Proposed SkCanvas API for preLoading textures to VRAM v2.0

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
@@ skipping 160 matching lines @@
      * possibly from SkCanvas' dtor.
      */
     virtual void onDetachFromCanvas() {
         SkASSERT(fAttachedToCanvas);
         this->unlockPixels();
 #ifdef SK_DEBUG
         fAttachedToCanvas = false;
 #endif
     };
 
+    /**

[reed1, 2014/03/13 18:33:55]

Not sure I follow why we have two of these.
- does optimize() always create something, even if I call it twice?
- does optimizedRender() return true if optimize() was called? If so, is that
valuable to the client?

[robertphillips, 2014/03/13 19:58:28]

There are two possible landing points for this. In one, the client calls
optimize once (and optimization data is collected for the whole picture)  and
then calls optimizedRender several times (rendering portions of the picture). In
the other, the client calls optimize for each sub-portion and then only calls
optimizedRender when they want pixels for that sub-portion. In the former,
multiple calls to optimize() would return the same information. In the latter,
the different calls would return different data. 

optimizedRender returns true if there is nothing for SkCanvas::drawPicture to
do. Initially, when we are just preloading textures, we will still want
SkCanvas::drawPicture to loop over the operations and draw them. Later, when we
have enough information to just render the entire scene, we will want SkCanvas
to just return. 

I believe Chromium will, at least initially, want to separately control
information collection and rendering. If we land in the second world (where
optimizations are only determined for a sub-region), I suspect Chromium will
want even more control over when analysis is performed (and when they can purge
the collected information).

+     *  PRIVATE / EXPERIMENTAL -- do not call
+     *  Construct an acceleration object and attach it to 'picture'
+     */
+    virtual void EXPERIMENTAL_optimize(SkPicture* picture);
+
+    /**
+     *  PRIVATE / EXPERIMENTAL -- do not call
+     *  Possibly use the results of an earlier 'optimize' call to render 'picture'.
+     *  Return true if all rendering has been done; false if the caller
+     *  (i.e., SkCanvas) should render normally.
+     */
+    virtual bool EXPERIMENTAL_optimizedRender(const SkPicture& picture);
+
 protected:
     enum Usage {
        kGeneral_Usage,
        kSaveLayer_Usage  // <! internal use only
     };
 
     struct TextFlags {
         uint32_t            fFlags;     // SkPaint::getFlags()
         SkPaint::Hinting    fHinting;
     };
@@ skipping 262 matching lines @@
     SkMetaData* fMetaData;
 
 #ifdef SK_DEBUG
     bool        fAttachedToCanvas;
 #endif
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif