Files
gio/widget/example_test.go
T
Elias Naur 6f80b94b4a io/pointer,io/router: [API] make pass-through a property of AreaOp
We're about to make operation scopes explicit, which would result in
both AreaOp and PassOp be scoped. However, PassOp seems to light to have
its separate stack, so this change instead makes pass-through a property
of an area. We're assuming that clients that want pass-through are also
aware of the affected hit area.

API change: replace PassOps with the AreaOp.PassThrough field.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
2021-10-08 15:54:50 +02:00

73 lines
1.7 KiB
Go

// SPDX-License-Identifier: Unlicense OR MIT
package widget_test
import (
"fmt"
"image"
"gioui.org/f32"
"gioui.org/io/pointer"
"gioui.org/io/router"
"gioui.org/layout"
"gioui.org/op"
"gioui.org/widget"
)
func ExampleClickable_passthrough() {
// When laying out clickable widgets on top of each other,
// pointer events can be passed down for the underlying
// widgets to pick them up.
var button1, button2 widget.Clickable
var r router.Router
gtx := layout.Context{
Ops: new(op.Ops),
Constraints: layout.Exact(image.Pt(100, 100)),
Queue: &r,
}
// widget lays out two buttons on top of each other.
widget := func() {
button1.Layout(gtx)
area := pointer.Rect(image.Rectangle{Max: gtx.Constraints.Max})
// button2 completely covers button1, but pass-through allows pointer
// events to pass through to button1.
area.PassThrough = true
area.Add(gtx.Ops)
button2.Layout(gtx)
}
// The first layout and call to Frame declare the Clickable handlers
// to the input router, so the following pointer events are propagated.
widget()
r.Frame(gtx.Ops)
// Simulate one click on the buttons by sending a Press and Release event.
r.Queue(
pointer.Event{
Source: pointer.Mouse,
Buttons: pointer.ButtonPrimary,
Type: pointer.Press,
Position: f32.Pt(50, 50),
},
pointer.Event{
Source: pointer.Mouse,
Buttons: pointer.ButtonPrimary,
Type: pointer.Release,
Position: f32.Pt(50, 50),
},
)
// The second layout ensures that the click event is registered by the buttons.
widget()
if button1.Clicked() {
fmt.Println("button1 clicked!")
}
if button2.Clicked() {
fmt.Println("button2 clicked!")
}
// Output:
// button1 clicked!
// button2 clicked!
}