Fix rendering artifact in edge fades.

Bug #4092053

The problem always existed but was made visible by partial invalidation.
When saving a layer, the renderer would try to postpone glClear()
operations until the next drawing command. This however does not work
since the clip might have changed. The fix is rather simple and
simply gets rid of this "optimization" (that turned out to be
usless anyway given how View issues saveLayer() calls.)

This change also fixes an issue with gradients (color stops where
not properly computed when using a null stops array) and optimizes
display lists rendering (quickly rejects larger portions of the
tree to avoid executing unnecessary code.)

Change-Id: I0f5b5f6e1220d41a09cc2fa84c212b0b4afd9c46

3 files changed, 40 insertions, 1 deletions

diff --git a/tests/HwAccelerationTest/res/drawable/gradient.xml b/tests/HwAccelerationTest/res/drawable/gradient.xml
new file mode 100644
index 0000000..756db0b
--- /dev/null
+++ b/tests/HwAccelerationTest/res/drawable/gradient.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2010 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <gradient
+        android:startColor="#FF707070"
+        android:endColor="#FF0C0C0C"
+        android:angle="270" />
+</shape>
diff --git a/tests/HwAccelerationTest/src/com/android/test/hwui/GradientsActivity.java b/tests/HwAccelerationTest/src/com/android/test/hwui/GradientsActivity.java
index f8422f4..90db818 100644
--- a/tests/HwAccelerationTest/src/com/android/test/hwui/GradientsActivity.java
+++ b/tests/HwAccelerationTest/src/com/android/test/hwui/GradientsActivity.java
@@ -193,6 +193,7 @@ public class GradientsActivity extends Activity {
         private final float mDrawWidth;
         private final float mDrawHeight;
         private final LinearGradient mGradient;
+        private final LinearGradient mGradientStops;
         private final Matrix mMatrix;
 
         ShadersView(Context c) {
@@ -202,6 +203,9 @@ public class GradientsActivity extends Activity {
             mDrawHeight = 200;
 
             mGradient = new LinearGradient(0, 0, 0, 1, 0xFF000000, 0, Shader.TileMode.CLAMP);
+            mGradientStops = new LinearGradient(0, 0, 0, 1,
+                    new int[] { 0xFFFF0000, 0xFF00FF00, 0xFF0000FF }, null, Shader.TileMode.CLAMP);
+
             mMatrix = new Matrix();
 
             mPaint = new Paint();
@@ -255,6 +259,19 @@ public class GradientsActivity extends Activity {
             mGradient.setLocalMatrix(mMatrix);
             canvas.drawRect(left, top, left + mDrawWidth, bottom, mPaint);
 
+            right = left + mDrawWidth;
+            left = 40.0f;
+            top = bottom + 20.0f;
+            bottom = top + 50.0f;
+
+            mPaint.setShader(mGradientStops);
+
+            mMatrix.setScale(1, mDrawWidth);
+            mMatrix.postRotate(90);
+            mMatrix.postTranslate(right, top);
+            mGradientStops.setLocalMatrix(mMatrix);
+            canvas.drawRect(left, top, right, bottom, mPaint);
+            
             canvas.restore();
         }
     }
diff --git a/tests/HwAccelerationTest/src/com/android/test/hwui/TransparentListActivity.java b/tests/HwAccelerationTest/src/com/android/test/hwui/TransparentListActivity.java
index 763169a..535f865 100644
--- a/tests/HwAccelerationTest/src/com/android/test/hwui/TransparentListActivity.java
+++ b/tests/HwAccelerationTest/src/com/android/test/hwui/TransparentListActivity.java
@@ -79,7 +79,7 @@ public class TransparentListActivity extends Activity {
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         
-        getWindow().setBackgroundDrawable(getResources().getDrawable(R.drawable.default_wallpaper));
+        getWindow().setBackgroundDrawable(getResources().getDrawable(R.drawable.gradient));
         setContentView(R.layout.list_activity);
 
         ListAdapter adapter = new SimpleListAdapter(this);