34 lines
817 B
Go
34 lines
817 B
Go
package text
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import (
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"math"
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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 WaveTextOptions struct {
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Slot pixel.Slot
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Scale int
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// Amp is the bob in dots; zero means 2.
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Amp int
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}
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// WaveText bobs characters on a sine wave at 10 fps.
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func WaveText(c *ui.Context, s string, o WaveTextOptions) *ui.Element {
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k, sc := pixel.K(c), scale(o.Scale)
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amp := pixel.Or("WaveText Amp", o.Amp, 2)
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return block(c, k, s, pixel.Measure(s)*sc, pixel.LineHeight*sc+2*amp, func(g pixel.Canvas) {
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step := g.Step(10)
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each(s, sc, func(i int, r rune, x int) {
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g.Text(x, amp+wave(amp, step+i), string(r), o.Slot, sc)
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})
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})
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}
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// wave is the bob at step n of an 8-cycle.
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func wave(amp, n int) int {
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return int(math.Round(float64(amp) * math.Sin(float64(n%8)*math.Pi/4)))
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}
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