michael@0: /*
michael@0:  * Copyright 2012 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkSurface_Base_DEFINED
michael@0: #define SkSurface_Base_DEFINED
michael@0: 
michael@0: #include "SkSurface.h"
michael@0: #include "SkCanvas.h"
michael@0: 
michael@0: class SkSurface_Base : public SkSurface {
michael@0: public:
michael@0:     SkSurface_Base(int width, int height);
michael@0:     explicit SkSurface_Base(const SkImageInfo&);
michael@0:     virtual ~SkSurface_Base();
michael@0: 
michael@0:     /**
michael@0:      *  Allocate a canvas that will draw into this surface. We will cache this
michael@0:      *  canvas, to return the same object to the caller multiple times. We
michael@0:      *  take ownership, and will call unref() on the canvas when we go out of
michael@0:      *  scope.
michael@0:      */
michael@0:     virtual SkCanvas* onNewCanvas() = 0;
michael@0: 
michael@0:     virtual SkSurface* onNewSurface(const SkImageInfo&) = 0;
michael@0: 
michael@0:     /**
michael@0:      *  Allocate an SkImage that represents the current contents of the surface.
michael@0:      *  This needs to be able to outlive the surface itself (if need be), and
michael@0:      *  must faithfully represent the current contents, even if the surface
michael@0:      *  is chaged after this calle (e.g. it is drawn to via its canvas).
michael@0:      */
michael@0:     virtual SkImage* onNewImageSnapshot() = 0;
michael@0: 
michael@0:     /**
michael@0:      *  Default implementation:
michael@0:      *
michael@0:      *  image = this->newImageSnapshot();
michael@0:      *  if (image) {
michael@0:      *      image->draw(canvas, ...);
michael@0:      *      image->unref();
michael@0:      *  }
michael@0:      */
michael@0:     virtual void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*);
michael@0: 
michael@0:     /**
michael@0:      *  If the surface is about to change, we call this so that our subclass
michael@0:      *  can optionally fork their backend (copy-on-write) in case it was
michael@0:      *  being shared with the cachedImage.
michael@0:      */
michael@0:     virtual void onCopyOnWrite(ContentChangeMode) = 0;
michael@0: 
michael@0:     inline SkCanvas* getCachedCanvas();
michael@0:     inline SkImage* getCachedImage();
michael@0: 
michael@0:     // called by SkSurface to compute a new genID
michael@0:     uint32_t newGenerationID();
michael@0: 
michael@0: private:
michael@0:     SkCanvas*   fCachedCanvas;
michael@0:     SkImage*    fCachedImage;
michael@0: 
michael@0:     void aboutToDraw(ContentChangeMode mode);
michael@0:     friend class SkCanvas;
michael@0:     friend class SkSurface;
michael@0: 
michael@0:     inline void installIntoCanvasForDirtyNotification();
michael@0: 
michael@0:     typedef SkSurface INHERITED;
michael@0: };
michael@0: 
michael@0: SkCanvas* SkSurface_Base::getCachedCanvas() {
michael@0:     if (NULL == fCachedCanvas) {
michael@0:         fCachedCanvas = this->onNewCanvas();
michael@0:         this->installIntoCanvasForDirtyNotification();
michael@0:     }
michael@0:     return fCachedCanvas;
michael@0: }
michael@0: 
michael@0: SkImage* SkSurface_Base::getCachedImage() {
michael@0:     if (NULL == fCachedImage) {
michael@0:         fCachedImage = this->onNewImageSnapshot();
michael@0:         this->installIntoCanvasForDirtyNotification();
michael@0:     }
michael@0:     return fCachedImage;
michael@0: }
michael@0: 
michael@0: void SkSurface_Base::installIntoCanvasForDirtyNotification() {
michael@0:     if (NULL != fCachedCanvas) {
michael@0:         fCachedCanvas->setSurfaceBase(this);
michael@0:     }
michael@0: }
michael@0: 
michael@0: #endif