Move canvas->surface association to the device subclasses

src/image/SkSurface_Raster.cpp

Index: src/image/SkSurface_Raster.cpp
diff --git a/src/image/SkSurface_Raster.cpp b/src/image/SkSurface_Raster.cpp
index 9c38640933926fdef9becf5221626faeba8e79ee..9b55c697a5e425fe1931706e5f0d72d2c9d90208 100644
--- a/src/image/SkSurface_Raster.cpp
+++ b/src/image/SkSurface_Raster.cpp
@@ -6,12 +6,14 @@
  */
 
 #include "SkSurface_Base.h"
-#include "SkImagePriv.h"
+#include "SkBitmapDevice.h"
 #include "SkCanvas.h"
-#include "SkDevice.h"
+#include "SkDeviceProperties.h"
+#include "SkImagePriv.h"
 #include "SkMallocPixelRef.h"
 
 static const size_t kIgnoreRowBytesValue = (size_t)~0;
+class SkRasterDevice;
 
 class SkSurface_Raster : public SkSurface_Base {
 public:
@@ -21,7 +23,7 @@ public:
                      void (*releaseProc)(void* pixels, void* context), void* context,
                      const SkSurfaceProps*);
     SkSurface_Raster(SkPixelRef*, const SkSurfaceProps*);
-
+    ~SkSurface_Raster();
     SkCanvas* onNewCanvas() SK_OVERRIDE;
     SkSurface* onNewSurface(const SkImageInfo&) SK_OVERRIDE;
     SkImage* onNewImageSnapshot(Budgeted) SK_OVERRIDE;
@@ -30,12 +32,102 @@ public:
     void onCopyOnWrite(ContentChangeMode) SK_OVERRIDE;
 
 private:
-    SkBitmap    fBitmap;
-    bool        fWeOwnThePixels;
+    SkRasterDevice* fDevice;
 
     typedef SkSurface_Base INHERITED;
 };
 
+/** A bitmap device that is used by SkSurface_Raster. */
+class SkRasterDevice : public SkBitmapDevice {
+public:
+    SkRasterDevice(const SkBitmap& bitmap);
+    enum Direct { kDirect };
+    SkRasterDevice(const SkBitmap& bitmap, Direct);
+    SkRasterDevice(const SkBitmap& bitmap, const SkDeviceProperties& props);
+    void setSurface(SkSurface_Raster* surface) { fSurface = surface; }
+
+    void discard() SK_OVERRIDE;
+    SkImage* newImageSnapshot(const SkSurfaceProps* props);
+
+    bool backendUsesPixelRef(const SkPixelRef* other) {
+        return this->getBackendBitmap().pixelRef() == other;
+    }
+
+    void discardOnWrite();
+    void copyOnWrite();
+private:
+    SkBaseDevice* onCreateCompatibleDevice(const CreateInfo& cinfo) SK_OVERRIDE;
+    const SkBitmap& onAccessBitmap() SK_OVERRIDE;
+    SkBitmap& getBackendBitmap() {
+        return fBitmap; // Note: accessing private SkBitmapDevice::fBitmap
+    }
+
+    bool fWeOwnThePixels;
+    SkSurface_Raster* fSurface;
+
+    typedef SkBitmapDevice INHERITED;
+};
+
+SkRasterDevice::SkRasterDevice(const SkBitmap& bitmap)
+    : INHERITED(bitmap)
+    , fWeOwnThePixels(true)
+    , fSurface(NULL) {
+}
+
+SkRasterDevice::SkRasterDevice(const SkBitmap& bitmap, Direct)
+    : INHERITED(bitmap)
+    , fWeOwnThePixels(false)
+    , fSurface(NULL) {
+
+}
+SkRasterDevice::SkRasterDevice(const SkBitmap& bitmap, const SkDeviceProperties& props)
+    : INHERITED(bitmap, props)
+    , fWeOwnThePixels(true)
+    , fSurface(NULL) {
+}
+
+SkBaseDevice* SkRasterDevice::onCreateCompatibleDevice(const CreateInfo& cinfo) {
+    SkDeviceProperties leaky(cinfo.fPixelGeometry);
+    SkBitmap bitmap;
+    if (!CreateBackendBitmap(cinfo.fInfo, &bitmap)) {
+        return NULL;
+    }
+    return SkNEW_ARGS(SkRasterDevice, (bitmap, leaky));
+}
+
+const SkBitmap& SkRasterDevice::onAccessBitmap() {
+    if (fSurface) {
+        fSurface->aboutToDraw(SkSurface::kRetain_ContentChangeMode);
+    }
+    return this->INHERITED::onAccessBitmap();
+}
+
+SkImage* SkRasterDevice::newImageSnapshot(const SkSurfaceProps* props) {
+    return SkNewImageFromBitmap(this->getBackendBitmap(), fWeOwnThePixels, props);
+}
+
+void SkRasterDevice::discard() {
+    if (fSurface) {
+        fSurface->aboutToDraw(SkSurface::kDiscard_ContentChangeMode);
+    }
+}
+
+void SkRasterDevice::discardOnWrite() {
+    SkASSERT(fWeOwnThePixels);
+    SkBitmap bitmap(this->getBackendBitmap());
+    bitmap.setPixelRef(NULL);
+    bitmap.allocPixels();
+    this->replaceBitmapBackend(bitmap);
+}
+
+void SkRasterDevice::copyOnWrite() {
+    SkASSERT(fWeOwnThePixels);
+    SkBitmap bitmap;
+    SkBitmap prev(this->getBackendBitmap());
+    prev.deepCopyTo(&bitmap);
+    this->replaceBitmapBackend(bitmap);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkSurface_Raster::Valid(const SkImageInfo& info, size_t rowBytes) {
@@ -85,10 +177,11 @@ bool SkSurface_Raster::Valid(const SkImageInfo& info, size_t rowBytes) {
 SkSurface_Raster::SkSurface_Raster(const SkImageInfo& info, void* pixels, size_t rb,
                                    void (*releaseProc)(void* pixels, void* context), void* context,
                                    const SkSurfaceProps* props)
-    : INHERITED(info, props)
-{
-    fBitmap.installPixels(info, pixels, rb, NULL, releaseProc, context);
-    fWeOwnThePixels = false;    // We are "Direct"
+    : INHERITED(info, props) {
+    SkBitmap bitmap;
+    bitmap.installPixels(info, pixels, rb, NULL, releaseProc, context);
+    fDevice = SkNEW_ARGS(SkRasterDevice, (bitmap, SkRasterDevice::kDirect));
+    fDevice->setSurface(this);
 }
 
 SkSurface_Raster::SkSurface_Raster(SkPixelRef* pr, const SkSurfaceProps* props)
@@ -96,17 +189,23 @@ SkSurface_Raster::SkSurface_Raster(SkPixelRef* pr, const SkSurfaceProps* props)
 {
     const SkImageInfo& info = pr->info();
 
-    fBitmap.setInfo(info, info.minRowBytes());
-    fBitmap.setPixelRef(pr);
-    fWeOwnThePixels = true;
-
+    SkBitmap bitmap;
+    bitmap.setInfo(info, info.minRowBytes());
+    bitmap.setPixelRef(pr);
     if (!info.isOpaque()) {
-        fBitmap.eraseColor(SK_ColorTRANSPARENT);
+        bitmap.eraseColor(SK_ColorTRANSPARENT);
     }
+    fDevice = SkNEW_ARGS(SkRasterDevice, (bitmap));
+    fDevice->setSurface(this);
+}
+
+SkSurface_Raster::~SkSurface_Raster() {
+    fDevice->setSurface(NULL);
+    SkSafeUnref(fDevice);
 }
 
 SkCanvas* SkSurface_Raster::onNewCanvas() {
-    return SkNEW_ARGS(SkCanvas, (fBitmap, this->props()));
+    return SkNEW_ARGS(SkCanvas, (fDevice, &this->props(), SkCanvas::kDefault_InitFlags));
 }
 
 SkSurface* SkSurface_Raster::onNewSurface(const SkImageInfo& info) {
@@ -115,30 +214,23 @@ SkSurface* SkSurface_Raster::onNewSurface(const SkImageInfo& info) {
 
 void SkSurface_Raster::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y,
                               const SkPaint* paint) {
-    canvas->drawBitmap(fBitmap, x, y, paint);
+    canvas->drawBitmap(fDevice->accessBitmap(false), x, y, paint);
 }
 
 SkImage* SkSurface_Raster::onNewImageSnapshot(Budgeted) {
-    return SkNewImageFromBitmap(fBitmap, fWeOwnThePixels, &this->props());
+    return fDevice->newImageSnapshot(&this->props());
 }
 
 void SkSurface_Raster::onCopyOnWrite(ContentChangeMode mode) {
-    // are we sharing pixelrefs with the image?
-    SkASSERT(this->getCachedImage(kNo_Budgeted));
-    if (SkBitmapImageGetPixelRef(this->getCachedImage(kNo_Budgeted)) == fBitmap.pixelRef()) {
-        SkASSERT(fWeOwnThePixels);
+    // Is the device sharing pixelrefs with the image?
+    SkImage* image = this->getCachedImage(kNo_Budgeted);
+    SkASSERT(image);
+    if (fDevice->backendUsesPixelRef(SkBitmapImageGetPixelRef(image))) {
         if (kDiscard_ContentChangeMode == mode) {
-            fBitmap.setPixelRef(NULL);
-            fBitmap.allocPixels();
+            fDevice->discardOnWrite();
         } else {
-            SkBitmap prev(fBitmap);
-            prev.deepCopyTo(&fBitmap);
+            fDevice->copyOnWrite();
         }
-        // Now fBitmap is a deep copy of itself (and therefore different from
-        // what is being used by the image. Next we update the canvas to use
-        // this as its backend, so we can't modify the image's pixels anymore.
-        SkASSERT(this->getCachedCanvas());
-        this->getCachedCanvas()->getDevice()->replaceBitmapBackendForRasterSurface(fBitmap);
     }
 }