forked from joejulian/gio
Elias Naur
85 lines
1.7 KiB
Go
85 lines
1.7 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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"math"
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"time"
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"gioui.org/f32"
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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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)
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type LoaderStyle struct {
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Color color.NRGBA
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}
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func Loader(th *Theme) LoaderStyle {
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return LoaderStyle{
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Color: th.Palette.ContrastBg,
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}
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}
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func (l LoaderStyle) Layout(gtx layout.Context) layout.Dimensions {
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diam := gtx.Constraints.Min.X
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if minY := gtx.Constraints.Min.Y; minY > diam {
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diam = minY
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}
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if diam == 0 {
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diam = gtx.Px(unit.Dp(24))
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}
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sz := gtx.Constraints.Constrain(image.Pt(diam, diam))
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radius := float32(sz.X) * .5
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defer op.Save(gtx.Ops).Load()
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op.Offset(f32.Pt(radius, radius)).Add(gtx.Ops)
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dt := float32((time.Duration(gtx.Now.UnixNano()) % (time.Second)).Seconds())
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startAngle := dt * math.Pi * 2
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endAngle := startAngle + math.Pi*1.5
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clipLoader(gtx.Ops, startAngle, endAngle, radius)
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paint.ColorOp{
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Color: l.Color,
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}.Add(gtx.Ops)
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op.Offset(f32.Pt(-radius, -radius)).Add(gtx.Ops)
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paint.PaintOp{}.Add(gtx.Ops)
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op.InvalidateOp{}.Add(gtx.Ops)
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return layout.Dimensions{
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Size: sz,
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}
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}
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func clipLoader(ops *op.Ops, startAngle, endAngle, radius float32) {
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const thickness = .25
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var (
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width = radius * thickness
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delta = endAngle - startAngle
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vy, vx = math.Sincos(float64(startAngle))
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inner = radius * (1. - thickness*.5)
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pen = f32.Pt(float32(vx), float32(vy)).Mul(inner)
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center = f32.Pt(0, 0).Sub(pen)
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p clip.Path
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)
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p.Begin(ops)
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p.Move(pen)
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p.Arc(center, center, delta)
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clip.Stroke{
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Path: p.End(),
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Style: clip.StrokeStyle{
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Width: width,
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Cap: clip.FlatCap,
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},
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}.Op().Add(ops)
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}
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