Add some comments to GrRectanizer_skyline

src/gpu/GrRectanizer_skyline.cpp

 
 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrRectanizer_skyline.h"
 #include "SkPoint.h"
@@ skipping 63 matching lines @@
 void GrRectanizerSkyline::addSkylineLevel(int skylineIndex, int x, int y, int width, int height) {
     SkylineSegment newSegment;
     newSegment.fX = x;
     newSegment.fY = y + height;
     newSegment.fWidth = width;
     fSkyline.insert(skylineIndex, 1, &newSegment);
 
     SkASSERT(newSegment.fX + newSegment.fWidth <= this->width());
     SkASSERT(newSegment.fY <= this->height());
 
-    // delete width of this skyline segment from following ones
+    // delete width of the new skyline segment from following ones
     for (int i = skylineIndex+1; i < fSkyline.count(); ++i) {
+        // The new segment subsumes all or part of fSkyline[i]
         SkASSERT(fSkyline[i-1].fX <= fSkyline[i].fX);
 
         if (fSkyline[i].fX < fSkyline[i-1].fX + fSkyline[i-1].fWidth) {
             int shrink = fSkyline[i-1].fX + fSkyline[i-1].fWidth - fSkyline[i].fX;
 
             fSkyline[i].fX += shrink;
             fSkyline[i].fWidth -= shrink;
 
             if (fSkyline[i].fWidth <= 0) {
+                // fully consumed
                 fSkyline.remove(i);
                 --i;
             } else {
+                // only partially consumed
                 break;
             }
         } else {
             break;
         }
     }
 
     // merge fSkylines
     for (int i = 0; i < fSkyline.count()-1; ++i) {
         if (fSkyline[i].fY == fSkyline[i+1].fY) {
             fSkyline[i].fWidth += fSkyline[i+1].fWidth;
             fSkyline.remove(i+1);
             --i;
         }
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrRectanizer* GrRectanizer::Factory(int width, int height) {
     return SkNEW_ARGS(GrRectanizerSkyline, (width, height));
 }