ui: Fix NinePatchPainter to work in physical pixels.

ui/gfx/nine_image_painter_unittest.cc

 // Copyright 2015 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 "ui/gfx/nine_image_painter.h"
 
+#include "base/base64.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace gfx {
 
+static std::string GetPNGDataUrl(const SkBitmap& bitmap) {
+  std::vector<unsigned char> png_data;
+  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap, false, &png_data);
+  std::string data_url;
+  data_url.insert(data_url.end(), png_data.begin(), png_data.end());
+  base::Base64Encode(data_url, &data_url);
+  data_url.insert(0, "data:image/png;base64,");
+
+  return data_url;
+}
+
 TEST(NineImagePainterTest, GetSubsetRegions) {
   SkBitmap src;
   src.allocN32Pixels(40, 50);
   const ImageSkia image_skia(ImageSkiaRep(src, 1.0));
   const Insets insets(1, 2, 3, 4);
   std::vector<Rect> rects;
   NineImagePainter::GetSubsetRegions(image_skia, insets, &rects);
   ASSERT_EQ(9u, rects.size());
   EXPECT_EQ(gfx::Rect(0, 0, 2, 1), rects[0]);
   EXPECT_EQ(gfx::Rect(2, 0, 34, 1), rects[1]);
   EXPECT_EQ(gfx::Rect(36, 0, 4, 1), rects[2]);
   EXPECT_EQ(gfx::Rect(0, 1, 2, 46), rects[3]);
   EXPECT_EQ(gfx::Rect(2, 1, 34, 46), rects[4]);
   EXPECT_EQ(gfx::Rect(36, 1, 4, 46), rects[5]);
   EXPECT_EQ(gfx::Rect(0, 47, 2, 3), rects[6]);
   EXPECT_EQ(gfx::Rect(2, 47, 34, 3), rects[7]);
   EXPECT_EQ(gfx::Rect(36, 47, 4, 3), rects[8]);
 }
 
-TEST(NineImagePainterTest, PaintScale) {
+TEST(NineImagePainterTest, PaintHighDPI) {
   SkBitmap src;
   src.allocN32Pixels(100, 100);
   src.eraseColor(SK_ColorRED);
   src.eraseArea(SkIRect::MakeXYWH(10, 10, 80, 80), SK_ColorGREEN);
 
-  gfx::ImageSkia image(gfx::ImageSkiaRep(src, 0.0f));
+  float image_scale = 2.f;
+
+  gfx::ImageSkia image(gfx::ImageSkiaRep(src, image_scale));
   gfx::Insets insets(10, 10, 10, 10);
   gfx::NineImagePainter painter(image, insets);
 
-  int image_scale = 2;
   bool is_opaque = true;
-  gfx::Canvas canvas(gfx::Size(400, 400), image_scale, is_opaque);
-  canvas.Scale(2, 1);
+  gfx::Canvas canvas(gfx::Size(100, 100), image_scale, is_opaque);
+  canvas.Translate(gfx::Vector2d(20, 10));
 
-  gfx::Rect bounds(0, 0, 100, 100);
+  gfx::Rect bounds(0, 0, 50, 50);
   painter.Paint(&canvas, bounds);
 
   SkBitmap result;
   const SkISize size = canvas.sk_canvas()->getDeviceSize();
   result.allocN32Pixels(size.width(), size.height());
   canvas.sk_canvas()->readPixels(&result, 0, 0);
 
-  SkIRect green_rect = SkIRect::MakeLTRB(40, 20, 360, 180);
-  for (int y = 0; y < 200; y++) {
-    for (int x = 0; x < 400; x++) {
-      if (green_rect.contains(x, y)) {
-        ASSERT_EQ(SK_ColorGREEN, result.getColor(x, y));
+  gfx::Vector2d paint_offset(40, 20);  // Translated 20,10 with 2x dpi.

[Peter Kasting, 2015/10/29 21:26:15]

Why not store the original translation vector from above in a temp, then scale
it here by the image_scale you chose?  Then there's no need for magic numbers
with comments.

Same applies to the places below where we could programmatically calculate this
similarly.

[danakj, 2015/10/29 22:15:12]

Sure, done. Except the negative one is weird, I think I need a comment there
basically to get numbers that you can both understand and get why.

+  gfx::Rect green_rect = gfx::Rect(10, 10, 80, 80) + paint_offset;
+  for (int y = paint_offset.y(); y < 100 + paint_offset.y(); y++) {

[Peter Kasting, 2015/10/29 21:26:15]

You repeat this loop several times; factor out into a helper function?

[danakj, 2015/10/29 22:15:12]

Done.

+    SCOPED_TRACE(y);
+    for (int x = paint_offset.x(); x < 100 + paint_offset.x(); x++) {
+      SCOPED_TRACE(x);
+      if (green_rect.Contains(x, y)) {
+        ASSERT_EQ(SK_ColorGREEN, result.getColor(x, y))
+            << "Output image:\n" << GetPNGDataUrl(result);
       } else {
-        ASSERT_EQ(SK_ColorRED, result.getColor(x, y));
+        ASSERT_EQ(SK_ColorRED, result.getColor(x, y)) << "Output image:\n"
+                                                      << GetPNGDataUrl(result);
       }
     }
   }
 }
 
 TEST(NineImagePainterTest, PaintStaysInBounds) {
   // In this test the bounds rect is 1x1 but each image is 2x2.
   // The NineImagePainter should not paint outside the bounds.
 
   SkBitmap src;
@@ skipping 55 matching lines @@
     for (int x = 1; x < 10; x++) {
       if (green_rect.contains(x, y)) {
         ASSERT_EQ(SK_ColorGREEN, result.getColor(x, y));
       } else {
         ASSERT_EQ(SK_ColorRED, result.getColor(x, y));
       }
     }
   }
 }
 
-TEST(NineImagePainterTest, PaintWithNagativeScale) {
+TEST(NineImagePainterTest, PaintWithScale) {
   SkBitmap src;
   src.allocN32Pixels(100, 100);
   src.eraseColor(SK_ColorRED);
   src.eraseArea(SkIRect::MakeXYWH(10, 10, 80, 80), SK_ColorGREEN);
 
-  gfx::ImageSkia image(gfx::ImageSkiaRep(src, 0.0f));
+  float image_scale = 2.f;
+
+  gfx::ImageSkia image(gfx::ImageSkiaRep(src, image_scale));
   gfx::Insets insets(10, 10, 10, 10);
   gfx::NineImagePainter painter(image, insets);
 
-  int image_scale = 2;
   bool is_opaque = true;
   gfx::Canvas canvas(gfx::Size(400, 400), image_scale, is_opaque);
-  canvas.Translate(gfx::Vector2d(200, 200));
-  canvas.Scale(-2, -1);
+  canvas.Translate(gfx::Vector2d(20, 10));
+  canvas.Scale(2, 1);
 
-  gfx::Rect bounds(0, 0, 100, 100);
+  gfx::Rect bounds(0, 0, 50, 50);
   painter.Paint(&canvas, bounds);
 
   SkBitmap result;
   const SkISize size = canvas.sk_canvas()->getDeviceSize();
   result.allocN32Pixels(size.width(), size.height());
   canvas.sk_canvas()->readPixels(&result, 0, 0);
 
-  SkIRect green_rect = SkIRect::MakeLTRB(40, 220, 360, 380);
-  for (int y = 200; y < 400; y++) {
-    for (int x = 0; x < 400; x++) {
-      if (green_rect.contains(x, y)) {
-        ASSERT_EQ(SK_ColorGREEN, result.getColor(x, y));
+  gfx::Vector2d paint_offset(40, 20);  // Translated 20,10 with 2x dpi.
+  gfx::Rect green_rect = gfx::Rect(20, 10, 160, 80) + paint_offset;
+  for (int y = paint_offset.y(); y < 100 + paint_offset.y(); y++) {
+    SCOPED_TRACE(y);
+    for (int x = paint_offset.x(); x < 200 + paint_offset.x(); x++) {
+      SCOPED_TRACE(x);
+      if (green_rect.Contains(x, y)) {
+        ASSERT_EQ(SK_ColorGREEN, result.getColor(x, y))
+            << "Output image:\n" << GetPNGDataUrl(result);
       } else {
-        ASSERT_EQ(SK_ColorRED, result.getColor(x, y));
+        ASSERT_EQ(SK_ColorRED, result.getColor(x, y)) << "Output image:\n"
+                                                      << GetPNGDataUrl(result);
       }
     }
   }
+}
+
+TEST(NineImagePainterTest, PaintWithNegativeScale) {
+  SkBitmap src;
+  src.allocN32Pixels(100, 100);
+  src.eraseColor(SK_ColorRED);
+  src.eraseArea(SkIRect::MakeXYWH(10, 10, 80, 80), SK_ColorGREEN);
+
+  float image_scale = 2.f;
+
+  gfx::ImageSkia image(gfx::ImageSkiaRep(src, image_scale));
+  gfx::Insets insets(10, 10, 10, 10);
+  gfx::NineImagePainter painter(image, insets);
+
+  bool is_opaque = true;
+  gfx::Canvas canvas(gfx::Size(400, 400), image_scale, is_opaque);
+  canvas.Translate(gfx::Vector2d(70, 60));
+  canvas.Scale(-1, -1);
+
+  gfx::Rect bounds(0, 0, 50, 50);
+  painter.Paint(&canvas, bounds);
+
+  SkBitmap result;
+  const SkISize size = canvas.sk_canvas()->getDeviceSize();
+  result.allocN32Pixels(size.width(), size.height());
+  canvas.sk_canvas()->readPixels(&result, 0, 0);
+
+  // The painting space is 50x50 and the scale of -1m-1 means an offset of 50,50
+  // would put the output in the top left corner. Since the offset is 70,60 it
+  // moves by 20,10. Since the output is 2x DPI it will become offset by 40,20.
+  gfx::Vector2d paint_offset(40, 20);
+  gfx::Rect green_rect = gfx::Rect(10, 10, 80, 80) + paint_offset;
+  for (int y = paint_offset.y(); y < 100 + paint_offset.y(); y++) {
+    SCOPED_TRACE(y);
+    for (int x = paint_offset.x(); x < 100 + paint_offset.x(); x++) {
+      SCOPED_TRACE(x);
+      if (green_rect.Contains(x, y)) {
+        ASSERT_EQ(SK_ColorGREEN, result.getColor(x, y))
+            << "Output image:\n" << GetPNGDataUrl(result);
+      } else {
+        ASSERT_EQ(SK_ColorRED, result.getColor(x, y)) << "Output image:\n"
+                                                      << GetPNGDataUrl(result);
+      }
+    }
+  }
 }
 
 }  // namespace gfx