From 9b3aa54bc9605257c701cf465813f5fb1d7ba39e Mon Sep 17 00:00:00 2001
From: reed <reed@google.com>
Date: Wed, 11 Mar 2015 08:47:12 -0700
Subject: [PATCH] optimization/fix: dirty the clip-bounds when we mod the clip
 in savelayer

Before the fix, we could use a stale cache of the clipbounds in quickReject. Often this could return false negatives, meaning we would try to draw more than we should (it would eventually be really clipped). Occasionally this could also report false positives (if the layer were outside of the normal canvas bounds, e.g. a layer with an offset imagefilter).

BUG=skia:
NOTREECHECKS=True

Review URL: https://codereview.chromium.org/983243003
---
 src/core/SkCanvas.cpp     |  4 +++-
 tests/QuickRejectTest.cpp | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index e4c03f3e5e..55b3b7ba7a 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -831,7 +831,7 @@ static bool bounds_affects_clip(SkCanvas::SaveFlags flags) {
 }
 
 bool SkCanvas::clipRectBounds(const SkRect* bounds, SaveFlags flags,
-                               SkIRect* intersection, const SkImageFilter* imageFilter) {
+                              SkIRect* intersection, const SkImageFilter* imageFilter) {
     SkIRect clipBounds;
     SkRegion::Op op = SkRegion::kIntersect_Op;
     if (!this->getClipDeviceBounds(&clipBounds)) {
@@ -854,6 +854,7 @@ bool SkCanvas::clipRectBounds(const SkRect* bounds, SaveFlags flags,
         // early exit if the layer's bounds are clipped out
         if (!ir.intersect(clipBounds)) {
             if (bounds_affects_clip(flags)) {
+                fCachedLocalClipBoundsDirty = true;
                 fMCRec->fRasterClip.setEmpty();
             }
             return false;
@@ -863,6 +864,7 @@ bool SkCanvas::clipRectBounds(const SkRect* bounds, SaveFlags flags,
     }
 
     if (bounds_affects_clip(flags)) {
+        fCachedLocalClipBoundsDirty = true;
         fClipStack->clipDevRect(ir, op);
         // early exit if the clip is now empty
         if (!fMCRec->fRasterClip.op(ir, op)) {
diff --git a/tests/QuickRejectTest.cpp b/tests/QuickRejectTest.cpp
index cefde12354..447d81615b 100644
--- a/tests/QuickRejectTest.cpp
+++ b/tests/QuickRejectTest.cpp
@@ -87,6 +87,23 @@ static void test_drawBitmap(skiatest::Reporter* reporter) {
     REPORTER_ASSERT(reporter, 0xFFFFFFFF == *dst.getAddr32(5, 5));
 }
 
+static void test_layers(skiatest::Reporter* reporter) {
+    SkCanvas canvas(100, 100);
+
+    SkRect r = SkRect::MakeWH(10, 10);
+    REPORTER_ASSERT(reporter, false == canvas.quickReject(r));
+
+    r.offset(300, 300);
+    REPORTER_ASSERT(reporter, true == canvas.quickReject(r));
+
+    // Test that saveLayer updates quickReject
+    SkRect bounds = SkRect::MakeLTRB(50, 50, 70, 70);
+    canvas.saveLayer(&bounds, NULL);
+    REPORTER_ASSERT(reporter, true == canvas.quickReject(SkRect::MakeWH(10, 10)));
+    REPORTER_ASSERT(reporter, false == canvas.quickReject(SkRect::MakeWH(60, 60)));
+}
+
 DEF_TEST(QuickReject, reporter) {
     test_drawBitmap(reporter);
+    test_layers(reporter);
 }