README

Go API Reference 1.4.1 release Join us on Slack
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About

Fyne is an easy to use UI toolkit and app API written in Go. It is designed to build applications that run on desktop and mobile devices with a single codebase.

Version 1.4 is the current release - it introduced high performance collection widgets, Card, Separator and FileIcon widgets as well as a folder open dialog. It also saw a theme refresh updating the colors and button styles for a more material design look. We are now working towards 2.0 which aims to add data bindings, animations and more!

Prerequisites

To develop apps using Fyne you will need Go version 1.12 or later, a C compiler and your system's development tools. If you're not sure if that's all installed or you don't know how then check out our Getting Started document.

Using the standard go tools you can install Fyne's core library using:

$ go get fyne.io/fyne

Widget demo

To run a showcase of the features of Fyne execute the following:

$ go get fyne.io/fyne/cmd/fyne_demo/
$ fyne_demo

And you should see something like this (after you click a few buttons):

Fyne Hello Light Theme

Or if you are using the light theme:

Fyne Hello Light Theme

Getting Started

Fyne is designed to be really easy to code with. If you have followed the prerequisite steps above then all you need is a Go IDE (or a text editor).

Open a new file and you're ready to write your first app!

package main

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

func main() {
	a := app.New()
	w := a.NewWindow("Hello")

	hello := widget.NewLabel("Hello Fyne!")
	w.SetContent(widget.NewVBox(
		hello,
		widget.NewButton("Hi!", func() {
			hello.SetText("Welcome :)")
		}),
	))

	w.ShowAndRun()
}

And you can run that simply as:

go run main.go

It should look like this:

Fyne Hello Dark Theme Fyne Hello Dark Theme

Note that Windows applications load from a command prompt by default, which means if you click an icon you may see a command window. To fix this add the parameters -ldflags -H=windowsgui to your run or build commands.

Installing

Using go install will copy the executable into your go bin dir. To install the application with icons etc into your operating system's standard application location you can use the fyne utility and the "install" subcommand.

$ go get fyne.io/fyne/cmd/fyne
$ fyne install

Packaging a release

Using the fyne utility "release" subcommand you can package up your app for release to app stores and market places. Make sure you have the standard build tools installed and have followed the platform documentation for setting up accounts and signing. Then you can execute something like the following, notice the -os ios parameter allows building an iOS app from macOS computer. Other combinations work as well :)

$ fyne release -os ios -certificate "Apple Distribution" -profile "My App Distribution" -appID "com.example.myapp"

The above command will create a '.ipa' file that can then be uploaded to the iOS App Store.

Documentation

More documentation is available at the Fyne developer website or on pkg.go.dev.

Examples

You can find many example applications in the examples repository. Alternatively a list of applications using fyne can be found at our website.

Expand ▾ Collapse ▴

Documentation

Overview

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")

	hello := widget.NewLabel("Hello Fyne!")
	w.SetContent(widget.NewVBox(
		hello,
		widget.NewButton("Hi!", func() {
			hello.SetText("Welcome :)")
		}),
	))

	w.ShowAndRun()
}

Index

Constants

const SettingsScaleAuto = float32(-1.0)

SettingsScaleAuto is a specific scale value that indicates a canvas should scale according to the DPI of the window that contains it.

Deprecated: Automatic scaling is now handled in the drivers and is not a user setting.


Variables

This section is empty.

Functions

func IsHorizontal

func IsHorizontal(orient DeviceOrientation) bool

IsHorizontal is a helper utility that determines if a passed orientation is horizontal

func IsVertical

func IsVertical(orient DeviceOrientation) bool

IsVertical is a helper utility that determines if a passed orientation is vertical

func LogError

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

func Max(x, y int) int

Max returns the larger of the passed values.

func Min

func Min(x, y int) int

Min returns the smaller of the passed values.

func SetCurrentApp

func SetCurrentApp(current App)

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

Types

type App

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.
	SetIcon(Resource)

	// 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.
	Run()

	// Calling Quit on the application will cause the application to exit
	// cleanly, closing all open windows.
	// This function does no thing on a mobile device as the application lifecycle is
	// managed by the operating system.
	Quit()

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

	// UniqueID returns the application unique identifier, if set.
	// This must be set for use of the Preferences() functions... see NewWithId(string)
	UniqueID() string

	// SendNotification sends a system notification that will be displayed in the operating system's notification area.
	SendNotification(*Notification)

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

	// Preferences returns the application preferences, used for storing configuration and state
	Preferences() Preferences

	// Storage returns a storage handler specific to this application.
	Storage() Storage
}

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

func CurrentApp() App

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

type BuildType

type BuildType int

BuildType defines different modes that an application can be built using.

const (
	// BuildStandard is the normal build mode - it is not debug, test or release mode.
	BuildStandard BuildType = iota
	// BuildDebug is used when a developer would like more information and visual output for app debugging.
	BuildDebug
	// BuildRelease is a final production build, it is like BuildStandard but will use distribution certificates.
	// A release build is typically going to connect to live services and is not usually used during development.
	BuildRelease
)

type Canvas

type Canvas interface {
	Content() CanvasObject
	SetContent(CanvasObject)

	Refresh(CanvasObject)

	// Focus makes the provided item focused.
	// The item has to be added to the contents of the canvas before calling this.
	Focus(Focusable)
	Unfocus()
	Focused() Focusable

	// Size returns the current size of this canvas
	Size() Size
	// Scale returns the current scale (multiplication factor) this canvas uses to render
	// The pixel size of a CanvasObject can be found by multiplying by this value.
	Scale() float32
	// SetScale sets ths scale for this canvas only, overriding system and user settings.
	//
	// Deprecated: Settings are now calculated solely on the user configuration and system setup.
	SetScale(float32)

	// Overlay returns the current overlay.
	//
	// Deprecated: Overlays are stacked now.
	// This method returns the top of the overlay stack.
	// Use Overlays() instead.
	Overlay() CanvasObject
	// Overlays returns the overlay stack.
	Overlays() OverlayStack
	// SetOverlay sets the overlay for the canvas.
	//
	// Deprecated: Overlays are stacked now.
	// This method replaces the whole stack by the given overlay.
	// Use Overlays() instead.
	SetOverlay(CanvasObject)

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

	Capture() image.Image

	// PixelCoordinateForPosition returns the x and y pixel coordinate for a given position on this canvas.
	// This can be used to find absolute pixel positions or pixel offsets relative to an object top left.
	PixelCoordinateForPosition(Position) (int, int)

	// InteractiveArea returns the position and size of the central interactive area.
	// Operating system elements may overlap the portions outside this area and widgets should avoid being outside.
	InteractiveArea() (Position, Size)
}

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

type CanvasObject interface {

	// MinSize returns the minimum size this object needs to be drawn.
	MinSize() Size
	// Move moves this object to the given position relative to its parent.
	// This should only be called if your object is not in a container with a layout manager.
	Move(Position)
	// Position returns the current position of the object relative to its parent.
	Position() Position
	// Resize resizes this object to the given size.
	// This should only be called if your object is not in a container with a layout manager.
	Resize(Size)
	// Size returns the current size of this object.
	Size() Size

	// Hide hides this object.
	Hide()
	// Visible returns whether this object is visible or not.
	Visible() bool
	// Show shows this object.
	Show()

	// Refresh must be called if this object should be redrawn because its inner state changed.
	Refresh()
}

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

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

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

func NewContainer(objects ...CanvasObject) *Container

NewContainer returns a new Container instance holding the specified CanvasObjects.

Deprecated: Use NewContainerWithoutLayout to create a container that uses manual layout.

func NewContainerWithLayout

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 NewContainerWithoutLayout

func NewContainerWithoutLayout(objects ...CanvasObject) *Container

NewContainerWithoutLayout returns a new Container instance holding the specified CanvasObjects that are manually arranged.

func (*Container) Add

func (c *Container) Add(add CanvasObject)

Add appends the specified object to the items this container manages.

func (*Container) AddObject

func (c *Container) AddObject(o CanvasObject)

AddObject adds another CanvasObject to the set this Container holds.

Deprecated: Use replacement Add() function

func (*Container) Hide

func (c *Container) Hide()

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

func (*Container) MinSize

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

func (c *Container) Move(pos Position)

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

func (*Container) Position

func (c *Container) Position() Position

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

func (*Container) Refresh

func (c *Container) Refresh()

Refresh causes this object to be redrawn in it's current state

func (*Container) Remove

func (c *Container) Remove(rem CanvasObject)

Remove updates the contents of this container to no longer include the specified object.

func (*Container) Resize

func (c *Container) Resize(size Size)

Resize sets a new size for the Container.

func (*Container) Show

func (c *Container) Show()

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

func (*Container) Size

func (c *Container) Size() Size

Size returns the current size of this container.

func (*Container) Visible

func (c *Container) Visible() bool

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

type Device

type Device interface {
	Orientation() DeviceOrientation
	IsMobile() bool
	HasKeyboard() bool
	SystemScaleForWindow(Window) float32

	// Deprecated: Use SystemScaleForWindow instead - system scale can vary depending on window placement
	SystemScale() float32
}

Device provides information about the devices the code is running on

func CurrentDevice

func CurrentDevice() Device

CurrentDevice returns the device information for the current hardware (via the driver)

type DeviceOrientation

type DeviceOrientation int

DeviceOrientation represents the different ways that a mobile device can be held

const (
	// OrientationVertical is the default vertical orientation
	OrientationVertical DeviceOrientation = iota
	// OrientationVerticalUpsideDown is the portrait orientation held upside down
	OrientationVerticalUpsideDown
	// OrientationHorizontalLeft is used to indicate a landscape orientation with the top to the left
	OrientationHorizontalLeft
	// OrientationHorizontalRight is used to indicate a landscape orientation with the top to the right
	OrientationHorizontalRight
)

type Disableable

type Disableable interface {
	Enable()
	Disable()
	Disabled() bool
}

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

type DoubleTappable

type DoubleTappable interface {
	DoubleTapped(*PointEvent)
}

DoubleTappable describes any CanvasObject that can also be double tapped.

type DragEvent

type DragEvent struct {
	PointEvent
	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

type Draggable interface {
	Dragged(*DragEvent)
	DragEnd()
}

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

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

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

	// FileReaderForURI opens a file reader for the given resource indicator.
	// This may refer to a filesystem (typical on desktop) or data from another application.
	FileReaderForURI(URI) (URIReadCloser, error)

	// FileWriterForURI opens a file writer for the given resource indicator.
	// This should refer to a filesystem resource as external data will not be writable.
	FileWriterForURI(URI) (URIWriteCloser, error)

	// ListerForURI converts a URI to a listable URI, if it is possible to do so.
	ListerForURI(URI) (ListableURI, error)

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

	// Device returns the device that the application is currently running on.
	Device() Device
	// Run starts the main event loop of the driver.
	Run()
	// Quit closes the driver and open windows, then exit the application.
	Quit()
}

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

type Focusable

type Focusable interface {
	// FocusGained is a hook called by the focus handling logic after this object gained the focus.
	FocusGained()
	// FocusLost is a hook called by the focus handling logic after this object lost the focus.
	FocusLost()
	// Deprecated: this is an internal detail, canvas tracks current focused object
	Focused() bool

	// TypedRune is a hook called by the input handling logic on text input events if this object is focused.
	TypedRune(rune)
	// TypedKey is a hook called by the input handling logic on key events if this object is focused.
	TypedKey(*KeyEvent)
}

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.

Note: You must not change canvas state (including overlays or focus) in FocusGained or FocusLost or you would end up with a dead-lock.

type KeyEvent

type KeyEvent struct {
	Name KeyName
}

KeyEvent describes a keyboard input event.

type KeyName

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"

	// KeySpace is the space key
	KeySpace KeyName = "Space"
	// KeyApostrophe is the key "'"
	KeyApostrophe KeyName = "'"
	// KeyComma is the key ","
	KeyComma KeyName = ","
	// KeyMinus is the key "-"
	KeyMinus KeyName = "-"
	// KeyPeriod is the key "." (full stop)
	KeyPeriod KeyName = "."
	// KeySlash is the key "/"
	KeySlash KeyName = "/"
	// KeyBackslash is the key "\"
	KeyBackslash KeyName = "\\"
	// KeyLeftBracket is the key "["
	KeyLeftBracket KeyName = "["
	// KeyRightBracket is the key "]"
	KeyRightBracket KeyName = "]"
	// KeySemicolon is the key ";"
	KeySemicolon KeyName = ";"
	// KeyEqual is the key "="
	KeyEqual KeyName = "="
	// KeyAsterisk is the keypad key "*"
	KeyAsterisk KeyName = "*"
	// KeyPlus is the keypad key "+"
	KeyPlus KeyName = "+"
	// KeyBackTick is the key "`" on a US keyboard
	KeyBackTick KeyName = "`"
)

type Layout

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 ListableURI

type ListableURI interface {
	URI

	// List returns a list of child URIs of this URI.
	List() ([]URI, error)
}

ListableURI represents a URI that can have child items, most commonly a directory on disk in the native filesystem.

type MainMenu struct {
	Items []*Menu
}

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

func NewMainMenu

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

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 {
	ChildMenu   *Menu
	IsSeparator bool
	Label       string
	Action      func()
}

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

func NewMenuItem

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

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

func NewMenuItemSeparator

func NewMenuItemSeparator() *MenuItem

NewMenuItemSeparator creates a menu item that is to be used as a separator.

type Notification

type Notification struct {
	Title, Content string
}

Notification represents a user notification that can be sent to the operating system.

func NewNotification

func NewNotification(title, content string) *Notification

NewNotification creates a notification that can be passed to App.SendNotification.

type OverlayStack

type OverlayStack interface {
	// Add adds an overlay on the top of the overlay stack.
	Add(overlay CanvasObject)
	// List returns the overlays currently on the overlay stack.
	List() []CanvasObject
	// Remove removes the given object and all objects above it from the overlay stack.
	Remove(overlay CanvasObject)
	// Top returns the top-most object of the overlay stack.
	Top() CanvasObject
}

OverlayStack is a stack of CanvasObjects intended to be used as overlays of a Canvas.

type PointEvent

type PointEvent struct {
	AbsolutePosition Position // The absolute position of the event
	Position         Position // The relative 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

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

func NewPos(x int, y int) Position

NewPos returns a newly allocated Position representing the specified coordinates.

func (Position) Add

func (p 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) IsZero

func (p Position) IsZero() bool

IsZero returns whether the Position is at the zero-point.

func (Position) Subtract

func (p 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 Preferences

type Preferences interface {
	// Bool looks up a boolean value for the key
	Bool(key string) bool
	// BoolWithFallback looks up a boolean value and returns the given fallback if not found
	BoolWithFallback(key string, fallback bool) bool
	// SetBool saves a boolean value for the given key
	SetBool(key string, value bool)

	// Float looks up a float64 value for the key
	Float(key string) float64
	// FloatWithFallback looks up a float64 value and returns the given fallback if not found
	FloatWithFallback(key string, fallback float64) float64
	// SetFloat saves a float64 value for the given key
	SetFloat(key string, value float64)

	// Int looks up an integer value for the key
	Int(key string) int
	// IntWithFallback looks up an integer value and returns the given fallback if not found
	IntWithFallback(key string, fallback int) int
	// SetInt saves an integer value for the given key
	SetInt(key string, value int)

	// String looks up a string value for the key
	String(key string) string
	// StringWithFallback looks up a string value and returns the given fallback if not found
	StringWithFallback(key, fallback string) string
	// SetString saves a string value for the given key
	SetString(key string, value string)

	// RemoveValue removes a value for the given key (not currently supported on iOS)
	RemoveValue(key string)
}

Preferences describes the ways that an app can save and load user preferences

type Resource

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.

func LoadResourceFromPath

func LoadResourceFromPath(path string) (Resource, error)

LoadResourceFromPath creates a new StaticResource in memory using the contents of the specified file.

func LoadResourceFromURLString

func LoadResourceFromURLString(urlStr string) (Resource, error)

LoadResourceFromURLString creates a new StaticResource in memory using the body of the specified URL.

type ScrollEvent

type ScrollEvent struct {
	PointEvent
	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

type Scrollable interface {
	Scrolled(*ScrollEvent)
}

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

type SecondaryTappable

type SecondaryTappable interface {
	TappedSecondary(*PointEvent)
}

SecondaryTappable describes a CanvasObject that can be right-clicked or long-tapped.

type Settings

type Settings interface {
	Theme() Theme
	SetTheme(Theme)
	Scale() float32
	PrimaryColor() string

	AddChangeListener(chan Settings)
	BuildType() BuildType
}

Settings describes the application configuration available.

type Shortcut

type Shortcut interface {
	ShortcutName() string
}

Shortcut is the interface used to describe a shortcut action

type ShortcutCopy

type ShortcutCopy struct {
	Clipboard Clipboard
}

ShortcutCopy describes a shortcut copy action.

func (*ShortcutCopy) ShortcutName

func (se *ShortcutCopy) ShortcutName() string

ShortcutName returns the shortcut name

type ShortcutCut

type ShortcutCut struct {
	Clipboard Clipboard
}

ShortcutCut describes a shortcut cut action.

func (*ShortcutCut) ShortcutName

func (se *ShortcutCut) ShortcutName() string

ShortcutName returns the shortcut name

type ShortcutHandler

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

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

func (*ShortcutHandler) AddShortcut

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) RemoveShortcut

func (sh *ShortcutHandler) RemoveShortcut(shortcut Shortcut)

RemoveShortcut removes a registered shortcut

func (*ShortcutHandler) TypedShortcut

func (sh *ShortcutHandler) TypedShortcut(shortcut Shortcut)

TypedShortcut handle the registered shortcut

type ShortcutPaste

type ShortcutPaste struct {
	Clipboard Clipboard
}

ShortcutPaste describes a shortcut paste action.

func (*ShortcutPaste) ShortcutName

func (se *ShortcutPaste) ShortcutName() string

ShortcutName returns the shortcut name

type ShortcutSelectAll

type ShortcutSelectAll struct{}

ShortcutSelectAll describes a shortcut selectAll action.

func (*ShortcutSelectAll) ShortcutName

func (se *ShortcutSelectAll) ShortcutName() string

ShortcutName returns the shortcut name

type Shortcutable

type Shortcutable interface {
	TypedShortcut(Shortcut)
}

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

type Size

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 MeasureText

func MeasureText(text string, size int, style TextStyle) Size

MeasureText uses the current driver to calculate the size of text when rendered.

func NewSize

func NewSize(w int, h int) Size

NewSize returns a newly allocated Size of the specified dimensions.

func (Size) Add

func (s 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) IsZero

func (s Size) IsZero() bool

IsZero returns whether the Size has zero width and zero height.

func (Size) Max

func (s Size) Max(s2 Size) Size

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

func (Size) Min

func (s Size) Min(s2 Size) Size

Min returns a new Size that is the minimum of the current Size and s2.

func (Size) Subtract

func (s 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

func (s Size) Union(s2 Size) Size

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

Deprecated: use Max() instead

type StaticResource

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

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

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

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

func (r *StaticResource) Name() string

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

type Storage

type Storage interface {
	RootURI() URI
}

Storage is used to manage file storage inside an application sandbox

type StringValidator

type StringValidator func(string) error

StringValidator is a function signature for validating string inputs.

type Tappable

type Tappable interface {
	Tapped(*PointEvent)
}

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

type TextAlign

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.
	TextAlignCenter
	// TextAlignTrailing will align the text right for a left-to-right language.
	TextAlignTrailing
)

type TextStyle

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 TextWrap

type TextWrap int

TextWrap represents how text longer than the widget's width will be wrapped.

const (
	// TextWrapOff extends the widget's width to fit the text, no wrapping is applied.
	TextWrapOff TextWrap = iota
	// TextTruncate trims the text to the widget's width, no wrapping is applied.
	TextTruncate
	// TextWrapBreak trims the line of characters to the widget's width adding the excess as new line.
	TextWrapBreak
	// TextWrapWord trims the line of words to the widget's width adding the excess as new line.
	TextWrapWord
)

type Theme

type Theme interface {
	BackgroundColor() color.Color
	ButtonColor() color.Color
	DisabledButtonColor() color.Color
	// Deprecated: Hyperlinks now use the primary color for consistency.
	HyperlinkColor() color.Color
	TextColor() color.Color
	DisabledTextColor() color.Color
	// Deprecated: Icons now use the text colour for consistency.
	IconColor() color.Color
	// Deprecated: Disabled icons match disabled text color for consistency.
	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 URI

type URI interface {
	fmt.Stringer
	Extension() string
	Name() string
	MimeType() string
	Scheme() string
}

URI represents the identifier of a resource on a target system. This resource may be a file or another data source such as an app or file sharing system.

type URIReadCloser

type URIReadCloser interface {
	io.ReadCloser
	// Deprecated, use URI().Name() instead
	Name() string
	URI() URI
}

URIReadCloser represents a cross platform data stream from a file or provider of data. It may refer to an item on a filesystem or data in another application that we have access to.

type URIWriteCloser

type URIWriteCloser interface {
	io.WriteCloser
	// Deprecated, use URI().Name() instead
	Name() string
	URI() URI
}

URIWriteCloser represents a cross platform data writer for a file resource. This will normally refer to a local file resource.

type Validatable

type Validatable interface {
	Validate() error

	// SetOnValidationChanged is used to set the callback that will be triggered when the validation state changes.
	// The function might be overwritten by a parent that cares about child validation (e.g. widget.Form).
	SetOnValidationChanged(func(error))
}

Validatable is an interface for specifying if a widget is validatable.

type Widget

type Widget interface {
	CanvasObject

	// CreateRenderer returns a new WidgetRenderer for this widget.
	// This should not be called by regular code, it is used internally to render a widget.
	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

type WidgetRenderer interface {
	// BackgroundColor returns the color that should be used to draw the background of this renderer’s widget.
	//
	// Deprecated: Widgets will no longer have a background to support hover and selection indication in collection widgets.
	// If a widget requires a background color or image, this can be achieved by using a canvas.Rect or canvas.Image
	// as the first child of a MaxLayout, followed by the rest of the widget components.
	BackgroundColor() color.Color
	// Destroy is for internal use.
	Destroy()
	// Layout is a hook that is called if the widget needs to be laid out.
	// This should never call Refresh.
	Layout(Size)
	// MinSize returns the minimum size of the widget that is rendered by this renderer.
	MinSize() Size
	// Objects returns all objects that should be drawn.
	Objects() []CanvasObject
	// Refresh is a hook that is called if the widget has updated and needs to be redrawn.
	// This might trigger a Layout.
	Refresh()
}

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

type Window

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.
	SetTitle(string)

	// 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.
	SetFullScreen(bool)

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

	// 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.
	RequestFocus()

	// 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.
	SetFixedSize(bool)

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

	// 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.
	SetPadded(bool)

	// 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.
	SetIcon(Resource)

	// SetMaster indicates that closing this window should exit the app
	SetMaster()

	// 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.
	SetMainMenu(*MainMenu)

	// SetOnClosed sets a function that runs when the window is closed.
	SetOnClosed(func())

	// SetCloseIntercept sets a function that runs instead of closing if defined.
	// Close() should be called explicitly in the interceptor to close the window.
	SetCloseIntercept(func())

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

	// 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.
	ShowAndRun()

	// Content returns the content of this window.
	Content() CanvasObject
	// SetContent sets the content of this window.
	SetContent(CanvasObject)
	// 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.

Directories

Path Synopsis
app Package app provides app implementations for working with Fyne graphical interfaces.
canvas Package canvas contains all of the primitive CanvasObjects that make up a Fyne GUI The types implemented in this package are used as building blocks in order to build higher order functionality.
cmd/fyne Run a command line helper for various Fyne tools.
cmd/fyne/commands Package commands provides functionality for managing fyne packages and the build process
cmd/fyne/internal/mobile Package mobile is a partial clone of the golang.org/x/mobile/cmd/gomobile package.
cmd/fyne/internal/mobile/binres Package binres implements encoding and decoding of android binary resources.
cmd/fyne/internal/templates
cmd/fyne/internal/util
cmd/fyne_demo Package main provides various examples of Fyne API capabilities.
cmd/fyne_demo/data
cmd/fyne_demo/tutorials
cmd/fyne_settings
cmd/fyne_settings/data
cmd/fyne_settings/settings
cmd/hello Package main loads a very basic Hello World graphical application.
container Package container provides container widgets that are used to lay out and organise applications
data/validation Package validation provides validation for data inside widgets
dialog Package dialog defines standard dialog windows for application GUIs.
driver/desktop Package desktop provides desktop specific driver functionality.
driver/mobile Package mobile provides mobile specific driver functionality.
internal
internal/app
internal/cache
internal/driver
internal/driver/glfw Package glfw provides a full Fyne desktop driver that uses the system OpenGL libraries.
internal/driver/gomobile
internal/painter
internal/painter/gl Package gl provides a full Fyne render implementation using system OpenGL libraries.
internal/painter/software
internal/test
internal/widget
layout Package layout defines the various layouts available to Fyne apps
storage Package storage provides storage access and management functionality.
test Package test provides utility drivers for running UI tests without rendering
theme Package theme defines how a Fyne app should look when rendered
tools/playground Package playground provides tooling for running fyne applications inside the Go playground.
widget Package widget defines the UI widgets within the Fyne toolkit