48 lines
1.4 KiB
Go
48 lines
1.4 KiB
Go
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package xcanvas
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import "image"
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import "github.com/jezek/xgbutil/xgraphics"
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type plottingContext struct {
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image *xgraphics.Image
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color xgraphics.BGRA
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weight int
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}
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func (context plottingContext) square (center image.Point) (square image.Rectangle) {
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return image.Rect(0, 0, context.weight, context.weight).
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Sub(image.Pt(context.weight / 2, context.weight / 2)).
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Add(center).
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Intersect(context.image.Bounds())
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}
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func (context plottingContext) plot (center image.Point) {
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square := context.square(center)
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if context.color.A == 255 {
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for y := square.Min.Y; y < square.Max.Y; y ++ {
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for x := square.Min.X; x < square.Max.X; x ++ {
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index := context.image.PixOffset(x, y)
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context.image.Pix[index + 0] = context.color.B
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context.image.Pix[index + 1] = context.color.G
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context.image.Pix[index + 2] = context.color.R
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context.image.Pix[index + 3] = context.color.A
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}}
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} else {
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for y := square.Min.Y; y < square.Max.Y; y ++ {
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for x := square.Min.X; x < square.Max.X; x ++ {
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index := context.image.PixOffset(x, y)
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pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
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B: context.image.Pix[index + 0],
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G: context.image.Pix[index + 1],
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R: context.image.Pix[index + 2],
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A: context.image.Pix[index + 3],
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}, context.color)
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context.image.Pix[index + 0] = pixel.B
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context.image.Pix[index + 1] = pixel.G
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context.image.Pix[index + 2] = pixel.R
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context.image.Pix[index + 3] = pixel.A
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}}
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}
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}
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