add layout resize functions

1 files changed, 35 insertions, 0 deletions

diff --git a/layout/resize.go b/layout/resize.go
new file mode 100644
index 0000000..1d3d6f1
--- /dev/null
+++ b/layout/resize.go
@@ -0,0 +1,35 @@
+package layout
+
+import "image"
+
+// ResizeAll resizes a layout to consume all of its parent's area.
+func ResizeAll(r image.Rectangle) image.Rectangle { return r }
+
+// ResizeQuad1 resizes a layout to consume the top-right quadrant of its parent.
+func ResizeQuad1(r image.Rectangle) image.Rectangle {
+	mid := midpoint(r)
+	return image.Rect(mid.X, r.Min.Y, r.Max.X, mid.Y)
+}
+
+// ResizeQuad2 resizes a layout to consume the top-left quadrant of its parent.
+func ResizeQuad2(r image.Rectangle) image.Rectangle {
+	mid := midpoint(r)
+	return image.Rectangle{r.Min, mid}
+}
+
+// ResizeQuad3 resizes a layout to consume the bottom-left quadrant of its parent.
+func ResizeQuad3(r image.Rectangle) image.Rectangle {
+	mid := midpoint(r)
+	return image.Rect(r.Min.X, mid.Y, mid.X, r.Max.Y)
+}
+
+// ResizeQuad4 resizes a layout to consume the bottom-right quadrant of its parent.
+func ResizeQuad4(r image.Rectangle) image.Rectangle {
+	mid := midpoint(r)
+	return image.Rectangle{mid, r.Max}
+}
+
+// midpoint returns the point in the middle of a rectangle.
+func midpoint(r image.Rectangle) image.Point {
+	return r.Min.Add(r.Max).Div(2)
+}