fyne: fyne.io/fyne Index | Files | Directories

package fyne

import "fyne.io/fyne"

Package fyne describes the objects and components available to any Fyne app. These can all be created, manipulated and tested without rendering (for speed). Your main package should use the app package to create an application with a default driver that will render your UI.

A simple application may look like this:

package main

import "fyne.io/fyne/app"
import "fyne.io/fyne/widget"

func main() {
	a := app.New()

	w := a.NewWindow("Hello")
		widget.NewLabel("Hello Fyne!"),
		widget.NewButton("Quit", func() {



Package Files

app.go canvas.go canvasobject.go clipboard.go container.go driver.go event.go fyne.go geometry.go key.go layout.go log.go math.go menu.go resource.go serialise.go settings.go shortcut.go text.go theme.go widget.go window.go

func LogError Uses

func LogError(reason string, err error)

LogError reports an error to the command line with the specified err cause, if not nil. The function also reports basic information about the code location.

func Max Uses

func Max(x, y int) int

Max returns the larger of the passed values.

func Min Uses

func Min(x, y int) int

Min returns the smaller of the passed values.

func SetCurrentApp Uses

func SetCurrentApp(current App)

SetCurrentApp is an internal function to set the app instance currently running.

type App Uses

type App interface {
    // Create a new window for the application.
    // The first window to open is considered the "master" and when closed
    // the application will exit.
    NewWindow(title string) Window

    // Open a URL in the default browser application.
    OpenURL(url *url.URL) error

    // Icon returns the application icon, this is used in various ways
    // depending on operating system.
    // This is also the default icon for new windows.
    Icon() Resource

    // SetIcon sets the icon resource used for this application instance.

    // Run the application - this starts the event loop and waits until Quit()
    // is called or the last window closes.
    // This should be called near the end of a main() function as it will block.

    // Calling Quit on the application will cause the application to exit
    // cleanly, closing all open windows.

    // Driver returns the driver that is rendering this application.
    // Typically not needed for day to day work, mostly internal functionality.
    Driver() Driver

    // Settings return the application settings, determining theme and so on.
    Settings() Settings

An App is the definition of a graphical application. Apps can have multiple windows, it will exit when the first window to be shown is closed. You can also cause the app to exit by calling Quit(). To start an application you need to call Run() somewhere in your main() function. Alternatively use the window.ShowAndRun() function for your main window.

func CurrentApp Uses

func CurrentApp() App

CurrentApp returns the current application, for which there is only 1 per process.

type Canvas Uses

type Canvas interface {
    Content() CanvasObject
    Focused() Focusable

    Size() Size
    Scale() float32

    Overlay() CanvasObject

    OnTypedRune() func(rune)
    OnTypedKey() func(*KeyEvent)
    AddShortcut(shortcut Shortcut, handler func(shortcut Shortcut))

    Capture() image.Image

Canvas defines a graphical canvas to which a CanvasObject or Container can be added. Each canvas has a scale which is automatically applied during the render process.

type CanvasObject Uses

type CanvasObject interface {
    // geometry
    Size() Size
    Position() Position
    MinSize() Size

    // visibility
    Visible() bool

CanvasObject describes any graphical object that can be added to a canvas. Objects have a size and position that can be controlled through this API. MinSize is used to determine the minimum size which this object should be displayed. An object will be visible by default but can be hidden with Hide() and re-shown with Show().

Note: If this object is controlled as part of a Layout you should not call Resize(Size) or Move(Position).

type Clipboard Uses

type Clipboard interface {
    // Content returns the clipboard content
    Content() string
    // SetContent sets the clipboard content
    SetContent(content string)

Clipboard represents the system clipboard interface

type Container Uses

type Container struct {
    Hidden bool // Is this Container hidden

    Layout  Layout         // The Layout algorithm for arranging child CanvasObjects
    Objects []CanvasObject // The set of CanvasObjects this container holds
    // contains filtered or unexported fields

Container is a CanvasObject that contains a collection of child objects. The layout of the children is set by the specified Layout.

func NewContainer Uses

func NewContainer(objects ...CanvasObject) *Container

NewContainer returns a new Container instance holding the specified CanvasObjects.

func NewContainerWithLayout Uses

func NewContainerWithLayout(layout Layout, objects ...CanvasObject) *Container

NewContainerWithLayout returns a new Container instance holding the specified CanvasObjects which will be laid out according to the specified Layout.

func (*Container) AddObject Uses

func (c *Container) AddObject(o CanvasObject)

AddObject adds another CanvasObject to the set this Container holds.

func (*Container) Hide Uses

func (c *Container) Hide()

Hide sets this container, and all its children, to be not visible.

func (*Container) MinSize Uses

func (c *Container) MinSize() Size

MinSize calculates the minimum size of a Container. This is delegated to the Layout, if specified, otherwise it will mimic MaxLayout.

func (*Container) Move Uses

func (c *Container) Move(pos Position)

Move the container (and all its children) to a new position, relative to its parent.

func (*Container) Position Uses

func (c *Container) Position() Position

Position gets the current position of this Container, relative to its parent.

func (*Container) Resize Uses

func (c *Container) Resize(size Size)

Resize sets a new size for the Container.

func (*Container) Show Uses

func (c *Container) Show()

Show sets this container, and all its children, to be visible.

func (*Container) Size Uses

func (c *Container) Size() Size

Size returns the current size of this container.

func (*Container) Visible Uses

func (c *Container) Visible() bool

Visible returns true if the container is currently visible, false otherwise.

type Disableable Uses

type Disableable interface {
    Disabled() bool

Disableable describes any CanvasObject that can be disabled. This is primarily used with objects that also implement the Tappable interface.

type DoubleTappable Uses

type DoubleTappable interface {

DoubleTappable describes any CanvasObject that can also be double tapped.

type DragEvent Uses

type DragEvent struct {
    DraggedX, DraggedY int

DragEvent defines the parameters of a pointer or other drag event. The DraggedX and DraggedY fields show how far the item was dragged since the last event.

type Draggable Uses

type Draggable interface {

Draggable indicates that a CanvasObject can be dragged. This is used for any item that the user has indicated should be moved across the screen.

type Driver Uses

type Driver interface {
    // Create a new UI Window.
    CreateWindow(string) Window
    // Get a slice containing all app windows.
    AllWindows() []Window

    // Return the size required to render the given string of specified
    // font size and style.
    RenderedTextSize(string, int, TextStyle) Size

    // Get the canvas that is associated with a given CanvasObject.
    CanvasForObject(CanvasObject) Canvas
    // Get the position of a given CanvasObject relative to the top/left of a canvas.
    AbsolutePositionForObject(CanvasObject) Position

    // Start the main event loop of the driver.
    // Close the driver and open windows then exit the application.

Driver defines an abstract concept of a Fyne render driver. Any implementation must provide at least these methods.

type Focusable Uses

type Focusable interface {
    Focused() bool


Focusable describes any CanvasObject that can respond to being focused. It will receive the FocusGained and FocusLost events appropriately. When focused it will also have TypedRune called as text is input and TypedKey called when other keys are pressed.

type KeyEvent Uses

type KeyEvent struct {
    Name KeyName

KeyEvent describes a keyboard input event.

type KeyName Uses

type KeyName string

KeyName represents the name of a key that has been pressed

const (
    // KeyEscape is the "esc" key
    KeyEscape KeyName = "Escape"
    // KeyReturn is the carriage return (main keyboard)
    KeyReturn KeyName = "Return"
    // KeyTab is the tab advance key
    KeyTab KeyName = "Tab"
    // KeyBackspace is the delete-before-cursor key
    KeyBackspace KeyName = "BackSpace"
    // KeyInsert is the insert mode key
    KeyInsert KeyName = "Insert"
    // KeyDelete is the delete-after-cursor key
    KeyDelete KeyName = "Delete"
    // KeyRight is the right arrow key
    KeyRight KeyName = "Right"
    // KeyLeft is the left arrow key
    KeyLeft KeyName = "Left"
    // KeyDown is the down arrow key
    KeyDown KeyName = "Down"
    // KeyUp is the up arrow key
    KeyUp KeyName = "Up"
    // KeyPageUp is the page up num-pad key
    KeyPageUp KeyName = "Prior"
    // KeyPageDown is the page down num-pad key
    KeyPageDown KeyName = "Next"
    // KeyHome is the line-home key
    KeyHome KeyName = "Home"
    // KeyEnd is the line-end key
    KeyEnd KeyName = "End"

    // KeyF1 is the first function key
    KeyF1 KeyName = "F1"
    // KeyF2 is the second function key
    KeyF2 KeyName = "F2"
    // KeyF3 is the third function key
    KeyF3 KeyName = "F3"
    // KeyF4 is the fourth function key
    KeyF4 KeyName = "F4"
    // KeyF5 is the fifth function key
    KeyF5 KeyName = "F5"
    // KeyF6 is the sixth function key
    KeyF6 KeyName = "F6"
    // KeyF7 is the seventh function key
    KeyF7 KeyName = "F7"
    // KeyF8 is the eighth function key
    KeyF8 KeyName = "F8"
    // KeyF9 is the ninth function key
    KeyF9 KeyName = "F9"
    // KeyF10 is the tenth function key
    KeyF10 KeyName = "F10"
    // KeyF11 is the eleventh function key
    KeyF11 KeyName = "F11"
    // KeyF12 is the twelfth function key
    KeyF12 KeyName = "F12"

    // KeyEnter is the enter/ return key (keypad)
    KeyEnter KeyName = "KP_Enter"

    // Key0 represents the key 0
    Key0 KeyName = "0"
    // Key1 represents the key 1
    Key1 KeyName = "1"
    // Key2 represents the key 2
    Key2 KeyName = "2"
    // Key3 represents the key 3
    Key3 KeyName = "3"
    // Key4 represents the key 4
    Key4 KeyName = "4"
    // Key5 represents the key 5
    Key5 KeyName = "5"
    // Key6 represents the key 6
    Key6 KeyName = "6"
    // Key7 represents the key 7
    Key7 KeyName = "7"
    // Key8 represents the key 8
    Key8 KeyName = "8"
    // Key9 represents the key 9
    Key9 KeyName = "9"
    // KeyA represents the key A
    KeyA KeyName = "A"
    // KeyB represents the key B
    KeyB KeyName = "B"
    // KeyC represents the key C
    KeyC KeyName = "C"
    // KeyD represents the key D
    KeyD KeyName = "D"
    // KeyE represents the key E
    KeyE KeyName = "E"
    // KeyF represents the key F
    KeyF KeyName = "F"
    // KeyG represents the key G
    KeyG KeyName = "G"
    // KeyH represents the key H
    KeyH KeyName = "H"
    // KeyI represents the key I
    KeyI KeyName = "I"
    // KeyJ represents the key J
    KeyJ KeyName = "J"
    // KeyK represents the key K
    KeyK KeyName = "K"
    // KeyL represents the key L
    KeyL KeyName = "L"
    // KeyM represents the key M
    KeyM KeyName = "M"
    // KeyN represents the key N
    KeyN KeyName = "N"
    // KeyO represents the key O
    KeyO KeyName = "O"
    // KeyP represents the key P
    KeyP KeyName = "P"
    // KeyQ represents the key Q
    KeyQ KeyName = "Q"
    // KeyR represents the key R
    KeyR KeyName = "R"
    // KeyS represents the key S
    KeyS KeyName = "S"
    // KeyT represents the key T
    KeyT KeyName = "T"
    // KeyU represents the key U
    KeyU KeyName = "U"
    // KeyV represents the key V
    KeyV KeyName = "V"
    // KeyW represents the key W
    KeyW KeyName = "W"
    // KeyX represents the key X
    KeyX KeyName = "X"
    // KeyY represents the key Y
    KeyY KeyName = "Y"
    // KeyZ represents the key Z
    KeyZ KeyName = "Z"

type Layout Uses

type Layout interface {
    // Layout will manipulate the listed CanvasObjects Size and Position
    // to fit within the specified size.
    Layout([]CanvasObject, Size)
    // MinSize calculates the smallest size that will fit the listed
    // CanvasObjects using this Layout algorithm.
    MinSize(objects []CanvasObject) Size

Layout defines how CanvasObjects may be laid out in a specified Size.

type MainMenu struct {
    Items []*Menu

MainMenu defines the data required to show a menu bar (desktop) or other appropriate top level menu.

func NewMainMenu Uses

func NewMainMenu(items ...*Menu) *MainMenu

NewMainMenu creates a top level menu structure used by fyne.Window for displaying a menubar (or appropriate equivalent).

type Menu struct {
    Label string
    Items []*MenuItem

Menu stores the information required for a standard menu. A menu can pop down from a MainMenu or could be a pop out menu.

func NewMenu Uses

func NewMenu(label string, items ...*MenuItem) *Menu

NewMenu creates a new menu given the specified label (to show in a MainMenu) and list of items to display.

type MenuItem struct {
    Label  string
    Action func()

MenuItem is a sligne item within any menu, it contains a dispay Label and Action function that is called when tapped.

func NewMenuItem Uses

func NewMenuItem(label string, action func()) *MenuItem

NewMenuItem creates a new menu item from the passed label and action parameters.

type PointEvent Uses

type PointEvent struct {
    Position Position // The position of the event

PointEvent describes a pointer input event. The position is relative to the top-left of the CanvasObject this is triggered on.

type Position Uses

type Position struct {
    X   int // The position from the parent's left edge
    Y   int // The position from the parent's top edge

Position describes a generic X, Y coordinate relative to a parent Canvas or CanvasObject.

func NewPos Uses

func NewPos(x int, y int) Position

NewPos returns a newly allocated Position representing the specified coordinates.

func (Position) Add Uses

func (p1 Position) Add(p2 Position) Position

Add returns a new Position that is the result of offsetting the current position by p2 X and Y.

func (Position) Subtract Uses

func (p1 Position) Subtract(p2 Position) Position

Subtract returns a new Position that is the result of offsetting the current position by p2 -X and -Y.

type Resource Uses

type Resource interface {
    Name() string
    Content() []byte

Resource represents a single binary resource, such as an image or font. A resource has an identifying name and byte array content. The serialised path of a resource can be obtained which may result in a blocking filesystem write operation.

type ScrollEvent Uses

type ScrollEvent struct {
    DeltaX, DeltaY int

ScrollEvent defines the parameters of a pointer or other scroll event. The DeltaX and DeltaY represent how large the scroll was in two dimensions.

type Scrollable Uses

type Scrollable interface {

Scrollable describes any CanvasObject that can also be scrolled. This is mostly used to implement the widget.ScrollContainer.

type Settings Uses

type Settings interface {
    Theme() Theme

    AddChangeListener(chan Settings)

Settings describes the application configuration available.

type Shortcut Uses

type Shortcut interface {
    ShortcutName() string

Shortcut is the interface used to describe a shortcut action

type ShortcutCopy Uses

type ShortcutCopy struct {
    Clipboard Clipboard

ShortcutCopy describes a shortcut copy action.

func (*ShortcutCopy) ShortcutName Uses

func (se *ShortcutCopy) ShortcutName() string

ShortcutName returns the shortcut name

type ShortcutCut Uses

type ShortcutCut struct {
    Clipboard Clipboard

ShortcutCut describes a shortcut cut action.

func (*ShortcutCut) ShortcutName Uses

func (se *ShortcutCut) ShortcutName() string

ShortcutName returns the shortcut name

type ShortcutHandler Uses

type ShortcutHandler struct {
    // contains filtered or unexported fields

ShortcutHandler is a default implementation of the shortcut handler for the canvasObject

func (*ShortcutHandler) AddShortcut Uses

func (sh *ShortcutHandler) AddShortcut(shortcut Shortcut, handler func(shortcut Shortcut))

AddShortcut register an handler to be executed when the shortcut action is triggered

func (*ShortcutHandler) TypedShortcut Uses

func (sh *ShortcutHandler) TypedShortcut(shortcut Shortcut) bool

TypedShortcut handle the registered shortcut

type ShortcutPaste Uses

type ShortcutPaste struct {
    Clipboard Clipboard

ShortcutPaste describes a shortcut paste action.

func (*ShortcutPaste) ShortcutName Uses

func (se *ShortcutPaste) ShortcutName() string

ShortcutName returns the shortcut name

type Shortcutable Uses

type Shortcutable interface {
    TypedShortcut(shortcut Shortcut) bool

Shortcutable describes any CanvasObject that can respond to shortcut commands (quit, cut, copy, and paste).

type Size Uses

type Size struct {
    Width  int // The number of units along the X axis.
    Height int // The number of units along the Y axis.

Size describes something with width and height.

func NewSize Uses

func NewSize(w int, h int) Size

NewSize returns a newly allocated Size of the specified dimensions.

func (Size) Add Uses

func (s1 Size) Add(s2 Size) Size

Add returns a new Size that is the result of increasing the current size by s2 Width and Height.

func (Size) Subtract Uses

func (s1 Size) Subtract(s2 Size) Size

Subtract returns a new Size that is the result of decreasing the current size by s2 Width and Height.

func (Size) Union Uses

func (s1 Size) Union(s2 Size) Size

Union returns a new Size that is the maximum of the current Size and s2.

type StaticResource Uses

type StaticResource struct {
    StaticName    string
    StaticContent []byte

StaticResource is a bundled resource compiled into the application. These resources are normally generated by the fyne_bundle command included in the Fyne toolkit.

func NewStaticResource Uses

func NewStaticResource(name string, content []byte) *StaticResource

NewStaticResource returns a new static resource object with the specified name and content. Creating a new static resource in memory results in sharable binary data that may be serialised to the location returned by CachePath().

func (*StaticResource) Content Uses

func (r *StaticResource) Content() []byte

Content returns the bytes of the bundled resource, no compression is applied but any compression on the resource is retained.

func (*StaticResource) GoString Uses

func (r *StaticResource) GoString() string

GoString converts a Resource object to Go code. This is useful if serialising to a Go file for compilation into a binary.

func (*StaticResource) Name Uses

func (r *StaticResource) Name() string

Name returns the unique name of this resource, usually matching the file it was generated from.

type Tappable Uses

type Tappable interface {

Tappable describes any CanvasObject that can also be tapped. This should be implemented by buttons etc that wish to handle pointer interactions.

type TextAlign Uses

type TextAlign int

TextAlign represents the horizontal alignment of text within a widget or canvas object.

const (
    // TextAlignLeading specifies a left alignment for left-to-right languages.
    TextAlignLeading TextAlign = iota
    // TextAlignCenter places the text centrally within the available space.
    // TextAlignTrailing will align the text right for a left-to-right language.

type TextStyle Uses

type TextStyle struct {
    Bold      bool // Should text be bold
    Italic    bool // Should text be italic
    Monospace bool // Use the system monospace font instead of regular

TextStyle represents the styles that can be applied to a text canvas object or text based widget.

type Theme Uses

type Theme interface {
    BackgroundColor() color.Color
    ButtonColor() color.Color
    DisabledButtonColor() color.Color
    HyperlinkColor() color.Color
    TextColor() color.Color
    DisabledTextColor() color.Color
    IconColor() color.Color
    DisabledIconColor() color.Color
    PlaceHolderColor() color.Color
    PrimaryColor() color.Color
    HoverColor() color.Color
    FocusColor() color.Color
    ScrollBarColor() color.Color
    ShadowColor() color.Color

    TextSize() int
    TextFont() Resource
    TextBoldFont() Resource
    TextItalicFont() Resource
    TextBoldItalicFont() Resource
    TextMonospaceFont() Resource

    Padding() int
    IconInlineSize() int
    ScrollBarSize() int
    ScrollBarSmallSize() int

Theme defines the requirements of any Fyne theme.

type Themeable Uses

type Themeable interface {

Themeable indicates that the associated CanvasObject responds to theme changes. When the settings detect a theme change the object will be informed through the invocation of ApplyTheme().

type Widget Uses

type Widget interface {

    CreateRenderer() WidgetRenderer

Widget defines the standard behaviours of any widget. This extends the CanvasObject - a widget behaves in the same basic way but will encapsulate many child objects to create the rendered widget.

type WidgetRenderer Uses

type WidgetRenderer interface {
    MinSize() Size

    BackgroundColor() color.Color
    Objects() []CanvasObject

WidgetRenderer defines the behaviour of a widget's implementation. This is returned from a widget's declarative object through the Render() function and should be exactly one instance per widget in memory.

type Window Uses

type Window interface {
    // Title returns the current window title.
    // This is typically displayed in the window decorations.
    Title() string
    // SetTitle updates the current title of the window.

    // FullScreen returns whether or not this window is currently full screen.
    FullScreen() bool
    // SetFullScreen changes the requested fullScreen property
    // true for a fullScreen window and false to unset this.

    // Resize this window to the requested content size.
    // The result may not be exactly as desired due to various desktop or
    // platform constraints.

    // RequestFocus attempts to raise and focus this window.
    // This should only be called when you are sure the user would want this window
    // to steal focus from any current focused window.

    // FixedSize returns whether or not this window should disable resizing.
    FixedSize() bool
    // SetFixedSize sets a hint that states whether the window should be a fixed
    // size or allow resizing.

    // CenterOnScreen places a window at the center of the monitor
    // the Window object is currently positioned on.

    // Padded, normally true, states whether the window should have inner
    // padding so that components do not touch the window edge.
    Padded() bool
    // SetPadded allows applications to specify that a window should have
    // no inner padding. Useful for fullscreen or graphic based applications.

    // Icon returns the window icon, this is used in various ways
    // depending on operating system.
    // Most commonly this is displayed on the window border or task switcher.
    Icon() Resource

    // SetIcon sets the icon resource used for this window.
    // If none is set should return the application icon.

    // MainMenu gets the content of the window's top level menu.
    MainMenu() *MainMenu

    // SetMainMenu adds a top level menu to this window.
    // The way this is rendered will depend on the loaded driver.


    // Show the window on screen.
    // Hide the window from the user.
    // This will not destroy the window or cause the app to exit.
    // Close the window.
    // If it is the only open window, or the "master" window the app will Quit.

    // ShowAndRun is a shortcut to show the window and then run the application.
    // This should be called near the end of a main() function as it will block.

    // Content returns the content of this window.
    Content() CanvasObject
    // SetContent sets the content of this window.
    // Canvas returns the canvas context to render in the window.
    // This can be useful to set a key handler for the window, for example.
    Canvas() Canvas

    //Clipboard returns the system clipboard
    Clipboard() Clipboard

Window describes a user interface window. Depending on the platform an app may have many windows or just the one.


appPackage app provides app implementations for working with Fyne graphical interfaces.
canvasPackage canvas contains all of the primitive CanvasObjects that make up a Fyne GUI
cmd/fyneRun a command line helper for various Fyne tools.
dialogPackage dialog defines standard dialog windows for application GUIs
layoutPackage layout defines the various layouts available to Fyne apps
testPackage test provides utility drivers for running UI tests without rendering
themePackage theme defines how a Fyne app should look when rendered
widgetPackage widget defines the UI widgets within the Fyne toolkit

Package fyne imports 8 packages (graph) and is imported by 22 packages. Updated 2019-10-11. Refresh now. Tools for package owners.