1 files changed, 96 insertions, 0 deletions
diff --git a/image/SkSurface_Base.h b/image/SkSurface_Base.h
new file mode 100644
index 00000000..6ea8d60b
--- /dev/null
+++ b/image/SkSurface_Base.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSurface_Base_DEFINED
+#define SkSurface_Base_DEFINED
+
+#include "SkSurface.h"
+#include "SkCanvas.h"
+
+class SkSurface_Base : public SkSurface {
+public:
+    SkSurface_Base(int width, int height);
+    virtual ~SkSurface_Base();
+
+    /**
+     *  Allocate a canvas that will draw into this surface. We will cache this
+     *  canvas, to return the same object to the caller multiple times. We
+     *  take ownership, and will call unref() on the canvas when we go out of
+     *  scope.
+     */
+    virtual SkCanvas* onNewCanvas() = 0;
+
+    virtual SkSurface* onNewSurface(const SkImage::Info&) = 0;
+
+    /**
+     *  Allocate an SkImage that represents the current contents of the surface.
+     *  This needs to be able to outlive the surface itself (if need be), and
+     *  must faithfully represent the current contents, even if the surface
+     *  is chaged after this calle (e.g. it is drawn to via its canvas).
+     */
+    virtual SkImage* onNewImageSnapshot() = 0;
+
+    /**
+     *  Default implementation:
+     *
+     *  image = this->newImageSnapshot();
+     *  if (image) {
+     *      image->draw(canvas, ...);
+     *      image->unref();
+     *  }
+     */
+    virtual void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*);
+
+    /**
+     *  If the surface is about to change, we call this so that our subclass
+     *  can optionally fork their backend (copy-on-write) in case it was
+     *  being shared with the cachedImage.
+     */
+    virtual void onCopyOnWrite(ContentChangeMode) = 0;
+
+    inline SkCanvas* getCachedCanvas();
+    inline SkImage* getCachedImage();
+
+    // called by SkSurface to compute a new genID
+    uint32_t newGenerationID();
+
+private:
+    SkCanvas*   fCachedCanvas;
+    SkImage*    fCachedImage;
+
+    void aboutToDraw(ContentChangeMode mode);
+    friend class SkCanvas;
+    friend class SkSurface;
+
+    inline void installIntoCanvasForDirtyNotification();
+
+    typedef SkSurface INHERITED;
+};
+
+SkCanvas* SkSurface_Base::getCachedCanvas() {
+    if (NULL == fCachedCanvas) {
+        fCachedCanvas = this->onNewCanvas();
+        this->installIntoCanvasForDirtyNotification();
+    }
+    return fCachedCanvas;
+}
+
+SkImage* SkSurface_Base::getCachedImage() {
+    if (NULL == fCachedImage) {
+        fCachedImage = this->onNewImageSnapshot();
+        this->installIntoCanvasForDirtyNotification();
+    }
+    return fCachedImage;
+}
+
+void SkSurface_Base::installIntoCanvasForDirtyNotification() {
+    if (NULL != fCachedCanvas) {
+        fCachedCanvas->setSurfaceBase(this);
+    }
+}
+
+#endif