47 lines
1.1 KiB
Go
47 lines
1.1 KiB
Go
package text
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import (
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"github.com/egoist/mygo/ui"
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"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
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)
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type MarqueeOptions struct {
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// Width is the window in dots; zero means 120.
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Width int
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Slot pixel.Slot
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}
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type marqueeKey struct{}
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type marqueeState struct{ offset, last int }
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// Marquee scrolls s a dot a step; hover pauses it.
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func Marquee(c *ui.Context, s string, o MarqueeOptions) *ui.Element {
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k := pixel.K(c)
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w := pixel.Or("Marquee Width", o.Width, 120)
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e := ui.Box(c).Size(k.D(w), k.D(pixel.LineHeight)).Clip().Label(s).Role(ui.RoleText)
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ms := ui.Local(e, marqueeKey{}, func() marqueeState { return marqueeState{last: -1} })
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if k.Reduce() || e.Hovered() {
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ms.last = -1
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} else {
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step := k.Tick(c, 20)
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if ms.last >= 0 {
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ms.offset += step - ms.last
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}
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ms.last = step
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}
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period := w + pixel.Measure(s)
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x := -(ms.offset % period)
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if k.Reduce() {
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x = 0
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}
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return e.Draw(func(p *ui.Painter, r ui.Rect) {
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g := k.Canvas(p, r)
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g.Clip(0, 0, w, pixel.LineHeight, func() {
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g.Text(x, 0, s, o.Slot, 1)
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g.Text(x+period, 0, s, o.Slot, 1)
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})
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})
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}
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