change gpudevice and pdfdevice to inherit from basedevice

include/core/SkDevice.h

 /*
  * Copyright 2010 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkDevice_DEFINED
 #define SkDevice_DEFINED
 
@@ skipping 86 matching lines @@
     */
     const SkBitmap& accessBitmap(bool changePixels);
 
     bool writePixels(const SkImageInfo&, const void*, size_t rowBytes, int x, int y);
 
     void* accessPixels(SkImageInfo* info, size_t* rowBytes);
 
     /**
      * Return the device's associated gpu render target, or NULL.
      */
-    virtual GrRenderTarget* accessRenderTarget() = 0;
+    virtual GrRenderTarget* accessRenderTarget() { return NULL; }
 
 
     /**
      *  Return the device's origin: its offset in device coordinates from
      *  the default origin in its canvas' matrix/clip
      */
     const SkIPoint& getOrigin() const { return fOrigin; }
 
     /**
      * onAttachToCanvas is invoked whenever a device is installed in a canvas
@@ skipping 32 matching lines @@
     struct TextFlags {
         uint32_t            fFlags;     // SkPaint::getFlags()
         SkPaint::Hinting    fHinting;
     };
 
     /**
      *  Device may filter the text flags for drawing text here. If it wants to
      *  make a change to the specified values, it should write them into the
      *  textflags parameter (output) and return true. If the paint is fine as
      *  is, then ignore the textflags parameter and return false.
-     *
-     *  The baseclass SkBaseDevice filters based on its depth and blitters.
      */
-    virtual bool filterTextFlags(const SkPaint& paint, TextFlags*) = 0;
+    virtual bool filterTextFlags(const SkPaint& paint, TextFlags*) { return false; }
 
     /**
      *
      *  DEPRECATED: This will be removed in a future change. Device subclasses
      *  should use the matrix and clip from the SkDraw passed to draw functions.
      *
      *  Called with the correct matrix and clip before this device is drawn
      *  to using those settings. If your subclass overrides this, be sure to
      *  call through to the base class as well.
      *
@@ skipping 92 matching lines @@
 
     /** Update as needed the pixel value in the bitmap, so that the caller can
         access the pixels directly.
         @return The device contents as a bitmap
     */
     virtual const SkBitmap& onAccessBitmap() = 0;
 
     /** Called when this device is installed into a Canvas. Balanced by a call
         to unlockPixels() when the device is removed from a Canvas.
     */
-    virtual void lockPixels() = 0;
-    virtual void unlockPixels() = 0;
+    virtual void lockPixels() {}
+    virtual void unlockPixels() {}
 
     /**
      *  Returns true if the device allows processing of this imagefilter. If
      *  false is returned, then the filter is ignored. This may happen for
      *  some subclasses that do not support pixel manipulations after drawing
      *  has occurred (e.g. printing). The default implementation returns true.
      */
-    virtual bool allowImageFilter(const SkImageFilter*) = 0;
+    virtual bool allowImageFilter(const SkImageFilter*) { return true; }
 
     /**
      *  Override and return true for filters that the device can handle
      *  intrinsically. Doing so means that SkCanvas will pass-through this
      *  filter to drawSprite and drawDevice (and potentially filterImage).
      *  Returning false means the SkCanvas will have apply the filter itself,
      *  and just pass the resulting image to the device.
      */
-    virtual bool canHandleImageFilter(const SkImageFilter*) = 0;
+    virtual bool canHandleImageFilter(const SkImageFilter*) { return false; }
 
     /**
      *  Related (but not required) to canHandleImageFilter, this method returns
      *  true if the device could apply the filter to the src bitmap and return
      *  the result (and updates offset as needed).
      *  If the device does not recognize or support this filter,
      *  it just returns false and leaves result and offset unchanged.
      */
     virtual bool filterImage(const SkImageFilter*, const SkBitmap&,
                              const SkImageFilter::Context& ctx,
-                             SkBitmap* result, SkIPoint* offset) = 0;
+                             SkBitmap* result, SkIPoint* offset) {
+        return false;
+    }
 
 protected:
     // default impl returns NULL
     virtual SkSurface* newSurface(const SkImageInfo&);
 
     // default impl returns NULL
     virtual const void* peekPixels(SkImageInfo*, size_t* rowBytes);
 
     /**
      *  The caller is responsible for "pre-clipping" the dst. The impl can assume that the dst
@@ skipping 57 matching lines @@
     friend class SkDeviceFilteredPaint;
     friend class SkDeviceImageFilterProxy;
     friend class SkDeferredDevice;    // for newSurface
 
     friend class SkSurface_Raster;
 
     // used to change the backend's pixels (and possibly config/rowbytes)
     // but cannot change the width/height, so there should be no change to
     // any clip information.
     // TODO: move to SkBitmapDevice
-    virtual void replaceBitmapBackendForRasterSurface(const SkBitmap&) = 0;
+    virtual void replaceBitmapBackendForRasterSurface(const SkBitmap&) {}
 
     // just called by SkCanvas when built as a layer
     void setOrigin(int x, int y) { fOrigin.set(x, y); }
     // just called by SkCanvas for saveLayer
     SkBaseDevice* createCompatibleDeviceForSaveLayer(const SkImageInfo&);
 
     virtual SkBaseDevice* onCreateDevice(const SkImageInfo&, Usage) {
         return NULL;
     }
 
     /** Causes any deferred drawing to the device to be completed.
      */
-    virtual void flush() = 0;
+    virtual void flush() {}
 
     SkIPoint    fOrigin;
     SkMetaData* fMetaData;
 
 #ifdef SK_DEBUG
     bool        fAttachedToCanvas;
 #endif
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif