Fix rendering of drrects with small circular inner rrects.

Previously when the inner rrect was a circle with a radius of 1 we would
cause a inf * 0 in the shader which would lead to the shape not rendering.

This change also makes concentric circle drrects draw as stroked circles.

bug: chromium:789262

Change-Id: I6efbe3fdde25d6c4e031c7412d83df009afe014a
Reviewed-on: https://skia-review.googlesource.com/79141
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/gm/drrect_small_inner.cpp b/gm/drrect_small_inner.cpp
new file mode 100644
index 0000000000..1c7a7436ff
--- /dev/null
+++ b/gm/drrect_small_inner.cpp
@@ -0,0 +1,42 @@
+/*
+ * 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 "SkCanvas.h"
+#include "SkPaint.h"
+#include "SkRRect.h"
+#include "gm.h"
+
+DEF_SIMPLE_GM(drrect_small_inner, canvas, 170, 610) {
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    static constexpr SkScalar kOuterRadius = 35.f;
+    auto outer = SkRRect::MakeOval(SkRect::MakeXYWH(0, 0, 2 * kOuterRadius, 2 * kOuterRadius));
+    canvas->translate(10.f, 10.f);
+    canvas->save();
+    for (bool offcenter : {false, true}) {
+        for (bool oval : {false, true}) {
+            for (SkScalar innerRadiusX : {1.f, 0.5f, 0.1f, .01f}) {
+                SkScalar innerRadiusY = innerRadiusX;
+                if (oval) {
+                    innerRadiusY *= 0.95f;
+                }
+                SkScalar tx = kOuterRadius - innerRadiusX;
+                SkScalar ty = kOuterRadius - innerRadiusY;
+                if (offcenter) {
+                    tx += 1.f;
+                }
+                auto inner = SkRRect::MakeOval(
+                        SkRect::MakeXYWH(tx, ty, 2 * innerRadiusX, 2 * innerRadiusY));
+                canvas->drawDRRect(outer, inner, paint);
+                canvas->translate(0, 2 * kOuterRadius + 5);
+            }
+        }
+        canvas->restore();
+        canvas->translate(2 * kOuterRadius + 2, 0);
+    }
+    canvas->restore();
+}