Add repro GM for GPU clipped-AA vs. non-AA drawRect discrepancy

In the clip stack we were manually rounding out non-AA clip rects but leaving the hardening of non-AA drawRects up to the GPU. In some border cases the GPU can truncate rather than round out resulting in visual discrepancies.

BUG=423834

Committed: https://skia.googlesource.com/skia/+/933a03fecb65c83f81cf65d5cf9870c69aa379ff

Review URL: https://codereview.chromium.org/839883003

1 files changed, 92 insertions, 0 deletions

diff --git a/gm/clipdrawdraw.cpp b/gm/clipdrawdraw.cpp
new file mode 100644
index 0000000000..0e471dd148
--- /dev/null
+++ b/gm/clipdrawdraw.cpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+
+namespace skiagm {
+
+// This GM exercises the use case found in crbug.com/423834.
+// The following pattern:
+//    clipRect(r);
+//    drawRect(r, withAA);
+//    drawRect(r, noAA);
+// can leave 1 pixel wide remnants of the first rect.
+class ClipDrawDrawGM : public GM {
+public:
+    ClipDrawDrawGM() {
+        this->setBGColor(0xFFCCCCCC);
+    }
+
+protected:
+    SkString onShortName() SK_OVERRIDE {
+        return SkString("clipdrawdraw");
+    }
+
+    SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(512, 512);
+    }
+
+    // Vertical remnant
+    static void draw1(SkCanvas* canvas) {
+        SkPaint p;
+        p.setAntiAlias(true);
+
+        const SkRect rect = SkRect::MakeXYWH(8, 9, 404, 313);
+
+        canvas->save();
+
+        canvas->scale(0.5f, 0.5f);
+        canvas->translate(265, 265);
+
+        canvas->save();
+        canvas->clipRect(rect);
+        canvas->drawRect(rect, p);
+        canvas->restore();
+
+        p.setColor(SK_ColorWHITE);
+        p.setAntiAlias(false);
+        canvas->drawRect(rect, p);
+        canvas->restore();
+    }
+
+    // Horizontal remnant
+    static void draw2(SkCanvas* canvas) {
+        SkPaint p;
+        p.setAntiAlias(true);
+
+        const SkRect rect = SkRect::MakeXYWH(8, 9, 404, 313);
+
+        canvas->save();
+
+        canvas->translate(200.800003f, 172.299988f);
+        canvas->scale(0.8f, 0.8f);
+
+        canvas->save();
+        canvas->clipRect(rect);
+        canvas->drawRect(rect, p);
+        canvas->restore();
+
+        p.setColor(SK_ColorWHITE);
+        p.setAntiAlias(false);
+        canvas->drawRect(rect, p);
+        canvas->restore();
+    }
+
+    void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        draw1(canvas);
+        draw2(canvas);
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return SkNEW(ClipDrawDrawGM);)
+
+}