package shapes import "image" import "image/color" import "git.tebibyte.media/sashakoshka/tomo/canvas" // ColorLine draws a line from one point to another with the specified weight // and color. func ColorLine ( destination canvas.Canvas, color color.RGBA, weight int, min image.Point, max image.Point, ) ( updatedRegion image.Rectangle, ) { updatedRegion = image.Rectangle { Min: min, Max: max }.Canon() updatedRegion.Max.X ++ updatedRegion.Max.Y ++ data, stride := destination.Buffer() bounds := destination.Bounds() context := linePlottingContext { plottingContext: plottingContext { dstData: data, dstStride: stride, color: color, weight: weight, bounds: bounds, }, min: min, max: max, } if abs(max.Y - min.Y) < abs(max.X - min.X) { if max.X < min.X { context.swap() } context.lineLow() } else { if max.Y < min.Y { context.swap() } context.lineHigh() } return } type linePlottingContext struct { plottingContext min image.Point max image.Point } func (context *linePlottingContext) swap () { temp := context.max context.max = context.min context.min = temp } func (context linePlottingContext) lineLow () { deltaX := context.max.X - context.min.X deltaY := context.max.Y - context.min.Y yi := 1 if deltaY < 0 { yi = -1 deltaY *= -1 } D := (2 * deltaY) - deltaX point := context.min for ; point.X < context.max.X; point.X ++ { context.plotColor(point) if D > 0 { D += 2 * (deltaY - deltaX) point.Y += yi } else { D += 2 * deltaY } } } func (context linePlottingContext) lineHigh () { deltaX := context.max.X - context.min.X deltaY := context.max.Y - context.min.Y xi := 1 if deltaX < 0 { xi = -1 deltaX *= -1 } D := (2 * deltaX) - deltaY point := context.min for ; point.Y < context.max.Y; point.Y ++ { context.plotColor(point) if D > 0 { point.X += xi D += 2 * (deltaX - deltaY) } else { D += 2 * deltaX } } } func abs (n int) int { if n < 0 { n *= -1} return n }