Make View transformation matrix updating more explicit.

The original code depends on side-effects of hasIdentityMatrix()
to update the View transformation matrix.  This change adds an
explicit updateMatrix() method to make it more explicit when
we are relying on the matrix having been updated.  Among other
things, getInverseMatrix() did not update the matrix so the
caller had to know to call hasIdentityMatrix() first (which was
always the case, but still potentially error-prone).

Change-Id: I16d56f60a785a15c65f73e57b9aded9e4e3bca55

1 files changed, 32 insertions, 17 deletions

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 00324a854dfd..011c3df23ca1 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -1683,7 +1683,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      * The transform matrix for the View. This transform is calculated internally
      * based on the rotation, scaleX, and scaleY properties. The identity matrix
      * is used by default. Do *not* use this variable directly; instead call
-     * getMatrix(), which will automatically recalculate the matrix if necessary
+     * getInverseMatrix(), which will automatically recalculate the matrix if necessary
      * to get the correct matrix based on the latest rotation and scale properties.
      */
     private Matrix mInverseMatrix;
@@ -1706,7 +1706,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      * A variable that tracks whether we need to recalculate the
      * transform matrix, based on whether the rotation or scaleX/Y properties
      * have changed since the matrix was last calculated. This variable
-     * is only valid after a call to getMatrix().
+     * is only valid after a call to updateMatrix() or to a function that
+     * calls it such as getMatrix(), hasIdentityMatrix() and getInverseMatrix().
      */
     private boolean mMatrixIsIdentity = true;
 
@@ -5118,7 +5119,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      * @return The current transform matrix for the view
      */
     public Matrix getMatrix() {
-        hasIdentityMatrix();
+        updateMatrix();
         return mMatrix;
     }
 
@@ -5133,11 +5134,20 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
     }
 
     /**
-     * Recomputes the transform matrix if necessary.
+     * Returns true if the transform matrix is the identity matrix.
+     * Recomputes the matrix if necessary.
      * 
      * @return True if the transform matrix is the identity matrix, false otherwise.
      */
-    boolean hasIdentityMatrix() {
+    final boolean hasIdentityMatrix() {
+        updateMatrix();
+        return mMatrixIsIdentity;
+    }
+
+    /**
+     * Recomputes the transform matrix if necessary.
+     */
+    private final void updateMatrix() {
         if (mMatrixDirty) {
             // transform-related properties have changed since the last time someone
             // asked for the matrix; recalculate it with the current values
@@ -5176,7 +5186,6 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
             mMatrixIsIdentity = mMatrix.isIdentity();
             mInverseMatrixDirty = true;
         }
-        return mMatrixIsIdentity;
     }
 
     /**
@@ -5186,7 +5195,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      *
      * @return The inverse of the current matrix of this view.
      */
-    Matrix getInverseMatrix() {
+    final Matrix getInverseMatrix() {
+        updateMatrix();
         if (mInverseMatrixDirty) {
             if (mInverseMatrix == null) {
                 mInverseMatrix = new Matrix();
@@ -5474,7 +5484,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      */
     public final void setTop(int top) {
         if (top != mTop) {
-            if (hasIdentityMatrix()) {
+            updateMatrix();
+            if (mMatrixIsIdentity) {
                 final ViewParent p = mParent;
                 if (p != null && mAttachInfo != null) {
                     final Rect r = mAttachInfo.mTmpInvalRect;
@@ -5523,7 +5534,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      */
     public final void setBottom(int bottom) {
         if (bottom != mBottom) {
-            if (hasIdentityMatrix()) {
+            updateMatrix();
+            if (mMatrixIsIdentity) {
                 final ViewParent p = mParent;
                 if (p != null && mAttachInfo != null) {
                     final Rect r = mAttachInfo.mTmpInvalRect;
@@ -5569,8 +5581,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      */
     public final void setLeft(int left) {
         if (left != mLeft) {
-            System.out.println("view " + this + " left = " + left);
-            if (hasIdentityMatrix()) {
+            updateMatrix();
+            if (mMatrixIsIdentity) {
                 final ViewParent p = mParent;
                 if (p != null && mAttachInfo != null) {
                     final Rect r = mAttachInfo.mTmpInvalRect;
@@ -5619,7 +5631,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      */
     public final void setRight(int right) {
         if (right != mRight) {
-            if (hasIdentityMatrix()) {
+            updateMatrix();
+            if (mMatrixIsIdentity) {
                 final ViewParent p = mParent;
                 if (p != null && mAttachInfo != null) {
                     final Rect r = mAttachInfo.mTmpInvalRect;
@@ -5758,13 +5771,13 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      * @param outRect The hit rectangle of the view.
      */
     public void getHitRect(Rect outRect) {
-        if (hasIdentityMatrix() || mAttachInfo == null) {
+        updateMatrix();
+        if (mMatrixIsIdentity || mAttachInfo == null) {
             outRect.set(mLeft, mTop, mRight, mBottom);
         } else {
-            Matrix m = getMatrix();
             final RectF tmpRect = mAttachInfo.mTmpTransformRect;
             tmpRect.set(-mPivotX, -mPivotY, getWidth() - mPivotX, getHeight() - mPivotY);
-            m.mapRect(tmpRect);
+            mMatrix.mapRect(tmpRect);
             outRect.set((int) tmpRect.left + mLeft, (int) tmpRect.top + mTop,
                     (int) tmpRect.right + mLeft, (int) tmpRect.bottom + mTop);
         }
@@ -5850,7 +5863,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      */
     public void offsetTopAndBottom(int offset) {
         if (offset != 0) {
-            if (hasIdentityMatrix()) {
+            updateMatrix();
+            if (mMatrixIsIdentity) {
                 final ViewParent p = mParent;
                 if (p != null && mAttachInfo != null) {
                     final Rect r = mAttachInfo.mTmpInvalRect;
@@ -5890,7 +5904,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, Accessibility
      */
     public void offsetLeftAndRight(int offset) {
         if (offset != 0) {
-            if (hasIdentityMatrix()) {
+            updateMatrix();
+            if (mMatrixIsIdentity) {
                 final ViewParent p = mParent;
                 if (p != null && mAttachInfo != null) {
                     final Rect r = mAttachInfo.mTmpInvalRect;