Add DisplayObject#globalToLocal and DisplayObject#localToGlobal

Fixes #169
uxebu · Feb 4, 2013 · bf879ac · bf879ac
1 parent 3229320
commit bf879ac
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Showing 2 changed files with 88 additions and 1 deletion.
diff --git a/src/runner/display_object.js b/src/runner/display_object.js
@@ -673,6 +673,28 @@ define([
       };
     },
 
+    /**
+     * Transforms a point in global coordinate space to the local coordinate
+     * space of the display object.
+     *
+     * @param {Point} point
+     * @returns {Point}
+     */
+    globalToLocal: function(point) {
+      return this.getAbsoluteMatrix().transformPoint(point);
+    },
+
+    /**
+     * Transforms a point in the local coordinate space of the display object to
+     * the global coordinate space.
+     *
+     * @param {Point} point
+     * @returns {Point}
+     */
+    localToGlobal: function(point) {
+      return this.getAbsoluteMatrix().invert().transformPoint(point);
+    },
+
     /**
      * Destroys a child: removes it from the parent and removes all listeners.
      *

diff --git a/test/display_object-spec.js b/test/display_object-spec.js
@@ -4,9 +4,10 @@ define([
   'bonsai/event_emitter',
   'bonsai/runner/matrix',
   'bonsai/tools',
+  'bonsai/point',
   'common/mock',
   'common/displayobject-lifecycle'
-], function(DisplayObject, Group, EventEmitter, Matrix, tools, mock, testLifeCycle) {
+], function(DisplayObject, Group, EventEmitter, Matrix, tools, Point, mock, testLifeCycle) {
   describe('DisplayObject', function() {
     testLifeCycle(function() {
       return new DisplayObject();
@@ -409,5 +410,69 @@ define([
         //expect(spy.mostRecentCall.object).toBe(displayObject);
       });
     });
+
+    describe('globalToLocal', function() {
+      it('should apply the transform of an display object to a point', function() {
+        var point = new Point(-102, 23.75);
+        var matrix = new Matrix(1.0625, 0.3125, -1.25, -1.09375, 26.5, -34);
+        var displayObject = new DisplayObject().attr('matrix', matrix);
+
+        expect(displayObject.globalToLocal(point))
+          .toEqual(matrix.transformPoint(point));
+      });
+
+      it('should apply the computed transform of the display object and each parent', function() {
+        var point = new Point(-102, 23.75);
+        var matrix = new Matrix(1.375, -0.75, 1.328125, -0.15625, 41.75, -34.25);
+        var displayObject = new DisplayObject().attr('matrix', matrix);
+
+        var parent = new Group();
+        parent.addChild(displayObject);
+        var parentMatrix = new Matrix(1.9375, -1.609375, -1.609375, -0.078125, -15.5, -7);
+        parent.attr('matrix', parentMatrix);
+
+        var root = new Group();
+        root.addChild(parent);
+        var rootMatrix = new Matrix(-0.0625, 1.6875, -1.5, -1.421875, -14.5, 36.75);
+        root.attr('matrix', rootMatrix);
+
+        var absoluteMatrix = matrix.concat(parentMatrix).concat(rootMatrix);
+
+        expect(displayObject.globalToLocal(point))
+          .toEqual(absoluteMatrix.transformPoint(point));
+      });
+    });
+
+    describe('localToGlobal', function() {
+      it('should apply the inversed transform of an display object to a point', function() {
+        var point = new Point(-102, 23.75);
+        var matrix = new Matrix(1.0625, 0.3125, -1.25, -1.09375, 26.5, -34);
+        var displayObject = new DisplayObject().attr('matrix', matrix);
+
+        expect(displayObject.localToGlobal(point))
+          .toEqual(matrix.invert().transformPoint(point));
+      });
+
+      it('should apply the inverse computed transform of the display object and each parent', function() {
+        var point = new Point(-102, 23.75);
+        var matrix = new Matrix(1.375, -0.75, 1.328125, -0.15625, 41.75, -34.25);
+        var displayObject = new DisplayObject().attr('matrix', matrix);
+
+        var parent = new Group();
+        parent.addChild(displayObject);
+        var parentMatrix = new Matrix(1.9375, -1.609375, -1.609375, -0.078125, -15.5, -7);
+        parent.attr('matrix', parentMatrix);
+
+        var root = new Group();
+        root.addChild(parent);
+        var rootMatrix = new Matrix(-0.0625, 1.6875, -1.5, -1.421875, -14.5, 36.75);
+        root.attr('matrix', rootMatrix);
+
+        var absoluteMatrix = matrix.concat(parentMatrix).concat(rootMatrix);
+
+        expect(displayObject.localToGlobal(point))
+          .toEqual(absoluteMatrix.invert().transformPoint(point));
+      });
+    });
   });
 });