gio/app/doc.go

// SPDX-License-Identifier: Unlicense OR MIT

/*
Package app provides a platform-independent interface to operating system
functionality for running graphical user interfaces.

See https://gioui.org for instructions to set up and run Gio programs.

# Windows

A Window is run by calling its NextEvent method in a loop. The first time a
method on Window is called, a new GUI window is created and shown. On mobile
platforms or when Gio is embedded in another project, Window merely connects
with a previously created GUI window.

The most important event is [FrameEvent] that prompts an update of the window
contents.

For example:

	w := new(app.Window)
	for {
		e := w.NextEvent()
		if e, ok := e.(app.FrameEvent); ok {
			ops.Reset()
			// Add operations to ops.
			...
			// Completely replace the window contents and state.
			e.Frame(ops)
		}
	}

A program must keep receiving events from the event channel until
[DestroyEvent] is received.

# Main

The Main function must be called from a program's main function, to hand over
control of the main thread to operating systems that need it.

Because Main is also blocking on some platforms, the event loop of a Window must run in a goroutine.

For example, to display a blank but otherwise functional window:

	package main

	import "gioui.org/app"

	func main() {
		go func() {
			w := app.NewWindow()
			for {
				w.NextEvent()
			}
		}()
		app.Main()
	}

# Permissions

The packages under gioui.org/app/permission should be imported
by a Gio program or by one of its dependencies to indicate that specific
operating-system permissions are required.  Please see documentation for
package gioui.org/app/permission for more information.
*/
package app