diff -r 000000000000 -r 6474c204b198 gfx/tests/gtest/TestRegion.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/tests/gtest/TestRegion.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,285 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "nsRegion.h"
+
+class TestLargestRegion {
+public:
+  static void TestSingleRect(nsRect r) {
+    nsRegion region(r);
+    EXPECT_TRUE(region.GetLargestRectangle().IsEqualInterior(r));
+  }
+  // Construct a rectangle, remove part of it, then check the remainder
+  static void TestNonRectangular() {
+    nsRegion r(nsRect(0, 0, 30, 30));
+
+    const int nTests = 19;
+    struct {
+      nsRect rect;
+      int64_t expectedArea;
+    } tests[nTests] = {
+      // Remove a 20x10 chunk from the square
+      { nsRect(0, 0, 20, 10), 600 },
+      { nsRect(10, 0, 20, 10), 600 },
+      { nsRect(10, 20, 20, 10), 600 },
+      { nsRect(0, 20, 20, 10), 600 },
+      // Remove a 10x20 chunk from the square
+      { nsRect(0, 0, 10, 20), 600 },
+      { nsRect(20, 0, 10, 20), 600 },
+      { nsRect(20, 10, 10, 20), 600 },
+      { nsRect(0, 10, 10, 20), 600 },
+      // Remove the center 10x10
+      { nsRect(10, 10, 10, 10), 300 },
+      // Remove the middle column
+      { nsRect(10, 0, 10, 30), 300 },
+      // Remove the middle row
+      { nsRect(0, 10, 30, 10), 300 },
+      // Remove the corners 10x10
+      { nsRect(0, 0, 10, 10), 600 },
+      { nsRect(20, 20, 10, 10), 600 },
+      { nsRect(20, 0, 10, 10), 600 },
+      { nsRect(0, 20, 10, 10), 600 },
+      // Remove the corners 20x20
+      { nsRect(0, 0, 20, 20), 300 },
+      { nsRect(10, 10, 20, 20), 300 },
+      { nsRect(10, 0, 20, 20), 300 },
+      { nsRect(0, 10, 20, 20), 300 }
+    };
+
+    for (int32_t i = 0; i < nTests; i++) {
+      nsRegion r2;
+      r2.Sub(r, tests[i].rect);
+
+      EXPECT_TRUE(r2.IsComplex()) << "nsRegion code got unexpectedly smarter!";
+
+      nsRect largest = r2.GetLargestRectangle();
+      EXPECT_TRUE(largest.width * largest.height == tests[i].expectedArea) <<
+        "Did not successfully find largest rectangle in non-rectangular region on iteration " << i;
+    }
+
+  }
+  static void TwoRectTest() {
+    nsRegion r(nsRect(0, 0, 100, 100));
+    const int nTests = 4;
+    struct {
+      nsRect rect1, rect2;
+      int64_t expectedArea;
+    } tests[nTests] = {
+      { nsRect(0, 0, 75, 40),  nsRect(0, 60, 75, 40),  2500 },
+      { nsRect(25, 0, 75, 40), nsRect(25, 60, 75, 40), 2500 },
+      { nsRect(25, 0, 75, 40), nsRect(0, 60, 75, 40),  2000 },
+      { nsRect(0, 0, 75, 40),  nsRect(25, 60, 75, 40), 2000 },
+    };
+    for (int32_t i = 0; i < nTests; i++) {
+      nsRegion r2;
+
+      r2.Sub(r, tests[i].rect1);
+      r2.Sub(r2, tests[i].rect2);
+
+      EXPECT_TRUE(r2.IsComplex()) << "nsRegion code got unexpectedly smarter!";
+
+      nsRect largest = r2.GetLargestRectangle();
+      EXPECT_TRUE(largest.width * largest.height == tests[i].expectedArea) <<
+        "Did not successfully find largest rectangle in two-rect-subtract region on iteration " << i;
+    }
+  }
+  static void TestContainsSpecifiedRect() {
+    nsRegion r(nsRect(0, 0, 100, 100));
+    r.Or(r, nsRect(0, 300, 50, 50));
+    EXPECT_TRUE(r.GetLargestRectangle(nsRect(0, 300, 10, 10)).IsEqualInterior(nsRect(0, 300, 50, 50))) <<
+      "Chose wrong rectangle";
+  }
+  static void TestContainsSpecifiedOverflowingRect() {
+    nsRegion r(nsRect(0, 0, 100, 100));
+    r.Or(r, nsRect(0, 300, 50, 50));
+    EXPECT_TRUE(r.GetLargestRectangle(nsRect(0, 290, 10, 20)).IsEqualInterior(nsRect(0, 300, 50, 50))) <<
+      "Chose wrong rectangle";
+  }
+};
+
+TEST(Gfx, RegionSingleRect) {
+  TestLargestRegion::TestSingleRect(nsRect(0, 52, 720, 480));
+  TestLargestRegion::TestSingleRect(nsRect(-20, 40, 50, 20));
+  TestLargestRegion::TestSingleRect(nsRect(-20, 40, 10, 8));
+  TestLargestRegion::TestSingleRect(nsRect(-20, -40, 10, 8));
+  TestLargestRegion::TestSingleRect(nsRect(-10, -10, 20, 20));
+}
+
+TEST(Gfx, RegionNonRectangular) {
+  TestLargestRegion::TestNonRectangular();
+}
+
+TEST(Gfx, RegionTwoRectTest) {
+  TestLargestRegion::TwoRectTest();
+}
+
+TEST(Gfx, RegionContainsSpecifiedRect) {
+  TestLargestRegion::TestContainsSpecifiedRect();
+}
+
+TEST(Gfx, RegionTestContainsSpecifiedOverflowingRect) {
+  TestLargestRegion::TestContainsSpecifiedOverflowingRect();
+}
+
+TEST(Gfx, RegionScaleToInside) {
+  { // no rectangles
+    nsRegion r;
+
+    nsIntRegion scaled = r.ScaleToInsidePixels(1, 1, 60);
+    nsIntRegion result;
+
+    EXPECT_TRUE(result.IsEqual(scaled)) <<
+      "scaled result incorrect";
+  }
+
+  { // one rectangle
+    nsRegion r(nsRect(0,44760,19096,264));
+
+    nsIntRegion scaled = r.ScaleToInsidePixels(1, 1, 60);
+    nsIntRegion result(nsIntRect(0,746,318,4));
+
+    EXPECT_TRUE(result.IsEqual(scaled)) <<
+      "scaled result incorrect";
+  }
+
+
+  { // the first rectangle gets adjusted
+    nsRegion r(nsRect(0,44760,19096,264));
+    r.Or(r, nsRect(0,45024,19360,1056));
+
+    nsIntRegion scaled = r.ScaleToInsidePixels(1, 1, 60);
+    nsIntRegion result(nsIntRect(0,746,318,5));
+    result.Or(result, nsIntRect(0,751,322,17));
+
+    EXPECT_TRUE(result.IsEqual(scaled)) <<
+      "scaled result incorrect";
+  }
+
+  { // the second rectangle gets adjusted
+    nsRegion r(nsRect(0,44760,19360,264));
+    r.Or(r, nsRect(0,45024,19096,1056));
+
+    nsIntRegion scaled = r.ScaleToInsidePixels(1, 1, 60);
+    nsIntRegion result(nsIntRect(0,746,322,4));
+    result.Or(result, nsIntRect(0,750,318,18));
+
+    EXPECT_TRUE(result.IsEqual(scaled)) <<
+      "scaled result incorrect";
+  }
+
+}
+
+TEST(Gfx, RegionSimplify) {
+  { // ensure simplify works on a single rect
+    nsRegion r(nsRect(0,100,200,100));
+
+    r.SimplifyOutwardByArea(100*100);
+
+    nsRegion result(nsRect(0,100,200,100));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not the same";
+  }
+
+  { // the rectangles will be merged
+    nsRegion r(nsRect(0,100,200,100));
+    r.Or(r, nsRect(0,200,300,200));
+
+    r.SimplifyOutwardByArea(100*100);
+
+    nsRegion result(nsRect(0,100,300,300));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not merged";
+  }
+
+  { // two rectangle on the first span
+    // one on the second
+    nsRegion r(nsRect(0,100,200,100));
+    r.Or(r, nsRect(0,200,300,200));
+    r.Or(r, nsRect(250,100,50,100));
+
+    EXPECT_TRUE(r.GetNumRects() == 3) <<
+      "wrong number of rects";
+
+    r.SimplifyOutwardByArea(100*100);
+
+    nsRegion result(nsRect(0,100,300,300));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not merged";
+  }
+
+  { // the rectangles will be merged
+    nsRegion r(nsRect(0,100,200,100));
+    r.Or(r, nsRect(0,200,300,200));
+    r.Or(r, nsRect(250,100,50,100));
+    r.Sub(r, nsRect(200,200,40,200));
+
+    EXPECT_TRUE(r.GetNumRects() == 4) <<
+      "wrong number of rects";
+
+    r.SimplifyOutwardByArea(100*100);
+
+    nsRegion result(nsRect(0,100,300,300));
+    result.Sub(result, nsRect(200,100,40,300));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not merged";
+  }
+
+  { // three spans of rectangles
+    nsRegion r(nsRect(0,100,200,100));
+    r.Or(r, nsRect(0,200,300,200));
+    r.Or(r, nsRect(250,100,50,50));
+    r.Sub(r, nsRect(200,200,40,200));
+
+    r.SimplifyOutwardByArea(100*100);
+
+    nsRegion result(nsRect(0,100,300,300));
+    result.Sub(result, nsRect(200,100,40,300));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not merged";
+  }
+
+  { // three spans of rectangles and an unmerged rectangle
+    nsRegion r(nsRect(0,100,200,100));
+    r.Or(r, nsRect(0,200,300,200));
+    r.Or(r, nsRect(250,100,50,50));
+    r.Sub(r, nsRect(200,200,40,200));
+    r.Or(r, nsRect(250,900,150,50));
+
+    r.SimplifyOutwardByArea(100*100);
+
+    nsRegion result(nsRect(0,100,300,300));
+    result.Sub(result, nsRect(200,100,40,300));
+    result.Or(result, nsRect(250,900,150,50));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not merged";
+  }
+
+  { // unmerged regions
+    nsRegion r(nsRect(0,100,200,100));
+    r.Or(r, nsRect(0,200,300,200));
+
+    r.SimplifyOutwardByArea(100);
+
+    nsRegion result(nsRect(0,100,200,100));
+    result.Or(result, nsRect(0,200,300,200));
+
+    EXPECT_TRUE(r.IsEqual(result)) <<
+      "regions not merged";
+  }
+
+  { // empty region
+    // just make sure this doesn't crash.
+    nsRegion r;
+    r.SimplifyOutwardByArea(100);
+  }
+
+}