add GM case nonclosedpaths. The 2 bugs below showed some non-closed paths which are easy to get wrong rendering results. So add a GM case for this kind paths to avoid potential bugs to be introduced.

BUG=skia:1782
BUG=skia:1811
R=bsalomon@google.com, caryclark@google.com, reed@google.com, robertphillips@google.com

Author: yunchao.he@intel.com

Review URL: https://codereview.chromium.org/64173009

git-svn-id: http://skia.googlecode.com/svn/trunk@12206 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 145 insertions, 0 deletions

diff --git a/gm/nonclosedpaths.cpp b/gm/nonclosedpaths.cpp
new file mode 100644
index 0000000000..bc37c54a83
--- /dev/null
+++ b/gm/nonclosedpaths.cpp
@@ -0,0 +1,145 @@
+/*
+ * Copyright 2013 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"
+#include "SkCanvas.h"
+#include "SkPath.h"
+
+namespace skiagm {
+
+// This GM tests a grab-bag of non-closed paths. All these paths look like
+// closed rects, but they don't call path.close(). Depending on the stroke
+// settings these slightly different paths give widely different results.
+class NonClosedPathsGM: public GM {
+public:
+    NonClosedPathsGM() {}
+
+    enum ClosureType {
+        TotallyNonClosed,  // The last point doesn't coincide with the first one in the contour.
+                           // The path looks not closed at all.
+
+        FakeCloseCorner,   // The last point coincides with the first one at a corner.
+                           // The path looks closed, but final rendering has 2 ends with cap.
+
+        FakeCloseMiddle,   // The last point coincides with the first one in the middle of a line.
+                           // The path looks closed, and the final rendering looks closed too.
+
+        kClosureTypeCount
+    };
+
+protected:
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("nonclosedpaths");
+    }
+
+    // 12 * 18 + 3 cases, every case is 100 * 100 pixels.
+    virtual SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(1220, 1920);
+    }
+
+    // Use rect-like geometry for non-closed path, for right angles make it
+    // easier to show the visual difference of lineCap and lineJoin.
+    static void MakePath(SkPath* path, ClosureType type) {
+        if (FakeCloseMiddle == type) {
+            path->moveTo(30, 50);
+            path->lineTo(30, 30);
+        } else {
+            path->moveTo(30, 30);
+        }
+        path->lineTo(70, 30);
+        path->lineTo(70, 70);
+        path->lineTo(30, 70);
+        path->lineTo(30, 50);
+        if (FakeCloseCorner == type) {
+            path->lineTo(30, 30);
+        }
+    }
+
+    // Set the location for the current test on the canvas
+    static void SetLocation(SkCanvas* canvas, int counter, int lineNum) {
+        SkScalar x = SK_Scalar1 * 100 * (counter % lineNum) + 10 + SK_Scalar1 / 4;
+        SkScalar y = SK_Scalar1 * 100 * (counter / lineNum) + 10 + 3 * SK_Scalar1 / 4;
+        canvas->translate(x, y);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        // Stroke widths are:
+        // 0(may use hairline rendering), 10(common case for stroke-style)
+        // 40 and 50(>= geometry width/height, make the contour filled in fact)
+        static const int kStrokeWidth[] = {0, 10, 40, 50};
+        size_t numWidths = SK_ARRAY_COUNT(kStrokeWidth);
+
+        static const SkPaint::Style kStyle[] = {
+            SkPaint::kStroke_Style, SkPaint::kStrokeAndFill_Style
+        };
+
+        static const SkPaint::Cap kCap[] = {
+            SkPaint::kButt_Cap, SkPaint::kRound_Cap, SkPaint::kSquare_Cap
+        };
+
+        static const SkPaint::Join kJoin[] = {
+            SkPaint::kMiter_Join, SkPaint::kRound_Join, SkPaint::kBevel_Join
+        };
+
+        static const ClosureType kType[] = {
+            TotallyNonClosed, FakeCloseCorner, FakeCloseMiddle
+        };
+
+        int counter = 0;
+        SkPaint paint;
+        paint.setAntiAlias(true);
+
+        // For stroke style painter and fill-and-stroke style painter
+        for (size_t type = 0; type < kClosureTypeCount; ++type) {
+            for (size_t style = 0; style < SK_ARRAY_COUNT(kStyle); ++style) {
+                for (size_t cap = 0; cap < SK_ARRAY_COUNT(kCap); ++cap) {
+                    for (size_t join = 0; join < SK_ARRAY_COUNT(kJoin); ++join) {
+                        for (size_t width = 0; width < numWidths; ++width) {
+                            canvas->save();
+                            SetLocation(canvas, counter, SkPaint::kJoinCount * numWidths);
+
+                            SkPath path;
+                            MakePath(&path, kType[type]);
+
+                            paint.setStyle(kStyle[style]);
+                            paint.setStrokeCap(kCap[cap]);
+                            paint.setStrokeJoin(kJoin[join]);
+                            paint.setStrokeWidth(SkIntToScalar(kStrokeWidth[width]));
+
+                            canvas->drawPath(path, paint);
+                            canvas->restore();
+                            ++counter;
+                        }
+                    }
+                }
+            }
+        }
+
+        // For fill style painter
+        paint.setStyle(SkPaint::kFill_Style);
+        for (size_t type = 0; type < kClosureTypeCount; ++type) {
+            canvas->save();
+            SetLocation(canvas, counter, SkPaint::kJoinCount * numWidths);
+
+            SkPath path;
+            MakePath(&path, kType[type]);
+
+            canvas->drawPath(path, paint);
+            canvas->restore();
+            ++counter;
+        }
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new NonClosedPathsGM;)
+
+}