gtk4

README

gtk4

Drive GTK4 from pure Go with CGO_ENABLED=0 — windows, the common controls, GObject signals and the GLib main loop — over ebitengine/purego.

It is the Linux sibling of go-macos/objc: the shared native-toolkit bridge a go-widgets host backend embeds real controls through, so a pixel-drawn app can inlay a real GtkEntry, GtkButton or secure field over its own rendering.

ok, err := gtk4.Init()
// win := gtk4.WindowNew(); win.SetTitle("…"); win.SetDefaultSize(360, 200)
// fixed := gtk4.FixedNew()          // the overlay container
// e := gtk4.EntryNew(); e.SetVisibility(false) // a password field
// b := gtk4.ButtonNewWithLabel("OK")
// b.Connect("clicked", func() { … }) // a GObject signal, as a Go closure
// fixed.Put(e, 10, 10); fixed.Put(b, 10, 44); win.SetChild(fixed); win.Present()

No cgo

libgtk-4, libgobject-2.0 and libglib-2.0 are dlopen'd by soname and every entry point is resolved with purego.RegisterLibFunc. A GObject signal reaches Go through a purego.NewCallback, retained for the process life (GTK holds the C pointer). The package links with no cgo and cross-compiles like any other Go code.

What it binds

Init · WindowNew (+ SetTitle/SetDefaultSize/SetChild/Present) · FixedNew (+ Put/Move — absolute overlay positioning) · ButtonNewWithLabel (+ SetLabel) · EntryNew (+ SetVisibility for a secure field) · CheckButtonNewWithLabel (+ Active/SetActive; grouped check buttons are GTK radios) · LabelNew · Text/SetText (GtkEditable) · SetSizeRequest · SetVisible · Unparent · Connect (signals) · MainLoop (Run/Quit) · IdleAdd (marshal onto the GTK thread).

Platform

Linux only — this is the GTK path; a go-widgets host uses AppKit/Win32 on macOS/Windows. Off Linux the package still compiles (a consumer cross-compiles without a build tag) and every constructor's Init returns ErrUnsupported, so nothing is a build-time surprise. It needs only the runtime libgtk-4 (libgtk-4-1 on Debian/Ubuntu) — no -dev package.

Testing

CI builds it on every platform and runs a live test against real GTK4 under a headless X server (Xvfb) — creating a window, entry, secure field, button and check button, round-tripping their values, and proving a changed signal reaches Go through the main loop.

License

BSD-3-Clause. See LICENSE.

Documentation

Index

• Constants
• Variables
• func IdleAdd(func())
• func Init() (bool, error)
• func TextureFromRGBA([]byte, int, int) uintptr
• type MainLoop
  • func MainLoopNew() MainLoop
  • func (l MainLoop) Quit()
  • func (l MainLoop) Run()
• type Picture
  • func PictureNew() Picture
  • func (p Picture) SetRGBA([]byte, int, int)
  • func (p Picture) Widget() Widget
• type Widget
  • func ButtonNewWithLabel(string) Widget
  • func CheckButtonNewWithLabel(string) Widget
  • func DrawingAreaNew() Widget
  • func EntryNew() Widget
  • func FixedNew() Widget
  • func LabelNew(string) Widget
  • func WindowNew() Widget
  • func (w Widget) Active() bool
  • func (w Widget) AddTickCallback(func() bool) uint64
  • func (w Widget) Connect(string, func()) uint64
  • func (f Widget) Move(Widget, float64, float64)
  • func (w Widget) Present()
  • func (f Widget) Put(Widget, float64, float64)
  • func (w Widget) QueueDraw()
  • func (w Widget) SetActive(bool)
  • func (w Widget) SetChild(Widget)
  • func (w Widget) SetDefaultSize(int, int)
  • func (w Widget) SetLabel(string)
  • func (w Widget) SetSizeRequest(int, int)
  • func (w Widget) SetText(string)
  • func (w Widget) SetTitle(string)
  • func (w Widget) SetVisibility(bool)
  • func (w Widget) SetVisible(bool)
  • func (w Widget) Text() string
  • func (w Widget) Unparent()

Constants

const MemoryR8G8B8A8 = 5

MemoryR8G8B8A8 is the GdkMemoryFormat for a go-widgets RGBA frame; defined here too so consumer code naming it compiles off Linux.

Variables

var ErrUnsupported = errors.New("gtk4: only available on Linux")

ErrUnsupported is returned by Init on any platform without GTK4 (everything but Linux). It is defined on every platform so a portable consumer can test for it with errors.Is.

Functions

func IdleAdd

func IdleAdd(func())

func Init

func Init() (bool, error)

Init reports ErrUnsupported off Linux.

func TextureFromRGBA

func TextureFromRGBA([]byte, int, int) uintptr

Types

type MainLoop

type MainLoop uintptr

MainLoop is a GLib main loop. Off Linux it does nothing.

func MainLoopNew

func MainLoopNew() MainLoop

func (MainLoop) Quit

func (l MainLoop) Quit()

func (MainLoop) Run

func (l MainLoop) Run()

type Picture

type Picture uintptr

Picture is a GtkPicture showing an RGBA frame. Off Linux it does nothing.

func PictureNew

func PictureNew() Picture

func (Picture) SetRGBA

func (p Picture) SetRGBA([]byte, int, int)

func (Picture) Widget

func (p Picture) Widget() Widget

type Widget

type Widget uintptr

Widget is a GTK widget. Off Linux no real one is ever created.

func ButtonNewWithLabel

func ButtonNewWithLabel(string) Widget

func CheckButtonNewWithLabel

func CheckButtonNewWithLabel(string) Widget

func DrawingAreaNew

func DrawingAreaNew() Widget

func EntryNew

func EntryNew() Widget

func FixedNew

func FixedNew() Widget

func LabelNew

func LabelNew(string) Widget

func WindowNew

func WindowNew() Widget

The constructors return the null widget off Linux; the methods are no-ops or zero, so consumer code that names them still compiles.

func (Widget) Active

func (w Widget) Active() bool

func (Widget) AddTickCallback

func (w Widget) AddTickCallback(func() bool) uint64

func (Widget) Connect

func (w Widget) Connect(string, func()) uint64

func (Widget) Move

func (f Widget) Move(Widget, float64, float64)

func (Widget) Present

func (w Widget) Present()

func (Widget) Put

func (f Widget) Put(Widget, float64, float64)

func (Widget) QueueDraw

func (w Widget) QueueDraw()

func (Widget) SetActive

func (w Widget) SetActive(bool)

func (Widget) SetChild

func (w Widget) SetChild(Widget)

func (Widget) SetDefaultSize

func (w Widget) SetDefaultSize(int, int)

func (Widget) SetLabel

func (w Widget) SetLabel(string)

func (Widget) SetSizeRequest

func (w Widget) SetSizeRequest(int, int)

func (Widget) SetText

func (w Widget) SetText(string)

func (Widget) SetTitle

func (w Widget) SetTitle(string)

func (Widget) SetVisibility

func (w Widget) SetVisibility(bool)

func (Widget) SetVisible

func (w Widget) SetVisible(bool)

func (Widget) Text

func (w Widget) Text() string

func (Widget) Unparent

func (w Widget) Unparent()