ADT/Layoutlib: implement Canvas.concat(Matrix)

This prevented ImageView from making proper use of ScaleType.

Also fixed Canvas.getSaveCount() that returned the wrong
value and Matrix.getTransform() which used the wrong order
for the AffineTransform constructor!!

Bug: 2364564

Change-Id: I78babf4aa6689440e52ad06b1473f75b20eb66da

tools/layoutlib/bridge/src/android/graphics/Canvas.java

@@ -236,10 +236,15 @@ public class Canvas extends _Original_Canvas {
      */
     @Override
     public int save() {
+        // get the current save count
+        int count = mGraphicsStack.size();
+
+        // create a new graphics and add it to the stack
         Graphics2D g = (Graphics2D)getGraphics2d().create();
         mGraphicsStack.push(g);
 
-        return mGraphicsStack.size() - 1;
+        // return the old save count
+        return count;
     }
 
     /* (non-Javadoc)
@@ -274,10 +279,9 @@ public class Canvas extends _Original_Canvas {
      */
     @Override
     public int getSaveCount() {
-        return mGraphicsStack.size() - 1;
+        return mGraphicsStack.size();
     }
 
-
     /* (non-Javadoc)
      * @see android.graphics.Canvas#clipRect(float, float, float, float, android.graphics.Region.Op)
      */
@@ -953,10 +957,6 @@ public class Canvas extends _Original_Canvas {
      */
     @Override
     public void setMatrix(Matrix matrix) {
-        // since SetMatrix *replaces* all the other transformation, we have to restore/save
-        restore();
-        save();
-
         // get the new current graphics
         Graphics2D g = getGraphics2d();
 
@@ -968,6 +968,27 @@ public class Canvas extends _Original_Canvas {
         }
     }
 
+    /* (non-Javadoc)
+     * @see android.graphics.Canvas#concat(android.graphics.Matrix)
+     */
+    @Override
+    public void concat(Matrix matrix) {
+        // get the current top graphics2D object.
+        Graphics2D g = getGraphics2d();
+
+        // get its current matrix
+        AffineTransform currentTx = g.getTransform();
+        // get the AffineTransform of the given matrix
+        AffineTransform matrixTx = matrix.getTransform();
+
+        // combine them so that the given matrix is applied after.
+        currentTx.preConcatenate(matrixTx);
+
+        // give it to the graphics2D as a new matrix replacing all previous transform
+        g.setTransform(currentTx);
+    }
+
+
     // --------------------
 
     /* (non-Javadoc)
@@ -1007,15 +1028,6 @@ public class Canvas extends _Original_Canvas {
         return super.clipRegion(region);
     }
 
-    /* (non-Javadoc)
-     * @see android.graphics.Canvas#concat(android.graphics.Matrix)
-     */
-    @Override
-    public void concat(Matrix matrix) {
-        // TODO Auto-generated method stub
-        super.concat(matrix);
-    }
-
     /* (non-Javadoc)
      * @see android.graphics.Canvas#drawArc(android.graphics.RectF, float, float, boolean, android.graphics.Paint)
      */

tools/layoutlib/bridge/src/android/graphics/Matrix.java

@@ -87,8 +87,12 @@ public class Matrix extends _Original_Matrix {
     }
 
     public AffineTransform getTransform() {
-        return new AffineTransform(mValues[0], mValues[1], mValues[2],
-                mValues[3], mValues[4], mValues[5]);
+        // the AffineTransform constructor takes the value in a different order
+        // for a matrix [ 0 1 2 ]
+        //              [ 3 4 5 ]
+        // the order is 0, 3, 1, 4, 2, 5...
+        return new AffineTransform(mValues[0], mValues[3], mValues[1],
+                mValues[4], mValues[2], mValues[5]);
     }
 
     public boolean hasPerspective() {