Invalidate path VBs when paths are destroyed

For this to work, we need access to the "original" path,
before any style was applied. To that end, add an original
path to GrShape (and unit tests of that functionality).

Then add a version of addGenIDChangeListener to GrShape,
that propagates to the original path, and use that in
tessellating path renderer.

Includes unit tests of caching behavior in the PR, all
of which failed without this change.

Bug: skia:
Change-Id: I98bb505f521e8ff07184f5c3fbd3c5fd1a22d3d5
Reviewed-on: https://skia-review.googlesource.com/50300
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

2 files changed, 124 insertions, 0 deletions

diff --git a/tests/GrShapeTest.cpp b/tests/GrShapeTest.cpp
index 087ac525c8..2b2a169477 100644
--- a/tests/GrShapeTest.cpp
+++ b/tests/GrShapeTest.cpp
@@ -17,6 +17,10 @@
 #include "SkSurface.h"
 #include "SkClipOpPriv.h"
 
+uint32_t GrShape::testingOnly_getOriginalGenerationID() const {
+    return fOriginalPath.getGenerationID();
+}
+
 using Key = SkTArray<uint32_t>;
 
 static bool make_key(Key* key, const GrShape& shape) {
@@ -493,6 +497,13 @@ private:
         make_key(&fAppliedPEThenStrokeKey, fAppliedPEThenStroke);
         make_key(&fAppliedFullKey, fAppliedFull);
 
+        // All shapes should report the same "original" path, so that path renderers can get to it
+        // if necessary.
+        uint32_t baseGenID = fBase.testingOnly_getOriginalGenerationID();
+        REPORTER_ASSERT(r, baseGenID == fAppliedPE.testingOnly_getOriginalGenerationID());
+        REPORTER_ASSERT(r, baseGenID == fAppliedPEThenStroke.testingOnly_getOriginalGenerationID());
+        REPORTER_ASSERT(r, baseGenID == fAppliedFull.testingOnly_getOriginalGenerationID());
+
         // Applying the path effect and then the stroke should always be the same as applying
         // both in one go.
         REPORTER_ASSERT(r, fAppliedPEThenStrokeKey == fAppliedFullKey);
diff --git a/tests/PathRendererCacheTests.cpp b/tests/PathRendererCacheTests.cpp
new file mode 100644
index 0000000000..da58fa4d7d
--- /dev/null
+++ b/tests/PathRendererCacheTests.cpp
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2017 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"
+
+#include "SkPath.h"
+
+#if SK_SUPPORT_GPU
+#include "GrClip.h"
+#include "GrContext.h"
+#include "GrContextPriv.h"
+#include "GrResourceCache.h"
+#include "effects/GrPorterDuffXferProcessor.h"
+#include "ops/GrTessellatingPathRenderer.h"
+
+static SkPath create_concave_path() {
+    SkPath path;
+    path.moveTo(100, 0);
+    path.lineTo(200, 200);
+    path.lineTo(100, 150);
+    path.lineTo(0, 200);
+    path.close();
+    return path;
+}
+
+static void draw_path(GrContext* ctx,
+                      GrRenderTargetContext* renderTargetContext,
+                      const SkPath& path,
+                      GrPathRenderer* pr,
+                      GrAAType aaType = GrAAType::kNone,
+                      GrStyle style = GrStyle(SkStrokeRec::kFill_InitStyle)) {
+    GrPaint paint;
+    paint.setXPFactory(GrPorterDuffXPFactory::Get(SkBlendMode::kSrc));
+
+    GrNoClip noClip;
+    SkIRect clipConservativeBounds = SkIRect::MakeWH(renderTargetContext->width(),
+                                                     renderTargetContext->height());
+    GrShape shape(path, style);
+    if (shape.style().applies()) {
+        shape = shape.applyStyle(GrStyle::Apply::kPathEffectAndStrokeRec, 1.0f);
+    }
+    SkMatrix matrix = SkMatrix::I();
+    GrPathRenderer::DrawPathArgs args{ctx,
+                                      std::move(paint),
+                                      &GrUserStencilSettings::kUnused,
+                                      renderTargetContext,
+                                      &noClip,
+                                      &clipConservativeBounds,
+                                      &matrix,
+                                      &shape,
+                                      aaType,
+                                      false};
+    pr->drawPath(args);
+}
+
+static void test_path(skiatest::Reporter* reporter,
+                      std::function<SkPath(void)> createPath,
+                      GrPathRenderer* pathRenderer,
+                      int expectedResources = 1,
+                      GrAAType aaType = GrAAType::kNone,
+                      GrStyle style = GrStyle(SkStrokeRec::kFill_InitStyle)) {
+    sk_sp<GrContext> ctx = GrContext::MakeMock(nullptr);
+    ctx->setResourceCacheLimits(100, 10000);
+    GrResourceCache* cache = ctx->getResourceCache();
+
+    sk_sp<GrRenderTargetContext> rtc(ctx->makeDeferredRenderTargetContext(
+            SkBackingFit::kApprox, 800, 800, kRGBA_8888_GrPixelConfig, nullptr, 0,
+            kTopLeft_GrSurfaceOrigin));
+    if (!rtc) {
+        return;
+    }
+
+    SkPath path = createPath();
+
+    // Initially, cache only has the render target context
+    REPORTER_ASSERT(reporter, 1 == cache->getResourceCount());
+
+    // Draw the path, check that new resource count matches expectations
+    draw_path(ctx.get(), rtc.get(), path, pathRenderer);
+    ctx->flush();
+    REPORTER_ASSERT(reporter, (1 + expectedResources) == cache->getResourceCount());
+
+    // Nothing should be purgeable yet
+    cache->purgeAsNeeded();
+    REPORTER_ASSERT(reporter, (1 + expectedResources) == cache->getResourceCount());
+
+    // Reset the path to change the GenID, which should invalidate any resources in the cache
+    path.reset();
+    cache->purgeAsNeeded();
+    REPORTER_ASSERT(reporter, 1 == cache->getResourceCount());
+}
+
+// Test that deleting the original path invalidates the VBs cached by the tessellating path renderer
+DEF_GPUTEST(TessellatingPathRendererCacheTest, reporter, factory) {
+    GrTessellatingPathRenderer tess;
+
+    // Tessellating path renderer stores vertex buffers in the cache (for non-AA paths)
+    test_path(reporter, create_concave_path, &tess);
+
+    // Test with a shape that applies. This needs to attach the invalidation logic to the original
+    // path, not the modified path produced by the style.
+    SkPaint paint;
+    paint.setStyle(SkPaint::kStroke_Style);
+    paint.setStrokeWidth(1);
+    GrStyle style(paint);
+    test_path(reporter, create_concave_path, &tess, 1, GrAAType::kNone, style);
+}
+
+#endif