Added an image struct

image.go

@@ -0,0 +1,85 @@
+package stone
+
+import "image"
+import "image/color"
+
+type ColorImage struct {
+	x,           y            int
+	width,       height       int
+	bufferWidth, bufferHeight int
+	cellWidth,   cellHeight   int
+	buffer []color.RGBA
+
+	clean bool
+}
+
+func (im *ColorImage) Model () (model color.Model) {
+	model = color.RGBAModel
+	return
+}
+
+func (im *ColorImage) Bounds () (bounds image.Rectangle) {
+	bounds.Max.X = im.width
+	bounds.Max.Y = im.height
+	return
+}
+
+func (im *ColorImage) Size () (width, height int) {
+	width  = im.width
+	height = im.height
+	return
+}
+
+func (im *ColorImage) SetSize (width, height int) {
+	im.width  = width
+	im.height = height
+	im.bufferWidth  = im.cellWidth  * im.width
+	im.bufferHeight = im.cellHeight * im.height
+	im.buffer = make([]color.RGBA, im.bufferWidth * im.bufferHeight)
+	im.clean = false
+}
+
+func (im *ColorImage) At (x, y int) (pixel color.Color) {
+	if im.outOfBounds(x, y) { return }
+	pixel = im.buffer[x + y * im.width]
+	return
+}
+
+func (im *ColorImage) AtRGBA (x, y int) (pixel color.RGBA) {
+	if im.outOfBounds(x, y) { return }
+	pixel = im.buffer[x + y * im.width]
+	return
+}
+
+func (im *ColorImage) Set (x, y int, pixel color.Color) {
+	if im.outOfBounds(x, y) { return }
+	r, g, b, a := pixel.RGBA()
+	im.buffer[x + y * im.width] = color.RGBA {
+		R: uint8(r >> 8),
+		G: uint8(g >> 8),
+		B: uint8(b >> 8),
+		A: uint8(a >> 8),
+	}
+
+	im.clean = false
+	return
+}
+
+func (im *ColorImage) SetRGBA (x, y int, pixel color.RGBA) {
+	if im.outOfBounds(x, y) { return }
+	im.buffer[x + y * im.width] = pixel
+	return
+}
+
+func (im *ColorImage) MarkClean () {
+	im.clean = true
+}
+
+func (im *ColorImage) outOfBounds (x, y int) (outOfBounds bool) {
+	outOfBounds =
+		x >= im.width  ||
+		y >= im.height ||
+		x < 0 ||
+		y < 0
+	return
+}