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// 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 Event 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.Event()
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 := new(app.Window)
for {
w.Event()
}
}()
app.Main()
}
# Events
The [Events] iterator yields app-specific events such as [URLEvent]. [Window.Event]
yields events that target a particular window.
On Windows, macOS, Wayland, and X11, [Window.Event] yields a [ClosingEvent]
when the user requests to close a window. The window closes unless the
application calls [ClosingEvent.Abort] while handling the event.
# iOS
Gio programs need iOS 13 or tvOS 13 and run with the UIScene life cycle.
The Info.plist of the app must contain a UIApplicationSceneManifest, which
needs no scene configurations; the gogio tool adds it. Without it, the app
starts without a window.
# 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