mirror of
https://git.sr.ht/~eliasnaur/gio
synced 2026-07-01 07:35:40 +00:00
Elias Naur
131 lines
2.8 KiB
Go
131 lines
2.8 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
|
|
|
|
package material
|
|
|
|
import (
|
|
"image"
|
|
"image/color"
|
|
"math"
|
|
"time"
|
|
|
|
"gioui.org/f32"
|
|
"gioui.org/layout"
|
|
"gioui.org/op"
|
|
"gioui.org/op/clip"
|
|
"gioui.org/op/paint"
|
|
"gioui.org/unit"
|
|
)
|
|
|
|
type LoaderStyle struct {
|
|
Color color.RGBA
|
|
}
|
|
|
|
func Loader(th *Theme) LoaderStyle {
|
|
return LoaderStyle{
|
|
Color: th.Color.Primary,
|
|
}
|
|
}
|
|
|
|
func (l LoaderStyle) Layout(gtx layout.Context) layout.Dimensions {
|
|
diam := gtx.Constraints.Min.X
|
|
if minY := gtx.Constraints.Min.Y; minY > diam {
|
|
diam = minY
|
|
}
|
|
if diam == 0 {
|
|
diam = gtx.Px(unit.Dp(24))
|
|
}
|
|
sz := gtx.Constraints.Constrain(image.Pt(diam, diam))
|
|
radius := float64(sz.X) * .5
|
|
defer op.Push(gtx.Ops).Pop()
|
|
op.Offset(f32.Pt(float32(radius), float32(radius))).Add(gtx.Ops)
|
|
|
|
dt := (time.Duration(gtx.Now.UnixNano()) % (time.Second)).Seconds()
|
|
startAngle := dt * math.Pi * 2
|
|
endAngle := startAngle + math.Pi*1.5
|
|
|
|
clipLoader(gtx.Ops, startAngle, endAngle, radius)
|
|
paint.ColorOp{
|
|
Color: l.Color,
|
|
}.Add(gtx.Ops)
|
|
op.Offset(f32.Pt(-float32(radius), -float32(radius))).Add(gtx.Ops)
|
|
paint.PaintOp{
|
|
Rect: f32.Rectangle{Max: layout.FPt(sz)},
|
|
}.Add(gtx.Ops)
|
|
op.InvalidateOp{}.Add(gtx.Ops)
|
|
return layout.Dimensions{
|
|
Size: sz,
|
|
}
|
|
}
|
|
|
|
func clipLoader(ops *op.Ops, start, end, radius float64) {
|
|
const thickness = .2
|
|
|
|
outer := float32(radius)
|
|
inner := float32(radius) * (1. - thickness)
|
|
|
|
var p clip.Path
|
|
p.Begin(ops)
|
|
|
|
sine, cose := math.Sincos(start)
|
|
|
|
pen := f32.Pt(float32(cose), float32(sine)).Mul(outer)
|
|
p.Move(pen)
|
|
angle := start
|
|
// The clip path uses quadratic beziér curves to approximate
|
|
// a circle arc. Minimize the error by capping the length of
|
|
// each curve segment.
|
|
arcPrRadian := radius * math.Pi
|
|
const maxArcLen = 20.
|
|
anglePerSegment := maxArcLen / arcPrRadian
|
|
// Outer arc.
|
|
for angle < end {
|
|
angle += anglePerSegment
|
|
if angle > end {
|
|
angle = end
|
|
}
|
|
sins, coss := sine, cose
|
|
sine, cose = math.Sincos(angle)
|
|
|
|
// https://pomax.github.io/bezierinfo/#circles
|
|
div := 1. / (coss*sine - cose*sins)
|
|
ctrl := f32.Point{
|
|
X: float32((sine - sins) * div),
|
|
Y: -float32((cose - coss) * div),
|
|
}.Mul(outer)
|
|
|
|
endPt := f32.Pt(float32(cose), float32(sine)).Mul(outer)
|
|
|
|
p.Quad(ctrl.Sub(pen), endPt.Sub(pen))
|
|
pen = endPt
|
|
}
|
|
|
|
// Arc cap.
|
|
cap := f32.Pt(float32(cose), float32(sine)).Mul(inner)
|
|
p.Line(cap.Sub(pen))
|
|
pen = cap
|
|
|
|
// Inner arc.
|
|
for angle > start {
|
|
angle -= anglePerSegment
|
|
if angle < start {
|
|
angle = start
|
|
}
|
|
sins, coss := sine, cose
|
|
sine, cose = math.Sincos(angle)
|
|
|
|
div := 1. / (coss*sine - cose*sins)
|
|
ctrl := f32.Point{
|
|
X: float32((sine - sins) * div),
|
|
Y: -float32((cose - coss) * div),
|
|
}.Mul(inner)
|
|
|
|
endPt := f32.Pt(float32(cose), float32(sine)).Mul(inner)
|
|
|
|
p.Quad(ctrl.Sub(pen), endPt.Sub(pen))
|
|
pen = endPt
|
|
}
|
|
|
|
// Second arc cap automatically completed by End.
|
|
p.End().Add(ops)
|
|
}
|