Only recreate path textures when necessary

When a drawPath command is recorded in a display list, a copy of the
source path is made to preserve against possible modifications of the
said source path. Copies are discarded when a display list is cleared,
which usually happens on invalidate(). This means that even if a path
is never modified, the texture generated to draw it on screen is
destroyed every time an invalidate() is issued. This change fixes this
problem by introducing a reference to the source path in the copy.
If both the copy and the source path have the same genID, they are
the same path and can share the same texture.

Change-Id: I34849311c183e06336a1391d2d1568a087f973f6

3 files changed, 24 insertions, 13 deletions

diff --git a/libs/hwui/DisplayListRenderer.h b/libs/hwui/DisplayListRenderer.h
index 90a714526623..4a299c6eb47a 100644
--- a/libs/hwui/DisplayListRenderer.h
+++ b/libs/hwui/DisplayListRenderer.h
@@ -462,6 +462,7 @@ private:
         SkPath* pathCopy = mPathMap.valueFor(path);
         if (pathCopy == NULL || pathCopy->getGenerationID() != path->getGenerationID()) {
             pathCopy = new SkPath(*path);
+            pathCopy->setSourcePath(path);
             // replaceValueFor() performs an add if the entry doesn't exist
             mPathMap.replaceValueFor(path, pathCopy);
             mPaths.add(pathCopy);
diff --git a/libs/hwui/PathCache.cpp b/libs/hwui/PathCache.cpp
index e09c24381d9d..e363b73498df 100644
--- a/libs/hwui/PathCache.cpp
+++ b/libs/hwui/PathCache.cpp
@@ -83,6 +83,11 @@ void PathCache::clearGarbage() {
 }
 
 PathTexture* PathCache::get(SkPath* path, SkPaint* paint) {
+    const SkPath* sourcePath = path->getSourcePath();
+    if (sourcePath && sourcePath->getGenerationID() == path->getGenerationID()) {
+        path = const_cast<SkPath*>(sourcePath);
+    }
+
     PathCacheEntry entry(path, paint);
     PathTexture* texture = mCache.get(entry);
 
diff --git a/tests/HwAccelerationTest/src/com/android/test/hwui/PathsCacheActivity.java b/tests/HwAccelerationTest/src/com/android/test/hwui/PathsCacheActivity.java
index b8ad823bf73a..9ab2a860f7cc 100644
--- a/tests/HwAccelerationTest/src/com/android/test/hwui/PathsCacheActivity.java
+++ b/tests/HwAccelerationTest/src/com/android/test/hwui/PathsCacheActivity.java
@@ -92,19 +92,24 @@ public class PathsCacheActivity extends Activity {
 
             canvas.restore();
 
-//            Path path = makePath();
-//            int r = mRandom.nextInt(10);
-//            if (r == 5 || r == 3) {
-//                mPathList.add(path);
-//            } else if (r == 9) {
-//                mPathList.clear();
-//            }
-//
-//            canvas.save();
-//            canvas.translate(550.0f + mRandom.nextInt(50), 60.0f + mRandom.nextInt(50));
-//            canvas.drawPath(path, mMediumPaint);
-//            canvas.restore();
-//            
+            for (int i = 0; i < mRandom.nextInt(20); i++) {
+                Path path = makePath();
+                int r = mRandom.nextInt(10);
+                if (r == 5 || r == 3) {
+                    mPathList.add(path);
+                }
+    
+                canvas.save();
+                canvas.translate(450.0f + mRandom.nextInt(200), mRandom.nextInt(200));
+                canvas.drawPath(path, mMediumPaint);
+                canvas.restore();
+            }
+
+            int r = mRandom.nextInt(100);
+            if (r == 50) {
+                mPathList.clear();
+            }
+
             invalidate();
         }
     }