Scale to DIPs in ppb_graphics2d_impl for proper invalidation

webkit/plugins/ppapi/ppb_graphics_2d_impl_unittest.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/rect.h"
+#include "webkit/plugins/ppapi/ppb_graphics_2d_impl.h"
+
+TEST(PpapiGraphics2DImplTest, ScaleRectBounds) {
+  static const struct {
+    int x1;
+    int y1;
+    int w1;
+    int h1;
+    int x2;
+    int y2;
+    int w2;
+    int h2;
+    float scale;
+  } tests[] = {
+    { 0, 0, 0, 0, 0, 0, 0, 0, 1.0 },
+    { 0, 0, 0, 0, 0, 0, 0, 0, 2.0 },
+    { 0, 0, 4, 4, 0, 0, 2, 2, 0.5 },
+    { 1, 1, 4, 4, 0, 0, 3, 3, 0.5 },
+    { 53, 75, 100, 100, 53, 75, 100, 100, 1.0 },
+    { 53, 75, 100, 100, 106, 150, 200, 200, 2.0 },
+    { 53, 75, 100, 100, 26, 37, 51, 51, 0.5 },
+    { 53, 74, 100, 100, 26, 37, 51, 50, 0.5 },
+    { -1, -1, 100, 100, -1, -1, 51, 51, 0.5 },
+    { -2, -2, 100, 100, -1, -1, 50, 50, 0.5 },
+    { -101, -100, 50, 50, -51, -50, 26, 25, 0.5 }
+  };
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(tests); ++i) {
+    gfx::Rect orig(tests[i].x1, tests[i].y1, tests[i].w1, tests[i].h1);
+    gfx::Rect expected(tests[i].x2, tests[i].y2, tests[i].w2, tests[i].h2);
+    gfx::Rect scaled = webkit::ppapi::PPB_Graphics2D_Impl::ScaleRectBounds(
+        orig, tests[i].scale);
+    EXPECT_TRUE(scaled.Equals(expected));
+    // Reverse the scale and ensure all the original pixels are still inside
+    // the result.
+    gfx::Rect unscaled = webkit::ppapi::PPB_Graphics2D_Impl::ScaleRectBounds(
+        scaled, 1.0f / tests[i].scale);
+    EXPECT_TRUE(unscaled.Contains(orig));
+  }
+}