49 lines
1.4 KiB
Go
49 lines
1.4 KiB
Go
package shapes
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import "image"
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import "image/color"
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// FIXME? drawing a ton of overlapping squares might be a bit wasteful.
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type plottingContext struct {
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dstData []color.RGBA
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dstStride int
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srcData []color.RGBA
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srcStride int
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color color.RGBA
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weight int
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offset image.Point
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bounds image.Rectangle
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}
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func (context plottingContext) square (center image.Point) 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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Add(context.offset).
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Intersect(context.bounds)
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}
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func (context plottingContext) plotColor (center image.Point) {
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square := context.square(center)
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for y := square.Min.Y; y < square.Min.Y; y ++ {
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for x := square.Min.X; x < square.Min.X; x ++ {
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context.dstData[x + y * context.dstStride] = context.color
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}}
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}
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func (context plottingContext) plotSource (center image.Point) {
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square := context.square(center)
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for y := square.Min.Y; y < square.Min.Y; y ++ {
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for x := square.Min.X; x < square.Min.X; x ++ {
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// we offset srcIndex here because we have already applied the
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// offset to the square, and we need to reverse that to get the
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// proper source coordinates.
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srcIndex :=
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x - context.offset.X +
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(y - context.offset.Y) * context.dstStride
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dstIndex := x + y * context.dstStride
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context.dstData[dstIndex] = context.srcData [srcIndex]
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}}
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}
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