forked from joejulian/gio
Gordon Klaus
114 lines
2.7 KiB
Go
114 lines
2.7 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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package material
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import (
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"image"
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"image/color"
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"gioui.org/internal/f32color"
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"gioui.org/layout"
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"gioui.org/op"
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"gioui.org/op/clip"
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"gioui.org/op/paint"
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"gioui.org/unit"
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"gioui.org/widget"
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)
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// Slider is for selecting a value in a range.
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func Slider(th *Theme, float *widget.Float, min, max float32) SliderStyle {
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return SliderStyle{
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Min: min,
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Max: max,
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Color: th.Palette.ContrastBg,
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Float: float,
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FingerSize: th.FingerSize,
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}
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}
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type SliderStyle struct {
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Axis layout.Axis
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Min, Max float32
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Invert bool
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Color color.NRGBA
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Float *widget.Float
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FingerSize unit.Dp
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}
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func (s SliderStyle) Layout(gtx layout.Context) layout.Dimensions {
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thumbRadius := gtx.Dp(6)
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trackWidth := gtx.Dp(2)
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axis := s.Axis
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// Keep a minimum length so that the track is always visible.
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minLength := thumbRadius + 3*thumbRadius + thumbRadius
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// Try to expand to finger size, but only if the constraints
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// allow for it.
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touchSizePx := min(gtx.Dp(s.FingerSize), axis.Convert(gtx.Constraints.Max).Y)
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sizeMain := max(axis.Convert(gtx.Constraints.Min).X, minLength)
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sizeCross := max(2*thumbRadius, touchSizePx)
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size := axis.Convert(image.Pt(sizeMain, sizeCross))
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o := axis.Convert(image.Pt(thumbRadius, 0))
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trans := op.Offset(o).Push(gtx.Ops)
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gtx.Constraints.Min = axis.Convert(image.Pt(sizeMain-2*thumbRadius, sizeCross))
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s.Float.Layout(gtx, axis, s.Min, s.Max, s.Invert, thumbRadius)
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gtx.Constraints.Min = gtx.Constraints.Min.Add(axis.Convert(image.Pt(0, sizeCross)))
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thumbPos := thumbRadius + int(s.Float.Pos())
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trans.Pop()
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color := s.Color
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if gtx.Queue == nil {
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color = f32color.Disabled(color)
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}
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rect := func(minx, miny, maxx, maxy int) image.Rectangle {
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r := image.Rect(minx, miny, maxx, maxy)
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if s.Invert != (axis == layout.Vertical) {
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r.Max.X, r.Min.X = sizeMain-r.Min.X, sizeMain-r.Max.X
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}
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r.Min = axis.Convert(r.Min)
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r.Max = axis.Convert(r.Max)
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return r
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}
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// Draw track before thumb.
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track := rect(
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thumbRadius, sizeCross/2-trackWidth/2,
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thumbPos, sizeCross/2+trackWidth/2,
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)
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paint.FillShape(gtx.Ops, color, clip.Rect(track).Op())
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// Draw track after thumb.
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track = rect(
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thumbPos, axis.Convert(track.Min).Y,
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sizeMain-thumbRadius, axis.Convert(track.Max).Y,
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)
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paint.FillShape(gtx.Ops, f32color.MulAlpha(color, 96), clip.Rect(track).Op())
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// Draw thumb.
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pt := image.Pt(thumbPos, sizeCross/2)
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thumb := rect(
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pt.X-thumbRadius, pt.Y-thumbRadius,
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pt.X+thumbRadius, pt.Y+thumbRadius,
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)
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paint.FillShape(gtx.Ops, color, clip.Ellipse(thumb).Op(gtx.Ops))
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return layout.Dimensions{Size: size}
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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