+ /**
+ * @private Using the current viewBox property and the surface's width and height, calculate the
+ * appropriate viewBoxShift that will be applied as a persistent transform to all sprites.
+ */
+ applyViewBox: function() {
+ var me = this,
+ viewBox = me.viewBox,
+ width = me.width,
+ height = me.height,
+ viewBoxX, viewBoxY, viewBoxWidth, viewBoxHeight,
+ relativeHeight, relativeWidth, size;
+
+ if (viewBox && (width || height)) {
+ viewBoxX = viewBox.x;
+ viewBoxY = viewBox.y;
+ viewBoxWidth = viewBox.width;
+ viewBoxHeight = viewBox.height;
+ relativeHeight = height / viewBoxHeight;
+ relativeWidth = width / viewBoxWidth;
+
+ if (viewBoxWidth * relativeHeight < width) {
+ viewBoxX -= (width - viewBoxWidth * relativeHeight) / 2 / relativeHeight;
+ }
+ if (viewBoxHeight * relativeWidth < height) {
+ viewBoxY -= (height - viewBoxHeight * relativeWidth) / 2 / relativeWidth;
+ }
+
+ size = 1 / Math.min(viewBoxWidth, relativeHeight);
+
+ me.viewBoxShift = {
+ dx: -viewBoxX,
+ dy: -viewBoxY,
+ scale: size
+ };
+ }
+ },
+
+ transformToViewBox: function (x, y) {
+ if (this.viewBoxShift) {
+ var me = this, shift = me.viewBoxShift;
+ return [x * shift.scale - shift.dx, y * shift.scale - shift.dy];
+ } else {
+ return [x, y];
+ }
+ },
+