Files
gio/widget/material/loader.go
T
Chris Waldon a87a520ae8 widget/material: manage widget colors with Palette type
This introduces a new material.Palette type that captures the color information
necessary to render a widget. This type is embedded in the material.Theme to
make it easier to swap to a different palette for part of the UI by reassinging
the Palette field.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>
2020-12-06 23:02:30 +01:00

82 lines
1.6 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.NRGBA
}
func Loader(th *Theme) LoaderStyle {
return LoaderStyle{
Color: th.Palette.ContrastBg,
}
}
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{}.Add(gtx.Ops)
op.InvalidateOp{}.Add(gtx.Ops)
return layout.Dimensions{
Size: sz,
}
}
func clipLoader(ops *op.Ops, startAngle, endAngle, radius float64) {
const thickness = .25
var (
width = float32(radius * thickness)
delta = float32(endAngle - startAngle)
vy, vx = math.Sincos(startAngle)
pen = f32.Pt(float32(vx), float32(vy)).Mul(float32(radius))
center = f32.Pt(0, 0).Sub(pen)
style = clip.StrokeStyle{
Cap: clip.FlatCap,
}
p clip.Path
)
p.Begin(ops)
p.Move(pen)
p.Arc(center, center, delta)
p.Stroke(width, style).Add(ops)
}