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