Fixing how deferred canvas purges itself when a clear is recoreded.

This fixes performance because the old code was not reconstructing the clip
state correctly. This was causing a major performance degradation in the 
Galactic IE testdrive demo. This fix also enbles the purge
on clear optimization when there is saved state on the matrix/clip stack.
The approach taken to solve the problem consists in purging by running the
playback silently. The previous approach was tearing down and
restarting the gpipe, which required reconstructing state, which is fragile
and hard to do correctly, and has the side effect of clearing the bitmap heap
and the flattened dictionary.

Note: This CL is expected to slightly degrade performance of the 
deferred_canvas_record bench, which uses the skip on clear optimization.
This is because a silent playback takes more time that just destroying
the SkGPipe. Correctness trumps performance.

BUG=http://code.google.com/p/chromium/issues/detail?id=146178
Review URL: https://codereview.appspot.com/6531048

git-svn-id: http://skia.googlecode.com/svn/trunk@5627 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 22 insertions, 62 deletions

diff --git a/src/utils/SkDeferredCanvas.cpp b/src/utils/SkDeferredCanvas.cpp
index a3306c52a3..5beaa5bc92 100644
--- a/src/utils/SkDeferredCanvas.cpp
+++ b/src/utils/SkDeferredCanvas.cpp
@@ -21,6 +21,11 @@ enum {
     kDefaultMaxRecordingStorageBytes = 64*1024*1024,
 };
 
+enum PlaybackMode {
+    kNormal_PlaybackMode,
+    kSilent_PlaybackMode,
+};
+
 namespace {
 bool shouldDrawImmediately(const SkBitmap* bitmap, const SkPaint* paint) {
     if (bitmap && bitmap->getTexture() && !bitmap->isImmutable()) {
@@ -152,7 +157,6 @@ public:
     virtual void* requestBlock(size_t minRequest, size_t* actual) SK_OVERRIDE;
     virtual void notifyWritten(size_t bytes) SK_OVERRIDE;
     void playback(bool silent);
-    void reset();
     bool hasRecorded() const { return fAllocator.blockCount() != 0; }
     size_t storageAllocatedForRecording() const { return fAllocator.totalCapacity(); }
 private:
@@ -219,16 +223,9 @@ void DeferredPipeController::playback(bool silent) {
     fAllocator.reset();
 }
 
-void DeferredPipeController::reset() {
-    fBlockList.reset();
-    fBlock = NULL;
-    fAllocator.reset();
-}
-
 //-----------------------------------------------------------------------------
 // DeferredDevice
 //-----------------------------------------------------------------------------
-
 class DeferredDevice : public SkDevice {
 public:
     DeferredDevice(SkDevice* immediateDevice,
@@ -242,7 +239,7 @@ public:
     bool isFreshFrame();
     size_t storageAllocatedForRecording() const;
     size_t freeMemoryIfPossible(size_t bytesToFree);
-    void flushPendingCommands(bool silent);
+    void flushPendingCommands(PlaybackMode);
     void skipPendingCommands();
     void setMaxRecordingStorage(size_t);
     void recordedDrawCommand();
@@ -329,7 +326,6 @@ protected:
 private:
     virtual void flush();
 
-    void endRecording();
     void beginRecording();
 
     DeferredPipeController fPipeController;
@@ -360,7 +356,7 @@ DeferredDevice::DeferredDevice(
 }
 
 DeferredDevice::~DeferredDevice() {
-    this->flushPendingCommands(true);
+    this->flushPendingCommands(kSilent_PlaybackMode);
     SkSafeUnref(fImmediateCanvas);
 }
 
@@ -369,12 +365,6 @@ void DeferredDevice::setMaxRecordingStorage(size_t maxStorage) {
     this->recordingCanvas(); // Accessing the recording canvas applies the new limit.
 }
 
-void DeferredDevice::endRecording() {
-    fPipeWriter.endRecording();
-    fPipeController.reset();
-    fRecordingCanvas = NULL;
-}
-
 void DeferredDevice::beginRecording() {
     SkASSERT(NULL == fRecordingCanvas);
     fRecordingCanvas = fPipeWriter.startRecording(&fPipeController, 0,
@@ -387,39 +377,9 @@ void DeferredDevice::setNotificationClient(
 }
 
 void DeferredDevice::skipPendingCommands() {
-    if (!fRecordingCanvas->isDrawingToLayer()) {
+    if (!fRecordingCanvas->isDrawingToLayer() && fPipeController.hasRecorded()) {
         fFreshFrame = true;
-
-        // TODO: find a way to transfer the state stack and layers
-        // to the new recording canvas.  For now, purging only works
-        // with an empty stack.  A save count of 1 means an empty stack.
-        SkASSERT(fRecordingCanvas->getSaveCount() >= 1);
-        if (fRecordingCanvas->getSaveCount() == 1) {
-
-            // Save state that is trashed by the purge
-            SkDrawFilter* drawFilter = fRecordingCanvas->getDrawFilter();
-            SkSafeRef(drawFilter); // So that it survives the purge
-            SkMatrix matrix = fRecordingCanvas->getTotalMatrix();
-            SkRegion clipRegion = fRecordingCanvas->getTotalClip();
-
-            // beginRecording creates a new recording canvas and discards the
-            // old one, hence purging deferred draw ops.
-            this->endRecording();
-            this->beginRecording();
-            fPreviousStorageAllocated = storageAllocatedForRecording();
-
-            // Restore pre-purge state
-            if (!clipRegion.isEmpty()) {
-                fRecordingCanvas->clipRegion(clipRegion,
-                    SkRegion::kReplace_Op);
-            }
-            if (!matrix.isIdentity()) {
-                fRecordingCanvas->setMatrix(matrix);
-            }
-            if (drawFilter) {
-                fRecordingCanvas->setDrawFilter(drawFilter)->unref();
-            }
-        }
+        flushPendingCommands(kSilent_PlaybackMode);
     }
 }
 
@@ -429,23 +389,23 @@ bool DeferredDevice::isFreshFrame() {
     return ret;
 }
 
-void DeferredDevice::flushPendingCommands(bool silent) {
+void DeferredDevice::flushPendingCommands(PlaybackMode playbackMode) {
     if (!fPipeController.hasRecorded()) {
         return;
     }
-    if (fNotificationClient) {
+    if (playbackMode == kNormal_PlaybackMode && fNotificationClient) {
         fNotificationClient->prepareForDraw();
     }
     fPipeWriter.flushRecording(true);
-    fPipeController.playback(silent);
-    if (fNotificationClient) {
+    fPipeController.playback(playbackMode);
+    if (playbackMode == kNormal_PlaybackMode && fNotificationClient) {
         fNotificationClient->flushedDrawCommands();
     }
     fPreviousStorageAllocated = storageAllocatedForRecording();
 }
 
 void DeferredDevice::flush() {
-    this->flushPendingCommands(false);
+    this->flushPendingCommands(kNormal_PlaybackMode);
     fImmediateCanvas->flush();
 }
 
@@ -468,7 +428,7 @@ void DeferredDevice::recordedDrawCommand() {
         size_t tryFree = storageAllocated - fMaxRecordingStorageBytes;
         if (this->freeMemoryIfPossible(tryFree) < tryFree) {
             // Flush is necessary to free more space.
-            this->flushPendingCommands(false);
+            this->flushPendingCommands(kNormal_PlaybackMode);
             // Free as much as possible to avoid oscillating around fMaxRecordingStorageBytes
             // which could cause a high flushing frequency.
             this->freeMemoryIfPossible(~0U);
@@ -500,7 +460,7 @@ int DeferredDevice::height() const {
 }
 
 SkGpuRenderTarget* DeferredDevice::accessRenderTarget() {
-    this->flushPendingCommands(false);
+    this->flushPendingCommands(kNormal_PlaybackMode);
     return fImmediateDevice->accessRenderTarget();
 }
 
@@ -516,7 +476,7 @@ void DeferredDevice::writePixels(const SkBitmap& bitmap,
         SkCanvas::kNative_Premul_Config8888 != config8888 &&
         kPMColorAlias != config8888) {
         //Special case config: no deferral
-        this->flushPendingCommands(false);
+        this->flushPendingCommands(kNormal_PlaybackMode);
         fImmediateDevice->writePixels(bitmap, x, y, config8888);
         return;
     }
@@ -524,7 +484,7 @@ void DeferredDevice::writePixels(const SkBitmap& bitmap,
     SkPaint paint;
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
     if (shouldDrawImmediately(&bitmap, NULL)) {
-        this->flushPendingCommands(false);
+        this->flushPendingCommands(kNormal_PlaybackMode);
         fImmediateCanvas->drawSprite(bitmap, x, y, &paint);
     } else {
         this->recordingCanvas()->drawSprite(bitmap, x, y, &paint);
@@ -534,7 +494,7 @@ void DeferredDevice::writePixels(const SkBitmap& bitmap,
 }
 
 const SkBitmap& DeferredDevice::onAccessBitmap(SkBitmap*) {
-    this->flushPendingCommands(false);
+    this->flushPendingCommands(kNormal_PlaybackMode);
     return fImmediateDevice->accessBitmap(false);
 }
 
@@ -553,7 +513,7 @@ SkDevice* DeferredDevice::onCreateCompatibleDevice(
 
 bool DeferredDevice::onReadPixels(
     const SkBitmap& bitmap, int x, int y, SkCanvas::Config8888 config8888) {
-    this->flushPendingCommands(false);
+    this->flushPendingCommands(kNormal_PlaybackMode);
     return fImmediateCanvas->readPixels(const_cast<SkBitmap*>(&bitmap),
                                                    x, y, config8888);
 }
@@ -615,7 +575,7 @@ void SkDeferredCanvas::setDeferredDrawing(bool val) {
     if (val != fDeferredDrawing) {
         if (fDeferredDrawing) {
             // Going live.
-            this->getDeferredDevice()->flushPendingCommands(false);
+            this->getDeferredDevice()->flushPendingCommands(kNormal_PlaybackMode);
         }
         fDeferredDrawing = val;
     }
@@ -631,7 +591,7 @@ bool SkDeferredCanvas::isFreshFrame() const {
 
 void SkDeferredCanvas::silentFlush() {
     if (fDeferredDrawing) {
-        this->getDeferredDevice()->flushPendingCommands(true);
+        this->getDeferredDevice()->flushPendingCommands(kSilent_PlaybackMode);
     }
 }