switch GatherPixelRefs to use SkBaseDevice instead of SkBitmapDevice

src/utils/SkPictureUtils.cpp

Index: src/utils/SkPictureUtils.cpp
diff --git a/src/utils/SkPictureUtils.cpp b/src/utils/SkPictureUtils.cpp
index ffd9aa4429d24c307693b2b07fe465de8e78f5fb..506952c9ac4b73a9e7412258451fd5bff261d5ec 100644
--- a/src/utils/SkPictureUtils.cpp
+++ b/src/utils/SkPictureUtils.cpp
@@ -45,34 +45,38 @@ static void nothing_to_do() {}
 /**
  *  This device will route all bitmaps (primitives and in shaders) to its PRSet.
  *  It should never actually draw anything, so there need not be any pixels
- *  behind its device-bitmap.
- *  FIXME: Derive from SkBaseDevice.
+ *  behind its device.
  */
-class GatherPixelRefDevice : public SkBitmapDevice {
-private:
-    PixelRefSet*  fPRSet;
-
-    void addBitmap(const SkBitmap& bm) {
-        fPRSet->add(bm.pixelRef());
+class GatherPixelRefDevice : public SkBaseDevice {
+public:
+    GatherPixelRefDevice(int width, int height, PixelRefSet* prset) {
+        fSize.set(width, height);
+        fEmptyBitmap.setConfig(SkBitmap::kNo_Config, width, height);
+        fPRSet = prset;
     }
 
-    void addBitmapFromPaint(const SkPaint& paint) {
-        SkShader* shader = paint.getShader();
-        if (shader) {
-            SkBitmap bm;
-            // Check whether the shader is a gradient in order to short-circuit
-            // call to asABitmap to prevent generation of bitmaps from
-            // gradient shaders, which implement asABitmap.
-            if (SkShader::kNone_GradientType == shader->asAGradient(NULL) &&
-                shader->asABitmap(&bm, NULL, NULL)) {
-                fPRSet->add(bm.pixelRef());
-            }
-        }
+    virtual uint32_t getDeviceCapabilities() SK_OVERRIDE { return 0; }
+    virtual int width() const SK_OVERRIDE { return fSize.width(); }
+    virtual int height() const SK_OVERRIDE { return fSize.height(); }
+    virtual bool isOpaque() const SK_OVERRIDE { return false; }
+    virtual SkBitmap::Config config() const SK_OVERRIDE {
+        return SkBitmap::kNo_Config;
     }
-
-public:
-    GatherPixelRefDevice(const SkBitmap& bm, PixelRefSet* prset) : SkBitmapDevice(bm) {
-        fPRSet = prset;
+    virtual GrRenderTarget* accessRenderTarget() SK_OVERRIDE { return NULL; }
+    virtual bool filterTextFlags(const SkPaint& paint, TextFlags*) SK_OVERRIDE {
+        return true;
+    }
+    // TODO: allow this call to return failure, or move to SkBitmapDevice only.
+    virtual const SkBitmap& onAccessBitmap() SK_OVERRIDE {
+        return fEmptyBitmap;
+    }
+    virtual void lockPixels() SK_OVERRIDE { nothing_to_do(); }
+    virtual void unlockPixels() SK_OVERRIDE { nothing_to_do(); }
+    virtual bool allowImageFilter(SkImageFilter*) SK_OVERRIDE { return false; }
+    virtual bool canHandleImageFilter(SkImageFilter*) SK_OVERRIDE { return false; }
+    virtual bool filterImage(SkImageFilter*, const SkBitmap&, const SkMatrix&,
+                             SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
+        return false;
     }
 
     virtual void clear(SkColor color) SK_OVERRIDE {
@@ -156,8 +160,41 @@ protected:
         return false;
     }
 
+    virtual void replaceBitmapBackendForRasterSurface(const SkBitmap&) SK_OVERRIDE {
+        not_supported();
+    }
+    virtual SkBaseDevice* onCreateCompatibleDevice(SkBitmap::Config config,
+                                                   int width, int height,
+                                                   bool isOpaque,
+                                                   Usage usage) SK_OVERRIDE {
+        return SkNEW_ARGS(GatherPixelRefDevice, (width, height, fPRSet));

[scroggo, 2013/11/12 21:28:48]

Does this mean that if someone calls createCompatibleDevice the new device will
share the PixelRefSet? Is that intended?

[reed1, 2013/11/12 21:37:41]

I think we can assert that we only get called for savelayer, in which case I
think this is the correct behavior.

+    }
+    virtual void flush() SK_OVERRIDE {}
+
 private:
-    typedef SkBitmapDevice INHERITED;
+    PixelRefSet*  fPRSet;
+    SkBitmap fEmptyBitmap;  // legacy -- need to remove the need for this guy
+    SkISize fSize;
+
+    void addBitmap(const SkBitmap& bm) {
+      fPRSet->add(bm.pixelRef());
+    }
+
+    void addBitmapFromPaint(const SkPaint& paint) {
+      SkShader* shader = paint.getShader();
+      if (shader) {
+          SkBitmap bm;
+          // Check whether the shader is a gradient in order to short-circuit
+          // call to asABitmap to prevent generation of bitmaps from
+          // gradient shaders, which implement asABitmap.
+          if (SkShader::kNone_GradientType == shader->asAGradient(NULL) &&
+              shader->asABitmap(&bm, NULL, NULL)) {
+              fPRSet->add(bm.pixelRef());
+          }
+      }
+    }
+
+    typedef SkBaseDevice INHERITED;
 };
 
 class NoSaveLayerCanvas : public SkCanvas {
@@ -214,11 +251,7 @@ SkData* SkPictureUtils::GatherPixelRefs(SkPicture* pict, const SkRect& area) {
     SkTDArray<SkPixelRef*> array;
     PixelRefSet prset(&array);
 
-    SkBitmap emptyBitmap;
-    emptyBitmap.setConfig(SkBitmap::kARGB_8888_Config, pict->width(), pict->height());
-    // note: we do not set any pixels (shouldn't need to)
-
-    GatherPixelRefDevice device(emptyBitmap, &prset);
+    GatherPixelRefDevice device(pict->width(), pict->height(), &prset);
     NoSaveLayerCanvas canvas(&device);
 
     canvas.clipRect(area, SkRegion::kIntersect_Op, false);