handle halfway case in scan converter

tests/DrawPathTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkDashPathEffect.h"
@@ skipping 199 matching lines @@
     path.moveTo(64, 3);
     path.cubicTo(-329936, -100000000, -329936, 100000000, 1153, 330003);
 
     SkPaint paint;
     paint.setAntiAlias(true);
 
     SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterN32Premul(640, 480));
     surface->getCanvas()->drawPath(path, paint);
 }
 
+// asserts if halfway case is not handled
+static void test_halfway() {
+    SkPaint paint;
+    SkPath path;
+    path.moveTo(16365.5f, 1394);
+    path.lineTo(16365.5f, 1387.5f);
+    path.quadTo(16365.5f, 1385.43f, 16367, 1383.96f);
+    path.quadTo(16368.4f, 1382.5f, 16370.5f, 1382.5f);
+    path.lineTo(16465.5f, 1382.5f);
+    path.quadTo(16467.6f, 1382.5f, 16469, 1383.96f);
+    path.quadTo(16470.5f, 1385.43f, 16470.5f, 1387.5f);
+    path.lineTo(16470.5f, 1394);
+    path.quadTo(16470.5f, 1396.07f, 16469, 1397.54f);
+    path.quadTo(16467.6f, 1399, 16465.5f, 1399);
+    path.lineTo(16370.5f, 1399);
+    path.quadTo(16368.4f, 1399, 16367, 1397.54f);
+    path.quadTo(16365.5f, 1396.07f, 16365.5f, 1394);
+    path.close();
+    SkPath p2;
+    SkMatrix m;
+    m.reset();
+    m.postTranslate(0.001f, 0.001f);
+    path.transform(m, &p2);
+
+    SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterN32Premul(640, 480));
+    SkCanvas* canvas = surface->getCanvas();
+    canvas->translate(-16366, -1383);
+    canvas->drawPath(p2, paint);
+
+    m.reset();
+    m.postTranslate(-0.001f, -0.001f);
+    path.transform(m, &p2);
+    canvas->drawPath(p2, paint);
+
+    m.reset();
+    path.transform(m, &p2);
+    canvas->drawPath(p2, paint);
+}
+
 // we used to assert if the bounds of the device (clip) was larger than 32K
 // even when the path itself was smaller. We just draw and hope in the debug
 // version to not assert.
 static void test_giantaa() {
     const int W = 400;
     const int H = 400;
     SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterN32Premul(33000, 10));
 
     SkPaint paint;
     paint.setAntiAlias(true);
@@ skipping 50 matching lines @@
     test_bigcubic();
     test_crbug_124652();
     test_crbug_140642();
     test_crbug_140803();
     test_inversepathwithclip();
     // why?
     if (false) test_crbug131181();
     test_infinite_dash(reporter);
     test_crbug_165432(reporter);
     test_big_aa_rect(reporter);
+    test_halfway();
 }