90 lines
2.8 KiB
Go
90 lines
2.8 KiB
Go
package patterns
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import "image"
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import "tomo/artist"
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// Border is a pattern that behaves similarly to border-image in CSS. It divides
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// a source canvas into nine sections...
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//
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// Inset[1]
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// ┌──┴──┐
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// ┌─┌─────┬─────┬─────┐
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// Inset[0]─┤ │ 0 │ 1 │ 2 │
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// └─├─────┼─────┼─────┤
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// │ 3 │ 4 │ 5 │
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// ├─────┼─────┼─────┤─┐
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// │ 6 │ 7 │ 8 │ ├─Inset[2]
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// └─────┴─────┴─────┘─┘
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// └──┬──┘
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// Inset[3]
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//
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// ... Where the bounds of section 4 are defined as the application of the
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// pattern's inset to the canvas's bounds. The bounds of the other eight
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// sections are automatically sized around it.
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//
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// When drawn to a destination canvas, the bounds of sections 1, 3, 4, 5, and 7
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// are expanded or contracted to fit the given drawing bounds. All sections are
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// rendered as if they are Texture patterns, meaning these flexible sections
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// will repeat to fill in any empty space.
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//
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// This pattern can be used to make a static image texture into something that
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// responds well to being resized.
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type Border struct {
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artist.Canvas
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artist.Inset
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}
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// Draw draws the border pattern onto the destination canvas within the given
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// bounds.
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func (pattern Border) Draw (destination artist.Canvas, bounds image.Rectangle) {
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drawBounds := bounds.Canon().Intersect(destination.Bounds())
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if drawBounds.Empty() { return }
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srcSections := nonasect(pattern.Bounds(), pattern.Inset)
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srcTextures := [9]Texture { }
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for index, section := range srcSections {
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srcTextures[index].Canvas = artist.Cut(pattern, section)
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}
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dstSections := nonasect(bounds, pattern.Inset)
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for index, section := range dstSections {
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srcTextures[index].Draw(destination, section)
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}
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}
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func nonasect (bounds image.Rectangle, inset artist.Inset) [9]image.Rectangle {
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center := inset.Apply(bounds)
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return [9]image.Rectangle {
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// top
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image.Rectangle {
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bounds.Min,
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center.Min },
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image.Rect (
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center.Min.X, bounds.Min.Y,
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center.Max.X, center.Min.Y),
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image.Rect (
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center.Max.X, bounds.Min.Y,
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bounds.Max.X, center.Min.Y),
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// center
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image.Rect (
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bounds.Min.X, center.Min.Y,
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center.Min.X, center.Max.Y),
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center,
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image.Rect (
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center.Max.X, center.Min.Y,
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bounds.Max.X, center.Max.Y),
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// bottom
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image.Rect (
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bounds.Min.X, center.Max.Y,
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center.Min.X, bounds.Max.Y),
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image.Rect (
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center.Min.X, center.Max.Y,
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center.Max.X, bounds.Max.Y),
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image.Rect (
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center.Max.X, center.Max.Y,
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bounds.Max.X, bounds.Max.Y),
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}
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}
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