New approach for GPU font atlas

src/gpu/GrAtlas.h

Index: src/gpu/GrAtlas.h
diff --git a/src/gpu/GrAtlas.h b/src/gpu/GrAtlas.h
index e290822fe1216c99859cb1b5cbbb1ddbe450dbbe..dbb2bb2ec0b27a7e068406eb7ef2cff88907dbaa 100644
--- a/src/gpu/GrAtlas.h
+++ b/src/gpu/GrAtlas.h
@@ -41,6 +41,8 @@ public:
     GrDrawTarget::DrawToken drawToken() const { return fDrawToken; }
     void setDrawToken(GrDrawTarget::DrawToken draw) { fDrawToken = draw; }
 
+    void resetRects();
+
 private:
     GrPlot();
     ~GrPlot(); // does not try to delete the fNext field
@@ -48,6 +50,7 @@ private:
     // for recycling
     GrDrawTarget::DrawToken fDrawToken;
 
+    GrPlot*                 fPrev;   // for the LRU list
     GrPlot*                 fNext;
 
     GrTexture*              fTexture;
@@ -68,19 +71,18 @@ public:
     // returns the containing GrPlot and location relative to the backing texture
     GrPlot* addToAtlas(GrAtlas*, int width, int height, const void*, GrIPoint16*);
 
-    // free up any plots that are not waiting on a draw call
-    bool removeUnusedPlots(GrAtlas* atlas);
+    // remove reference to this plot
+    bool removePlot(GrAtlas* atlas, const GrPlot* plot);
 
-    // to be called by ~GrAtlas()
-    void deletePlotList(GrPlot* plot);
+    // get a plot that only contains drawn content
+    GrPlot* getUnusedPlot();

[bsalomon, 2014/02/28 16:28:53]

This seems a little confusing to me. I read the comment several times to try to
understand what "unused" meant. 

What's the reason that we would want a plot that only contains rendered content?
Avoiding flushes?

[jvanverth1, 2014/02/28 19:55:27]

I've revised the comment -- I can't think of a better method name than this.

 
     GrTexture* getTexture() const {
         return fTexture;
     }
 
 private:
-    GrPlot* allocPlot();
-    void freePlot(GrPlot* plot);
+    void moveToHead(GrPlot* plot);
 
     GrGpu*        fGpu;
     GrPixelConfig fPixelConfig;
@@ -88,22 +90,23 @@ private:
 
     // allocated array of GrPlots
     GrPlot*       fPlots;
-    // linked list of free GrPlots
-    GrPlot*       fFreePlots;
+    // LRU list of GrPlots
+    GrPlot*       fHead;
+    GrPlot*       fTail;
 };
 
 class GrAtlas {
 public:
-    GrAtlas(GrAtlasMgr* mgr) : fPlots(NULL), fAtlasMgr(mgr) { }
-    ~GrAtlas() { fAtlasMgr->deletePlotList(fPlots); }
+    GrAtlas(GrAtlasMgr* mgr) : fAtlasMgr(mgr) { }
+    ~GrAtlas() { }
 
-    bool isEmpty() { return NULL == fPlots; }
+    bool isEmpty() { return 0 == fPlots.count(); }
 
     SkISize getSize() const;
 
 private:
-    GrPlot*     fPlots;
-    GrAtlasMgr* fAtlasMgr;
+    SkTDArray<GrPlot*> fPlots;
+    GrAtlasMgr*        fAtlasMgr;
 
     friend class GrAtlasMgr;
 };