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// SPDX-License-Identifier: Unlicense OR MIT
// Package system contains events usually handled at the top-level
// program level.
package system
import (
"image"
"time"
"gioui.org/io/event"
"gioui.org/op"
"gioui.org/unit"
)
// A FrameEvent requests a new frame in the form of a list of
// operations that describes what to display and how to handle
// input.
type FrameEvent struct {
// Now is the current animation. Use Now instead of time.Now to
// synchronize animation and to avoid the time.Now call overhead.
Now time.Time
// Metric converts device independent dp and sp to device pixels.
Metric unit.Metric
// Size is the dimensions of the window.
Size image.Point
// Insets is the insets to apply.
Insets Insets
// Frame completes the FrameEvent by drawing the graphical operations
// from ops into the window.
Frame func(frame *op.Ops)
// Queue supplies the events for event handlers.
Queue event.Queue
}
// DestroyEvent is the last event sent through
// a window event channel.
type DestroyEvent struct {
// Err is nil for normal window closures. If a
// window is prematurely closed, Err is the cause.
Err error
}
// Insets is the space taken up by
// system decoration such as translucent
// system bars and software keyboards.
type Insets struct {
Top, Bottom, Left, Right unit.Value
}
// A StageEvent is generated whenever the stage of a
// Window changes.
type StageEvent struct {
Stage Stage
}
// CommandEvent is a system event. Unlike most other events, CommandEvent is
// delivered as a pointer to allow Cancel to suppress it.
type CommandEvent struct {
Type CommandType
// Cancel suppress the default action of the command.
Cancel bool
}
// Stage of a Window.
type Stage uint8
// CommandType is the type of a CommandEvent.
type CommandType uint8
const (
// StagePaused is the Stage for inactive Windows.
// Inactive Windows don't receive FrameEvents.
StagePaused Stage = iota
// StateRunning is for active Windows.
StageRunning
)
const (
// CommandBack is the command for a back action
// such as the Android back button.
CommandBack CommandType = iota
)
func (l Stage) String() string {
switch l {
case StagePaused:
return "StagePaused"
case StageRunning:
return "StageRunning"
default:
panic("unexpected Stage value")
}
}
func (FrameEvent) ImplementsEvent() {}
func (StageEvent) ImplementsEvent() {}
func (*CommandEvent) ImplementsEvent() {}
func (DestroyEvent) ImplementsEvent() {}
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