110 lines
2.8 KiB
Go
Executable file
110 lines
2.8 KiB
Go
Executable file
package xmobilebackend
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import (
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"runtime"
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"github.com/tfriedel6/canvas/backend/backendbase"
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"golang.org/x/mobile/gl"
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)
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// LinearGradient is a gradient with any number of
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// stops and any number of colors. The gradient will
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// be drawn such that each point on the gradient
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// will correspond to a straight line
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type LinearGradient struct {
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gradient
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}
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// RadialGradient is a gradient with any number of
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// stops and any number of colors. The gradient will
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// be drawn such that each point on the gradient
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// will correspond to a circle
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type RadialGradient struct {
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gradient
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}
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type gradient struct {
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b *XMobileBackend
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tex gl.Texture
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loaded bool
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}
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func (b *XMobileBackend) LoadLinearGradient(data backendbase.Gradient) backendbase.LinearGradient {
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b.activate()
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lg := &LinearGradient{
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gradient: gradient{b: b},
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}
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lg.tex = b.glctx.CreateTexture()
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b.glctx.ActiveTexture(gl.TEXTURE0)
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b.glctx.BindTexture(gl.TEXTURE_2D, lg.tex)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
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lg.load(data)
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runtime.SetFinalizer(lg, func(lg *LinearGradient) {
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b.glChan <- func() {
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b.glctx.DeleteTexture(lg.tex)
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}
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})
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return lg
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}
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func (b *XMobileBackend) LoadRadialGradient(data backendbase.Gradient) backendbase.RadialGradient {
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b.activate()
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rg := &RadialGradient{
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gradient: gradient{b: b},
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}
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rg.tex = b.glctx.CreateTexture()
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b.glctx.ActiveTexture(gl.TEXTURE0)
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b.glctx.BindTexture(gl.TEXTURE_2D, rg.tex)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
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b.glctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
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rg.load(data)
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runtime.SetFinalizer(rg, func(rg *RadialGradient) {
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b.glChan <- func() {
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b.glctx.DeleteTexture(rg.tex)
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}
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})
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return rg
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}
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// Delete explicitly deletes the gradient
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func (g *gradient) Delete() {
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b := g.b
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g.b.activate()
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b.glctx.DeleteTexture(g.tex)
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}
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func (lg *LinearGradient) Replace(data backendbase.Gradient) { lg.load(data) }
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func (rg *RadialGradient) Replace(data backendbase.Gradient) { rg.load(data) }
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func (g *gradient) load(stops backendbase.Gradient) {
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b := g.b
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if g.loaded {
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return
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}
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g.b.activate()
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b.glctx.ActiveTexture(gl.TEXTURE0)
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b.glctx.BindTexture(gl.TEXTURE_2D, g.tex)
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var pixels [2048 * 4]byte
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pp := 0
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for i := 0; i < 2048; i++ {
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c := stops.ColorAt(float64(i) / 2047)
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pixels[pp] = c.R
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pixels[pp+1] = c.G
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pixels[pp+2] = c.B
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pixels[pp+3] = c.A
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pp += 4
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}
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b.glctx.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 2048, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixels[0:])
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g.loaded = true
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}
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