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Copy pathfloat.go
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99 lines (84 loc) · 2.1 KB
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// SPDX-License-Identifier: Unlicense OR MIT
package widget
import (
"image"
"gioui.org/gesture"
"gioui.org/io/pointer"
"gioui.org/layout"
"gioui.org/op/clip"
)
// Float is for selecting a value in a range.
type Float struct {
Value float32
Axis layout.Axis
drag gesture.Drag
pos float32 // position normalized to [0, 1]
length float32
changed bool
}
// Dragging returns whether the value is being interacted with.
func (f *Float) Dragging() bool { return f.drag.Dragging() }
// Layout updates the value according to drag events along the f's main axis.
//
// The range of f is set by the minimum constraints main axis value.
func (f *Float) Layout(gtx layout.Context, pointerMargin int, min, max float32) layout.Dimensions {
size := gtx.Constraints.Min
f.length = float32(f.Axis.Convert(size).X)
var de *pointer.Event
for _, e := range f.drag.Events(gtx.Metric, gtx, gesture.Axis(f.Axis)) {
if e.Type == pointer.Press || e.Type == pointer.Drag {
de = &e
}
}
value := f.Value
if de != nil {
xy := de.Position.X
if f.Axis == layout.Vertical {
xy = de.Position.Y
}
f.pos = xy / f.length
value = min + (max-min)*f.pos
} else if min != max {
f.pos = (value - min) / (max - min)
}
// Unconditionally call setValue in case min, max, or value changed.
f.setValue(value, min, max)
if f.pos < 0 {
f.pos = 0
} else if f.pos > 1 {
f.pos = 1
}
margin := f.Axis.Convert(image.Pt(pointerMargin, 0))
rect := image.Rectangle{
Min: margin.Mul(-1),
Max: size.Add(margin),
}
defer clip.Rect(rect).Push(gtx.Ops).Pop()
f.drag.Add(gtx.Ops)
return layout.Dimensions{Size: size}
}
func (f *Float) setValue(value, min, max float32) {
if min > max {
min, max = max, min
}
if value < min {
value = min
} else if value > max {
value = max
}
if f.Value != value {
f.Value = value
f.changed = true
}
}
// Pos reports the selected position.
func (f *Float) Pos() float32 {
return f.pos * f.length
}
// Changed reports whether the value has changed since
// the last call to Changed.
func (f *Float) Changed() bool {
changed := f.changed
f.changed = false
return changed
}