109 lines
2.1 KiB
Go
109 lines
2.1 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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package gel
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import (
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"image"
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"gioui.org/gesture"
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"gioui.org/io/pointer"
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l "gioui.org/layout"
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"gioui.org/op/clip"
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)
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// Float is for selecting a value in a range.
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type Float struct {
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value float32
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drag gesture.Drag
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pos float32 // position normalized to [0, 1]
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length float32
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changed bool
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changeHook func(float32)
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}
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func (th *Theme) Float() *Float {
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return &Float{changeHook: func(float32) {}}
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}
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func (f *Float) SetValue(value float32) *Float {
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f.value = value
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return f
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}
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func (f *Float) Value() float32 {
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return f.value
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}
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func (f *Float) SetHook(fn func(fl float32)) *Float {
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f.changeHook = fn
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return f
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}
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// Fn processes events.
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func (f *Float) Fn(gtx l.Context, pointerMargin int, min, max float32) l.Dimensions {
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size := gtx.Constraints.Min
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f.length = float32(size.X)
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var de *pointer.Event
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for {
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ev, ok := f.drag.Update(gtx.Metric, gtx.Source, gesture.Horizontal)
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if !ok {
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break
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}
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if ev.Kind == pointer.Press || ev.Kind == pointer.Drag {
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de = &ev
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}
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if ev.Kind == pointer.Release {
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f.changeHook(f.value)
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}
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}
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value := f.value
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if de != nil {
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f.pos = de.Position.X / f.length
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value = min + (max-min)*f.pos
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} else if min != max {
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f.pos = value/(max-min) - min
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}
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// Unconditionally call setValue in case min, max, or value changed.
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f.setValue(value, min, max)
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if f.pos < 0 {
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f.pos = 0
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} else if f.pos > 1 {
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f.pos = 1
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}
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rect := image.Rectangle{Max: size}
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rect.Min.X -= pointerMargin
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rect.Max.X += pointerMargin
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defer clip.Rect(rect).Push(gtx.Ops).Pop()
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f.drag.Add(gtx.Ops)
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return l.Dimensions{Size: size}
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}
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func (f *Float) setValue(value, min, max float32) {
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if min > max {
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min, max = max, min
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}
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if value < min {
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value = min
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} else if value > max {
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value = max
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}
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if f.value != value {
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f.value = value
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f.changed = true
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}
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}
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// Pos reports the selected position.
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func (f *Float) Pos() float32 {
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return f.pos * f.length
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}
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// Changed reports whether the value has changed since the last call to Changed.
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func (f *Float) Changed() bool {
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changed := f.changed
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f.changed = false
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return changed
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}
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