Culling API

*** SKP format breaking change ***

Adding a couple of culling primitives: pushCull(SkRect) & popCull().

These are currently only plumbed for SKP playback quickreject.

At record time, we perform a couple of optimizations to trim down the
number of redundant culls:

  * collapse empty pushCull/popCull pairs
  * skip pushCull/popCull pairs nested within an identical cull rect

Things still missing/to consider:

  * use an inlineable, simplified quickreject (Mike's old prototype)
  * debugger visualization for cull boxes
  * BBH integration: the initial prototype had some minimal BBH support,
    but since the optimizations required expensive rewinds and culling
    is expected to be a BBH alternative, it got dropped.

R=bsalomon@google.com, reed@google.com, robertphillips@google.com, caryclark@google.com, tomhudson@google.com, iancottrell@google.com

Author: fmalita@chromium.org

Review URL: https://codereview.chromium.org/138013009

git-svn-id: http://skia.googlecode.com/svn/trunk@13611 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/debugger/SkDrawCommand.cpp b/src/utils/debugger/SkDrawCommand.cpp
index 4e410d1..16b8556 100644
--- a/src/utils/debugger/SkDrawCommand.cpp
+++ b/src/utils/debugger/SkDrawCommand.cpp
@@ -65,6 +65,8 @@
         case COMMENT: return "Comment";
         case END_COMMENT_GROUP: return "EndCommentGroup";
         case DRAW_DRRECT: return "Draw DRRect";
+        case PUSH_CULL: return "PushCull";
+        case POP_CULL: return "PopCull";
         default:
             SkDebugf("DrawType error 0x%08x\n", type);
             SkASSERT(0);
@@ -936,3 +938,22 @@
 void SkTranslateCommand::execute(SkCanvas* canvas) {
     canvas->translate(fDx, fDy);
 }
+
+SkPushCullCommand::SkPushCullCommand(const SkRect& cullRect)
+    : fCullRect(cullRect) {
+    fDrawType = PUSH_CULL;
+    fInfo.push(SkObjectParser::RectToString(cullRect));
+}
+
+void SkPushCullCommand::execute(SkCanvas* canvas) {
+    //FIXME: add visualization overlay.
+    canvas->pushCull(fCullRect);
+}
+
+SkPopCullCommand::SkPopCullCommand() {
+    fDrawType = POP_CULL;
+}
+
+void SkPopCullCommand::execute(SkCanvas* canvas) {
+    canvas->popCull();
+}