Avoid re-rendering stencil clip for every draw with reducable clip stack

tests/ClipStackTest.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "Test.h"
 #if SK_SUPPORT_GPU
     #include "GrReducedClip.h"
@@ skipping 253 matching lines @@
 
             if (useRects) {
                 stack.clipDevRect(rectA, SkRegion::kIntersect_Op, false);
                 stack.clipDevRect(rectB, gOps[op], false);
             } else {
                 stack.clipDevPath(clipA, SkRegion::kIntersect_Op, false);
                 stack.clipDevPath(clipB, gOps[op], false);
             }
 
             REPORTER_ASSERT(reporter, !stack.isWideOpen());
+            REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID != stack.getTopmostGenID());
 
             stack.getConservativeBounds(0, 0, 100, 100, &devClipBound,
                                         &isIntersectionOfRects);
 
             if (useRects) {
                 REPORTER_ASSERT(reporter, isIntersectionOfRects ==
                         (gOps[op] == SkRegion::kIntersect_Op));
             } else {
                 REPORTER_ASSERT(reporter, !isIntersectionOfRects);
             }
 
             SkASSERT(testCase < gNumCases);
             REPORTER_ASSERT(reporter, devClipBound == gAnswerRectsBW[testCase]);
             ++testCase;
 
             stack.restore();
         }
     }
 }
 
 // Test out 'isWideOpen' entry point
 static void test_isWideOpen(skiatest::Reporter* reporter) {
+    {
+        // Empty stack is wide open. Wide open stack means that gen id is wide open.
+        SkClipStack stack;
+        REPORTER_ASSERT(reporter, stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID == stack.getTopmostGenID());
+    }
 
     SkRect rectA, rectB;
 
     rectA.iset(10, 10, 40, 40);
     rectB.iset(50, 50, 80, 80);
 
     // Stack should initially be wide open
     {
         SkClipStack stack;
 
         REPORTER_ASSERT(reporter, stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID == stack.getTopmostGenID());
     }
 
     // Test out case where the user specifies a union that includes everything
     {
         SkClipStack stack;
 
         SkPath clipA, clipB;
 
         clipA.addRoundRect(rectA, SkIntToScalar(5), SkIntToScalar(5));
         clipA.setFillType(SkPath::kInverseEvenOdd_FillType);
 
         clipB.addRoundRect(rectB, SkIntToScalar(5), SkIntToScalar(5));
         clipB.setFillType(SkPath::kInverseEvenOdd_FillType);
 
         stack.clipDevPath(clipA, SkRegion::kReplace_Op, false);
         stack.clipDevPath(clipB, SkRegion::kUnion_Op, false);
 
         REPORTER_ASSERT(reporter, stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID == stack.getTopmostGenID());
     }
 
     // Test out union w/ a wide open clip
     {
         SkClipStack stack;
 
         stack.clipDevRect(rectA, SkRegion::kUnion_Op, false);
 
         REPORTER_ASSERT(reporter, stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID == stack.getTopmostGenID());
     }
 
     // Test out empty difference from a wide open clip
     {
         SkClipStack stack;
 
         SkRect emptyRect;
         emptyRect.setEmpty();
 
         stack.clipDevRect(emptyRect, SkRegion::kDifference_Op, false);
 
         REPORTER_ASSERT(reporter, stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID == stack.getTopmostGenID());
     }
 
     // Test out return to wide open
     {
         SkClipStack stack;
 
         stack.save();
 
         stack.clipDevRect(rectA, SkRegion::kReplace_Op, false);
 
         REPORTER_ASSERT(reporter, !stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID != stack.getTopmostGenID());
 
         stack.restore();
 
         REPORTER_ASSERT(reporter, stack.isWideOpen());
+        REPORTER_ASSERT(reporter, SkClipStack::kWideOpenGenID == stack.getTopmostGenID());
     }
 }
 
 static int count(const SkClipStack& stack) {
 
     SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart);
 
     const SkClipStack::Element* element = NULL;
     int count = 0;
 
@@ skipping 572 matching lines @@
 
         GrReducedClip::InitialState initial;
         SkIRect tBounds(inflatedIBounds);
         SkIRect* tightBounds = r.nextBool() ? &tBounds : NULL;
         GrReducedClip::ReduceClipStack(stack,
                                        inflatedIBounds,
                                        &reducedClips,
                                        &initial,
                                        tightBounds);
 
+        REPORTER_ASSERT(reporter, reducedClips.count() == 0 ||
+                        reducedClips.tail()->getGenID() != SkClipStack::kInvalidGenID);
+
         // Build a new clip stack based on the reduced clip elements
         SkClipStack reducedStack;
         if (GrReducedClip::kAllOut_InitialState == initial) {
             // whether the result is bounded or not, the whole plane should start outside the clip.
             reducedStack.clipEmpty();
         }
         for (ElementList::Iter iter = reducedClips.headIter(); NULL != iter.get(); iter.next()) {
             add_elem_to_stack(*iter.get(), &reducedStack);
         }
 
@@ skipping 16 matching lines @@
         reducedRegion.setRect(inflatedIBounds);
         iter.reset(reducedStack, SkClipStack::Iter::kBottom_IterStart);
         while ((element = iter.next())) {
             add_elem_to_region(*element, inflatedIBounds, &reducedRegion);
         }
 
         REPORTER_ASSERT(reporter, region == reducedRegion);
     }
 }
 
+static void test_reduced_clip_stack_genid(skiatest::Reporter* reporter) {
+    SkClipStack stack;
+    stack.clipDevRect(SkRect::MakeXYWH(0, 0, 100, 100), SkRegion::kReplace_Op, true);
+    stack.clipDevRect(SkRect::MakeXYWH(0, 0, 50.3, 50.3), SkRegion::kReplace_Op, true);
+    SkIRect inflatedIBounds = SkIRect::MakeXYWH(0, 0, 100, 100);
+
+    GrReducedClip::ElementList reducedClips;
+    GrReducedClip::InitialState initial;
+    SkIRect tightBounds;
+
+    GrReducedClip::ReduceClipStack(stack,
+                                   inflatedIBounds,
+                                   &reducedClips,
+                                   &initial,
+                                   &tightBounds);
+
+    REPORTER_ASSERT(reporter, reducedClips.count() == 1);
+    // Clips will be cached based on the generation id. Make sure the gen id is valid.
+    REPORTER_ASSERT(reporter, SkClipStack::kInvalidGenID != reducedClips.head()->getGenID());
+
+}
+
+static void test_reduced_clip_stack_no_aa_crash(skiatest::Reporter* reporter) {
+    SkClipStack stack;
+    stack.clipDevRect(SkIRect::MakeXYWH(0, 0, 100, 100), SkRegion::kReplace_Op);
+    stack.clipDevRect(SkIRect::MakeXYWH(0, 0, 50, 50), SkRegion::kReplace_Op);
+    SkIRect inflatedIBounds = SkIRect::MakeXYWH(0, 0, 100, 100);
+
+    GrReducedClip::ElementList reducedClips;
+    GrReducedClip::InitialState initial;
+    SkIRect tightBounds;
+
+    // At the time, this would crash.
+    GrReducedClip::ReduceClipStack(stack,
+                                   inflatedIBounds,
+                                   &reducedClips,
+                                   &initial,
+                                   &tightBounds);
+
+    REPORTER_ASSERT(reporter, 0 == reducedClips.count());
+}
+
 #endif
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 static void TestClipStack(skiatest::Reporter* reporter) {
     SkClipStack stack;
 
     REPORTER_ASSERT(reporter, 0 == stack.getSaveCount());
     assert_count(reporter, stack, 0);
 
     static const SkIRect gRects[] = {
@@ skipping 28 matching lines @@
     test_bounds(reporter, true);        // once with rects
     test_bounds(reporter, false);       // once with paths
     test_isWideOpen(reporter);
     test_rect_merging(reporter);
     test_rect_replace(reporter);
     test_rect_inverse_fill(reporter);
     test_path_replace(reporter);
     test_quickContains(reporter);
 #if SK_SUPPORT_GPU
     test_reduced_clip_stack(reporter);
+    test_reduced_clip_stack_genid(reporter);
+    test_reduced_clip_stack_no_aa_crash(reporter);
 #endif
 }
 
 #include "TestClassDef.h"
 DEFINE_TESTCLASS("ClipStack", TestClipStackClass, TestClipStack)