Fixing backing store access in SkDeferredCanvas.

Chromium CL required for rolling skia DEPS past this change is posted here: https://chromiumcodereview.appspot.com/9341003/
 
BUG=http://code.google.com/p/skia/issues/detail?id=475
REVIEW=http://codereview.appspot.com/5626047/
TEST=DeferredCanvas unit test



git-svn-id: http://skia.googlecode.com/svn/trunk@3147 2bbb7eff-a529-9590-31e7-b0007b416f81

gyp/tests.gyp

@@ -27,6 +27,7 @@
         '../tests/ColorFilterTest.cpp',
         '../tests/ColorTest.cpp',
         '../tests/DataRefTest.cpp',
+        '../tests/DeferredCanvasTest.cpp',
         '../tests/DequeTest.cpp',
         '../tests/DrawBitmapRectTest.cpp',
         '../tests/DrawTextTest.cpp',

include/core/SkDevice.h

@@ -279,11 +279,14 @@ protected:
 
     ///////////////////////////////////////////////////////////////////////////
 
-    /** Update as needed the pixel value in the bitmap, so that the caller can access
-        the pixels directly. Note: only the pixels field should be altered. The config/width/height/rowbytes
-        must remain unchanged.
+    /** Update as needed the pixel value in the bitmap, so that the caller can
+        access the pixels directly. Note: only the pixels field should be
+        altered. The config/width/height/rowbytes must remain unchanged.
+        @param bitmap The device's bitmap
+        @return Echo the bitmap parameter, or an alternate (shadow) bitmap 
+            maintained by the subclass.
     */
-    virtual void onAccessBitmap(SkBitmap*);
+    virtual const SkBitmap& onAccessBitmap(SkBitmap*);
 
     SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
     // just for subclasses, to assign a custom pixelref

include/utils/SkDeferredCanvas.h

@@ -199,7 +199,7 @@ public:
                                  SkCanvas::Config8888 config8888) SK_OVERRIDE;
 
     protected:
-        virtual void onAccessBitmap(SkBitmap*) SK_OVERRIDE;
+        virtual const SkBitmap& onAccessBitmap(SkBitmap*) SK_OVERRIDE;
         virtual bool onReadPixels(const SkBitmap& bitmap,
                                   int x, int y,
                                   SkCanvas::Config8888 config8888) SK_OVERRIDE;
@@ -275,6 +275,7 @@ public:
         SkCanvas* fImmediateCanvas;
         SkCanvas* fRecordingCanvas;
         DeviceContext* fDeviceContext;
+        bool fBitmapInitialized;
     };
 
     DeferredDevice* getDeferredDevice() const;

src/core/SkDevice.cpp

@@ -77,11 +77,11 @@ void SkDevice::unlockPixels() {
 }
 
 const SkBitmap& SkDevice::accessBitmap(bool changePixels) {
-    this->onAccessBitmap(&fBitmap);
+    const SkBitmap& bitmap = this->onAccessBitmap(&fBitmap);
     if (changePixels) {
-        fBitmap.notifyPixelsChanged();
+        bitmap.notifyPixelsChanged();
     }
-    return fBitmap;
+    return bitmap;
 }
 
 void SkDevice::getGlobalBounds(SkIRect* bounds) const {
@@ -95,7 +95,7 @@ void SkDevice::clear(SkColor color) {
     fBitmap.eraseColor(color);
 }
 
-void SkDevice::onAccessBitmap(SkBitmap* bitmap) {}
+const SkBitmap& SkDevice::onAccessBitmap(SkBitmap* bitmap) {return *bitmap;}
 
 void SkDevice::setMatrixClip(const SkMatrix& matrix, const SkRegion& region,
                              const SkClipStack& clipStack) {

src/utils/SkDeferredCanvas.cpp

@@ -471,10 +471,10 @@ SkDeferredCanvas::DeferredDevice::DeferredDevice(
     SkSafeRef(fDeviceContext);
     fImmediateDevice = immediateDevice; // ref counted via fImmediateCanvas
     fImmediateCanvas = SkNEW_ARGS(SkCanvas, (fImmediateDevice));
-    SkSafeRef(fImmediateCanvas); 
     fRecordingCanvas = fPicture.beginRecording(fImmediateDevice->width(),
         fImmediateDevice->height(),
         SkPicture::kUsePathBoundsForClip_RecordingFlag);
+    fBitmapInitialized = false;
 }
 
 SkDeferredCanvas::DeferredDevice::~DeferredDevice()
@@ -593,10 +593,10 @@ void SkDeferredCanvas::DeferredDevice::writePixels(const SkBitmap& bitmap,
     flushIfNeeded(bitmap);
 }
 
-void SkDeferredCanvas::DeferredDevice::onAccessBitmap(SkBitmap* bitmap)
+const SkBitmap& SkDeferredCanvas::DeferredDevice::onAccessBitmap(SkBitmap*)
 {
-    SkASSERT(bitmap);
     flushPending();
+    return fImmediateDevice->accessBitmap(false);
 }
 
 SkDevice* SkDeferredCanvas::DeferredDevice::onCreateCompatibleDevice(

tests/DeferredCanvasTest.cpp

@@ -0,0 +1,59 @@
+
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "Test.h"
+#include "SkBitmap.h"
+#include "SkDeferredCanvas.h"
+
+
+static const int gWidth = 2;
+static const int gHeight = 2;
+
+static void create(SkBitmap* bm, SkBitmap::Config config, SkColor color) {
+    bm->setConfig(config, gWidth, gHeight);
+    bm->allocPixels();
+    bm->eraseColor(color);
+}
+
+static void TestDeferredCanvasBitmapAccess(skiatest::Reporter* reporter) {
+    SkBitmap store;
+
+    create(&store, SkBitmap::kARGB_8888_Config, 0xFFFFFFFF);
+    SkDevice device(store);
+    SkDeferredCanvas canvas(&device);
+
+    canvas.clear(0x00000000);
+
+    SkAutoLockPixels alp(store);
+    REPORTER_ASSERT(reporter, store.getColor(0,0) == 0xFFFFFFFF); //verify that clear was deferred
+    SkBitmap accessed = canvas.getDevice()->accessBitmap(false);
+    REPORTER_ASSERT(reporter, store.getColor(0,0) == 0x00000000); //verify that clear was executed
+    REPORTER_ASSERT(reporter, accessed.pixelRef() == store.pixelRef());
+}
+
+static void TestDeferredCanvasFlush(skiatest::Reporter* reporter) {
+    SkBitmap store;
+
+    create(&store, SkBitmap::kARGB_8888_Config, 0xFFFFFFFF);
+    SkDevice device(store);
+    SkDeferredCanvas canvas(&device);
+
+    canvas.clear(0x00000000);
+
+    SkAutoLockPixels alp(store);
+    REPORTER_ASSERT(reporter, store.getColor(0,0) == 0xFFFFFFFF); //verify that clear was deferred
+    canvas.flush();
+    REPORTER_ASSERT(reporter, store.getColor(0,0) == 0x00000000); //verify that clear was executed
+}
+
+static void TestDeferredCanvas(skiatest::Reporter* reporter) {
+    TestDeferredCanvasBitmapAccess(reporter);
+    TestDeferredCanvasFlush(reporter);
+}
+
+#include "TestClassDef.h"
+DEFINE_TESTCLASS("DeferredCanvas", TestDeferredCanvasClass, TestDeferredCanvas)