating content streams for PDF files.

For processing and manipulating content streams, it allows parse the content stream into a list of operands that can then be processed further for rendering or extraction of information. The ContentStreamProcessor offers a basic engine for processing the content stream and can be used to render or modify the contents.

For creating content streams, see NewContentCreator. It allows adding multiple operands and then can be converted to a string for embedding in a PDF file.

The contentstream package uses the core and model packages.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type ContentCreator 

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

func NewContentCreator 

func NewContentCreator() *ContentCreator

func (*ContentCreator) Add_B 

func (this *ContentCreator) Add_B() *ContentCreator

B: Fill and then stroke the path (nonzero winding number rule).

func (*ContentCreator) Add_BT 

func (this *ContentCreator) Add_BT() *ContentCreator

BT: Begin text.

func (*ContentCreator) Add_B_starred 

func (this *ContentCreator) Add_B_starred() *ContentCreator

B*: Fill and then stroke the path (even-odd rule).

func (*ContentCreator) Add_CS 

func (this *ContentCreator) Add_CS(name PdfObjectName) *ContentCreator

CS: Set the current colorspace for stroking operations.

func (*ContentCreator) Add_Do 

func (this *ContentCreator) Add_Do(name PdfObjectName) *ContentCreator

Display XObject - image or form.

func (*ContentCreator) Add_ET 

func (this *ContentCreator) Add_ET() *ContentCreator

ET: End text.

func (*ContentCreator) Add_G 

func (this *ContentCreator) Add_G(gray float64) *ContentCreator

G: Set the stroking colorspace to DeviceGray and sets the gray level (0-1).

func (*ContentCreator) Add_J 

func (this *ContentCreator) Add_J(lineCapStyle string) *ContentCreator

Set the line cap style.

func (*ContentCreator) Add_K 

func (this *ContentCreator) Add_K(c, m, y, k float64) *ContentCreator

K: Set the stroking colorspace to DeviceCMYK and sets the c,m,y,k color (0-1 each component).

func (*ContentCreator) Add_M 

func (this *ContentCreator) Add_M(miterlimit float64) *ContentCreator

Set the miter limit.

func (*ContentCreator) Add_Q 

func (this *ContentCreator) Add_Q() *ContentCreator

Restore the most recently stored state from the stack - pop.

func (*ContentCreator) Add_RG 

func (this *ContentCreator) Add_RG(r, g, b float64) *ContentCreator

RG: Set the stroking colorspace to DeviceRGB and sets the r,g,b colors (0-1 each).

func (*ContentCreator) Add_S 

func (this *ContentCreator) Add_S() *ContentCreator

S: stroke the path.

func (*ContentCreator) Add_SC 

func (this *ContentCreator) Add_SC(c ...float64) *ContentCreator

SC: Set color for stroking operations. Input: c1, ..., cn.

func (*ContentCreator) Add_SCN 

func (this *ContentCreator) Add_SCN(c ...float64) *ContentCreator

SCN: Same as SC but supports more colorspaces.

func (*ContentCreator) Add_SCN_pattern 

func (this *ContentCreator) Add_SCN_pattern(name PdfObjectName, c ...float64) *ContentCreator

SCN with name attribute (for pattern). Syntax: c1 ... cn name SCN.

func (*ContentCreator) Add_TD 

func (this *ContentCreator) Add_TD(tx, ty float64) *ContentCreator

TD: Move to start of next line with offset (tx, ty).

func (*ContentCreator) Add_TJ 

func (this *ContentCreator) Add_TJ(vals ...PdfObject) *ContentCreator

TJ. Show one or more text string. Array of numbers (displacement) and strings.

func (*ContentCreator) Add_TL 

func (this *ContentCreator) Add_TL(leading float64) *ContentCreator

TL: Set leading.

func (*ContentCreator) Add_Tc 

func (this *ContentCreator) Add_Tc(charSpace float64) *ContentCreator

Tc: Set character spacing.

func (*ContentCreator) Add_Td 

func (this *ContentCreator) Add_Td(tx, ty float64) *ContentCreator

Td: Move to start of next line with offset (tx, ty).

func (*ContentCreator) Add_Tf 

func (this *ContentCreator) Add_Tf(fontName PdfObjectName, fontSize float64) *ContentCreator

Tf: Set font and font size.

func (*ContentCreator) Add_Tj 

func (this *ContentCreator) Add_Tj(textstr PdfObjectString) *ContentCreator

Tj: Show a text string.

func (*ContentCreator) Add_Tm 

func (this *ContentCreator) Add_Tm(a, b, c, d, e, f float64) *ContentCreator

Tm: Set the text line matrix.

func (*ContentCreator) Add_Tr 

func (this *ContentCreator) Add_Tr(render int64) *ContentCreator

Tr: Set text rendering mode.

func (*ContentCreator) Add_Ts 

func (this *ContentCreator) Add_Ts(rise float64) *ContentCreator

Ts: Set text rise.

func (*ContentCreator) Add_Tstar 

func (this *ContentCreator) Add_Tstar() *ContentCreator

T*: Move to the start of next line.

func (*ContentCreator) Add_Tw 

func (this *ContentCreator) Add_Tw(wordSpace float64) *ContentCreator

Tw: Set word spacing.

func (*ContentCreator) Add_Tz 

func (this *ContentCreator) Add_Tz(scale float64) *ContentCreator

Tz: Set horizontal scaling.

func (*ContentCreator) Add_W 

func (this *ContentCreator) Add_W() *ContentCreator

W: Modify the current clipping path by intersecting with the current path (nonzero winding rule).

func (*ContentCreator) Add_W_starred 

func (this *ContentCreator) Add_W_starred() *ContentCreator

W*: Modify the current clipping path by intersecting with the current path (even odd rule).

func (*ContentCreator) Add_b 

func (this *ContentCreator) Add_b() *ContentCreator

b: Close, fill and then stroke the path (nonzero winding number rule).

func (*ContentCreator) Add_b_starred 

func (this *ContentCreator) Add_b_starred() *ContentCreator

b*: Close, fill and then stroke the path (even-odd winding number rule).

func (*ContentCreator) Add_c 

func (this *ContentCreator) Add_c(x1, y1, x2, y2, x3, y3 float64) *ContentCreator

c: Append a Bezier curve to the current path from the current point to (x3,y3) with (x1,x1) and (x2,y2) as control points.

func (*ContentCreator) Add_cm 

func (this *ContentCreator) Add_cm(a, b, c, d, e, f float64) *ContentCreator

Modify the current transformation matrix (ctm).

func (*ContentCreator) Add_cs 

func (this *ContentCreator) Add_cs(name PdfObjectName) *ContentCreator

cs: Same as CS but for non-stroking operations.

func (*ContentCreator) Add_d 

func (this *ContentCreator) Add_d(dashArray []int64, dashPhase int64) *ContentCreator

Set the line dash pattern.

func (*ContentCreator) Add_f 

func (this *ContentCreator) Add_f() *ContentCreator

f: Fill the path using the nonzero winding number rule to determine fill region.

func (*ContentCreator) Add_f_starred 

func (this *ContentCreator) Add_f_starred() *ContentCreator

f*: Fill the path using the even-odd rule to determine fill region.

func (*ContentCreator) Add_g 

func (this *ContentCreator) Add_g(gray float64) *ContentCreator

g: Same as G but used for nonstroking operations.

func (*ContentCreator) Add_gs 

func (this *ContentCreator) Add_gs(dictName PdfObjectName) *ContentCreator

Set the graphics state.

func (*ContentCreator) Add_h 

func (this *ContentCreator) Add_h() *ContentCreator

h: Close the current subpath by adding a line between the current position and the starting position.

func (*ContentCreator) Add_i 

func (this *ContentCreator) Add_i(flatness float64) *ContentCreator

Set the flatness tolerance.

func (*ContentCreator) Add_j 

func (this *ContentCreator) Add_j(lineJoinStyle string) *ContentCreator

Set the line join style.

func (*ContentCreator) Add_k 

func (this *ContentCreator) Add_k(c, m, y, k float64) *ContentCreator

k: Same as K but used for nonstroking operations.

func (*ContentCreator) Add_l 

func (this *ContentCreator) Add_l(x, y float64) *ContentCreator

l: Append a straight line segment from the current point to (x,y).

func (*ContentCreator) Add_m 

func (this *ContentCreator) Add_m(x, y float64) *ContentCreator

m: Move the current point to (x,y).

func (*ContentCreator) Add_n 

func (this *ContentCreator) Add_n() *ContentCreator

n: End the path without filling or stroking.

func (*ContentCreator) Add_q 

func (this *ContentCreator) Add_q() *ContentCreator

Save the current graphics state on the stack - push.

func (*ContentCreator) Add_quote 

func (this *ContentCreator) Add_quote(textstr PdfObjectString) *ContentCreator

': Move to next line and show a string.

func (*ContentCreator) Add_quotes 

func (this *ContentCreator) Add_quotes(textstr PdfObjectString, aw, ac float64) *ContentCreator

”: Move to next line and show a string, using aw and ac as word and character spacing respectively.

func (*ContentCreator) Add_re 

func (this *ContentCreator) Add_re(x, y, width, height float64) *ContentCreator

re: Append a rectangle to the current path as a complete subpath, with lower left corner (x,y).

func (*ContentCreator) Add_rg 

func (this *ContentCreator) Add_rg(r, g, b float64) *ContentCreator

rg: Same as RG but used for nonstroking operations.

func (*ContentCreator) Add_ri 

func (this *ContentCreator) Add_ri(intent PdfObjectName) *ContentCreator

Set the color rendering intent.

func (*ContentCreator) Add_s 

func (this *ContentCreator) Add_s() *ContentCreator

s: Close and stroke the path.

func (*ContentCreator) Add_scn 

func (this *ContentCreator) Add_scn(c ...float64) *ContentCreator

scn: Same as SC but for nonstroking operations.

func (*ContentCreator) Add_scn_pattern 

func (this *ContentCreator) Add_scn_pattern(name PdfObjectName, c ...float64) *ContentCreator

scn with name attribute (for pattern). Syntax: c1 ... cn name scn.

func (*ContentCreator) Add_sh 

func (this *ContentCreator) Add_sh(name PdfObjectName) *ContentCreator

func (*ContentCreator) Add_v 

func (this *ContentCreator) Add_v(x2, y2, x3, y3 float64) *ContentCreator

v: Append a Bezier curve to the current path from the current point to (x3,y3) with the current point and (x2,y2) as control points.

func (*ContentCreator) Add_w 

func (this *ContentCreator) Add_w(lineWidth float64) *ContentCreator

Set the line width.

func (*ContentCreator) Add_y 

func (this *ContentCreator) Add_y(x1, y1, x3, y3 float64) *ContentCreator

y: Append a Bezier curve to the current path from the current point to (x3,y3) with (x1, y1) and (x3,y3) as control points.

func (*ContentCreator) Bytes 

func (this *ContentCreator) Bytes() []byte

Convert a set of content stream operations to a content stream byte presentation, i.e. the kind that can be stored as a PDF stream or string format.

func (*ContentCreator) Operations 

func (this *ContentCreator) Operations() *ContentStreamOperations

Get the list of operations.

func (*ContentCreator) RotateDeg 

func (this *ContentCreator) RotateDeg(angle float64) *ContentCreator

Convenience function for generating a cm command to rotate transformation matrix.

func (*ContentCreator) Scale 

func (this *ContentCreator) Scale(sx, sy float64) *ContentCreator

Convenience function for generating a cm command to scale the transformation matrix.

func (*ContentCreator) String 

func (this *ContentCreator) String() string

Same as Bytes() except returns as a string for convenience.

func (*ContentCreator) Translate 

func (this *ContentCreator) Translate(tx, ty float64) *ContentCreator

Convenience function for generating a cm operation to translate the transformation matrix.

type ContentStreamInlineImage 

type ContentStreamInlineImage struct {
	BitsPerComponent core.PdfObject
	ColorSpace       core.PdfObject
	Decode           core.PdfObject
	DecodeParms      core.PdfObject
	Filter           core.PdfObject
	Height           core.PdfObject
	ImageMask        core.PdfObject
	Intent           core.PdfObject
	Interpolate      core.PdfObject
	Width            core.PdfObject
	// contains filtered or unexported fields
}

A representation of an inline image in a Content stream. Everything between the BI and EI operands. ContentStreamInlineImage implements the core.PdfObject interface although strictly it is not a PDF object.

func NewInlineImageFromImage 

func NewInlineImageFromImage(img model.Image, encoder core.StreamEncoder) (*ContentStreamInlineImage, error)

Make a new content stream inline image object from an image.

func (*ContentStreamInlineImage) DefaultWriteString 

func (this *ContentStreamInlineImage) DefaultWriteString() string

func (*ContentStreamInlineImage) GetColorSpace 

func (this *ContentStreamInlineImage) GetColorSpace(resources *model.PdfPageResources) (model.PdfColorspace, error)

func (*ContentStreamInlineImage) GetEncoder 

func (this *ContentStreamInlineImage) GetEncoder() (core.StreamEncoder, error)

func (*ContentStreamInlineImage) IsMask 

func (this *ContentStreamInlineImage) IsMask() (bool, error)

Is a mask ? The image mask entry in the image dictionary specifies that the image data shall be used as a stencil mask for painting in the current color. The mask data is 1bpc, grayscale.

func (*ContentStreamInlineImage) String 

func (this *ContentStreamInlineImage) String() string

func (*ContentStreamInlineImage) ToImage 

func (this *ContentStreamInlineImage) ToImage(resources *model.PdfPageResources) (*model.Image, error)

Export the inline image to Image which can be transformed or exported easily. Page resources are needed to look up colorspace information.

type ContentStreamOperation 

type ContentStreamOperation struct {
	Params  []PdfObject
	Operand string
}

type ContentStreamOperations 

type ContentStreamOperations []*ContentStreamOperation

func (*ContentStreamOperations) Bytes 

func (this *ContentStreamOperations) Bytes() []byte

Convert a set of content stream operations to a content stream byte presentation, i.e. the kind that can be stored as a PDF stream or string format.

func (*ContentStreamOperations) WrapIfNeeded 

func (this *ContentStreamOperations) WrapIfNeeded() *ContentStreamOperations

Wrap entire contents within q ... Q. If unbalanced, then adds extra Qs at the end. Only does if needed. Ensures that when adding new content, one start with all states in the default condition.

type ContentStreamParser 

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

Content stream parser.

func NewContentStreamParser 

func NewContentStreamParser(contentStr string) *ContentStreamParser

Create a new instance of the content stream parser from an input content stream string.

func (*ContentStreamParser) ExtractText deprecated 

func (this *ContentStreamParser) ExtractText() (string, error)

ExtractText parses and extracts all text data in content streams and returns as a string. Does not take into account Encoding table, the output is simply the character codes.

Deprecated: More advanced text extraction is offered in package extractor with character encoding support.

func (*ContentStreamParser) Parse 

func (this *ContentStreamParser) Parse() (*ContentStreamOperations, error)

Parses all commands in content stream, returning a list of operation data.

func (*ContentStreamParser) ParseInlineImage 

func (this *ContentStreamParser) ParseInlineImage() (*ContentStreamInlineImage, error)

Parse an inline image from a content stream, both read its properties and binary data. When called, "BI" has already been read from the stream. This function finishes reading through "EI" and then returns the ContentStreamInlineImage.

type ContentStreamProcessor 

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

ContentStreamProcessor defines a data structure and methods for processing a content stream, keeping track of the current graphics state, and allowing external handlers to define their own functions as a part of the processing, for example rendering or extracting certain information.

func NewContentStreamProcessor 

func NewContentStreamProcessor(ops []*ContentStreamOperation) *ContentStreamProcessor

func (*ContentStreamProcessor) AddHandler 

func (csp *ContentStreamProcessor) AddHandler(condition HandlerConditionEnum, operand string, handler HandlerFunc)

func (*ContentStreamProcessor) Process 

func (this *ContentStreamProcessor) Process(resources *PdfPageResources) error

Process the entire operations.

type GraphicStateStack 

type GraphicStateStack []GraphicsState

func (*GraphicStateStack) Pop 

func (gsStack *GraphicStateStack) Pop() GraphicsState

func (*GraphicStateStack) Push 

func (gsStack *GraphicStateStack) Push(gs GraphicsState)

type GraphicsState 

type GraphicsState struct {
	ColorspaceStroking    PdfColorspace
	ColorspaceNonStroking PdfColorspace
	ColorStroking         PdfColor
	ColorNonStroking      PdfColor
}

Basic graphics state implementation. Initially only implementing and tracking a portion of the information specified. Easy to add more.

type HandlerConditionEnum 

type HandlerConditionEnum int
const (
	HandlerConditionEnumOperand     HandlerConditionEnum = iota
	HandlerConditionEnumAllOperands HandlerConditionEnum = iota
)

func (HandlerConditionEnum) All 

func (this HandlerConditionEnum) All() bool

func (HandlerConditionEnum) Operand 

func (this HandlerConditionEnum) Operand() bool

type HandlerEntry 

type HandlerEntry struct {
	Condition HandlerConditionEnum
	Operand   string
	Handler   HandlerFunc
}

type HandlerFunc 

type HandlerFunc func(op *ContentStreamOperation, gs GraphicsState, resources *PdfPageResources) error

Source Files

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Directories

Path Synopsis
The draw package has handy features for defining paths which can be used to draw content on a PDF page.
 The draw package has handy features for defining paths which can be used to draw content on a PDF page.

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