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Diffstat (limited to 'vendor/github.com/llgcode/draw2d/draw2dbase/line.go')
-rw-r--r--vendor/github.com/llgcode/draw2d/draw2dbase/line.go58
1 files changed, 58 insertions, 0 deletions
diff --git a/vendor/github.com/llgcode/draw2d/draw2dbase/line.go b/vendor/github.com/llgcode/draw2d/draw2dbase/line.go
new file mode 100644
index 0000000..a83bbc3
--- /dev/null
+++ b/vendor/github.com/llgcode/draw2d/draw2dbase/line.go
@@ -0,0 +1,58 @@
+// Copyright 2011 The draw2d Authors. All rights reserved.
+// created: 27/05/2011 by Laurent Le Goff
+
+package draw2dbase
+
+import (
+ "image/color"
+ "image/draw"
+)
+
+func abs(i int) int {
+ if i < 0 {
+ return -i
+ }
+ return i
+}
+
+// PolylineBresenham draws a polyline to an image
+func PolylineBresenham(img draw.Image, c color.Color, s ...float64) {
+ for i := 2; i < len(s); i += 2 {
+ Bresenham(img, c, int(s[i-2]+0.5), int(s[i-1]+0.5), int(s[i]+0.5), int(s[i+1]+0.5))
+ }
+}
+
+// Bresenham draws a line between (x0, y0) and (x1, y1)
+func Bresenham(img draw.Image, color color.Color, x0, y0, x1, y1 int) {
+ dx := abs(x1 - x0)
+ dy := abs(y1 - y0)
+ var sx, sy int
+ if x0 < x1 {
+ sx = 1
+ } else {
+ sx = -1
+ }
+ if y0 < y1 {
+ sy = 1
+ } else {
+ sy = -1
+ }
+ err := dx - dy
+
+ var e2 int
+ for {
+ img.Set(x0, y0, color)
+ if x0 == x1 && y0 == y1 {
+ return
+ }
+ e2 = 2 * err
+ if e2 > -dy {
+ err = err - dy
+ x0 = x0 + sx
+ }
+ if e2 < dx {
+ err = err + dx
+ y0 = y0 + sy
+ }
+ }
+}