Always fit the wallpaper to the native display resolution when the layout is WALLPAPER_LAYOUT_CENTER to prevent blurry image.

BUG=515660

Review URL: https://codereview.chromium.org/1268853006

Cr-Commit-Position: refs/heads/master@{#346657}

3 files changed, 115 insertions, 15 deletions

diff --git a/ash/desktop_background/desktop_background_controller_unittest.cc b/ash/desktop_background/desktop_background_controller_unittest.cc
index b51fca1..b1df3ec 100644
--- a/ash/desktop_background/desktop_background_controller_unittest.cc
+++ b/ash/desktop_background/desktop_background_controller_unittest.cc
@@ -8,6 +8,7 @@
 #include <cstdlib>
 
 #include "ash/ash_switches.h"
+#include "ash/desktop_background/desktop_background_view.h"
 #include "ash/desktop_background/desktop_background_widget_controller.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
@@ -15,13 +16,16 @@
 #include "ash/test/ash_test_base.h"
 #include "ash/test/test_user_wallpaper_delegate.h"
 #include "base/message_loop/message_loop.h"
+#include "base/strings/stringprintf.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "content/public/test/test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
 #include "ui/compositor/test/layer_animator_test_controller.h"
+#include "ui/gfx/canvas.h"
 
 using aura::RootWindow;
 using aura::Window;
@@ -89,6 +93,16 @@ class DesktopBackgroundControllerTest : public test::AshTestBase {
     controller_->set_wallpaper_reload_delay_for_test(0);
   }
 
+  DesktopBackgroundView* desktop_background_view() {
+    DesktopBackgroundWidgetController* controller =
+        Shell::GetPrimaryRootWindowController()
+            ->animating_wallpaper_controller()
+            ->GetController(false);
+    EXPECT_TRUE(controller);
+    return static_cast<DesktopBackgroundView*>(
+        controller->widget()->GetContentsView()->child_at(0));
+  }
+
  protected:
   // A color that can be passed to CreateImage(). Specifically chosen to not
   // conflict with any of the default wallpaper colors.
@@ -103,6 +117,37 @@ class DesktopBackgroundControllerTest : public test::AshTestBase {
     return image;
   }
 
+  // Helper function that tests the wallpaper is always fitted to the native
+  // display resolution when the layout is WALLPAPER_LAYOUT_CENTER.
+  void WallpaperFitToNativeResolution(DesktopBackgroundView* view,
+                                      float device_scale_factor,
+                                      int image_width,
+                                      int image_height,
+                                      SkColor color) {
+    gfx::Size size = view->bounds().size();
+    gfx::Canvas canvas(size, device_scale_factor, true);
+    view->OnPaint(&canvas);
+
+    int canvas_width = canvas.sk_canvas()->imageInfo().width();
+    int canvas_height = canvas.sk_canvas()->imageInfo().height();
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(canvas_width, canvas_height);
+    canvas.sk_canvas()->readPixels(&bitmap, 0, 0);
+
+    for (int i = 0; i < canvas_width; i++) {
+      for (int j = 0; j < canvas_height; j++) {
+        if (i >= (canvas_width - image_width) / 2 &&
+            i < (canvas_width + image_width) / 2 &&
+            j >= (canvas_height - image_height) / 2 &&
+            j < (canvas_height + image_height) / 2) {
+          EXPECT_EQ(color, bitmap.getColor(i, j));
+        } else {
+          EXPECT_EQ(SK_ColorBLACK, bitmap.getColor(i, j));
+        }
+      }
+    }
+  }
+
   // Runs kAnimatingDesktopController's animation to completion.
   // TODO(bshe): Don't require tests to run animations; it's slow.
   void RunDesktopControllerAnimation() {
@@ -345,5 +390,70 @@ TEST_F(DesktopBackgroundControllerTest, GetMaxDisplaySize) {
       DesktopBackgroundController::GetMaxDisplaySizeInNative().ToString());
 }
 
+// Test that the wallpaper is always fitted to the native display resolution
+// when the layout is WALLPAPER_LAYOUT_CENTER to prevent blurry images.
+TEST_F(DesktopBackgroundControllerTest, DontSacleWallpaperWithCenterLayout) {
+  // We cannot short-circuit animations for this test.
+  ui::ScopedAnimationDurationScaleMode test_duration_mode(
+      ui::ScopedAnimationDurationScaleMode::NON_ZERO_DURATION);
+
+  const gfx::Size high_resolution(3600, 2400);
+  const gfx::Size low_resolution(360, 240);
+  const float high_dsf = 2.0f;
+  const float low_dsf = 1.0f;
+
+  gfx::ImageSkia image_high_res = CreateImage(
+      high_resolution.width(), high_resolution.height(), kCustomWallpaperColor);
+  gfx::ImageSkia image_low_res = CreateImage(
+      low_resolution.width(), low_resolution.height(), kCustomWallpaperColor);
+
+  UpdateDisplay("1200x600*2");
+  {
+    SCOPED_TRACE(base::StringPrintf("1200x600*2 high resolution"));
+    controller_->SetWallpaperImage(image_high_res, WALLPAPER_LAYOUT_CENTER);
+    WallpaperFitToNativeResolution(
+        desktop_background_view(), high_dsf, high_resolution.width(),
+        high_resolution.height(), kCustomWallpaperColor);
+  }
+  {
+    SCOPED_TRACE(base::StringPrintf("1200x600*2 low resolution"));
+    controller_->SetWallpaperImage(image_low_res, WALLPAPER_LAYOUT_CENTER);
+    WallpaperFitToNativeResolution(
+        desktop_background_view(), high_dsf, low_resolution.width(),
+        low_resolution.height(), kCustomWallpaperColor);
+  }
+
+  UpdateDisplay("1200x600");
+  {
+    SCOPED_TRACE(base::StringPrintf("1200x600 high resolution"));
+    controller_->SetWallpaperImage(image_high_res, WALLPAPER_LAYOUT_CENTER);
+    WallpaperFitToNativeResolution(
+        desktop_background_view(), low_dsf, high_resolution.width(),
+        high_resolution.height(), kCustomWallpaperColor);
+  }
+  {
+    SCOPED_TRACE(base::StringPrintf("1200x600 low resolution"));
+    controller_->SetWallpaperImage(image_low_res, WALLPAPER_LAYOUT_CENTER);
+    WallpaperFitToNativeResolution(
+        desktop_background_view(), low_dsf, low_resolution.width(),
+        low_resolution.height(), kCustomWallpaperColor);
+  }
+
+  UpdateDisplay("1200x600/u@1.5");  // 1.5 ui scale
+  {
+    SCOPED_TRACE(base::StringPrintf("1200x600/u@1.5 high resolution"));
+    controller_->SetWallpaperImage(image_high_res, WALLPAPER_LAYOUT_CENTER);
+    WallpaperFitToNativeResolution(
+        desktop_background_view(), low_dsf, high_resolution.width(),
+        high_resolution.height(), kCustomWallpaperColor);
+  }
+  {
+    SCOPED_TRACE(base::StringPrintf("1200x600/u@1.5 low resolution"));
+    controller_->SetWallpaperImage(image_low_res, WALLPAPER_LAYOUT_CENTER);
+    WallpaperFitToNativeResolution(
+        desktop_background_view(), low_dsf, low_resolution.width(),
+        low_resolution.height(), kCustomWallpaperColor);
+  }
+}
 
 }  // namespace ash
diff --git a/ash/desktop_background/desktop_background_view.cc b/ash/desktop_background/desktop_background_view.cc
index 7107898..6975c11 100644
--- a/ash/desktop_background/desktop_background_view.cc
+++ b/ash/desktop_background/desktop_background_view.cc
@@ -142,21 +142,6 @@ void DesktopBackgroundView::OnPaint(gfx::Canvas* canvas) {
     return;
   }
 
-  gfx::NativeView native_view = GetWidget()->GetNativeView();
-  gfx::Display display = gfx::Screen::GetScreenFor(native_view)->
-      GetDisplayNearestWindow(native_view);
-
-  DisplayManager* display_manager = Shell::GetInstance()->display_manager();
-  DisplayInfo display_info = display_manager->GetDisplayInfo(display.id());
-  float scaling = display_info.GetEffectiveUIScale();
-  if (scaling <= 1.0f)
-    scaling = 1.0f;
-  // Allow scaling up to the UI scaling.
-  // TODO(oshima): Create separate layer that fits to the image and then
-  // scale to avoid artifacts and be more efficient when clipped.
-  gfx::Rect wallpaper_rect(
-      0, 0, wallpaper.width() * scaling, wallpaper.height() * scaling);
-
   if (wallpaper_layout == WALLPAPER_LAYOUT_CENTER_CROPPED) {
     // The dimension with the smallest ratio must be cropped, the other one
     // is preserved. Both are set in gfx::Size cropped_size.
@@ -193,6 +178,9 @@ void DesktopBackgroundView::OnPaint(gfx::Canvas* canvas) {
   } else {
     // Fill with black to make sure that the entire area is opaque.
     canvas->FillRect(GetLocalBounds(), SK_ColorBLACK);
+    float image_scale = canvas->image_scale();
+    gfx::Rect wallpaper_rect(0, 0, wallpaper.width() / image_scale,
+                             wallpaper.height() / image_scale);
     // All other are simply centered, and not scaled (but may be clipped).
     canvas->DrawImageInt(
         wallpaper,
diff --git a/ash/desktop_background/desktop_background_view.h b/ash/desktop_background/desktop_background_view.h
index 17814d0..1c76351 100644
--- a/ash/desktop_background/desktop_background_view.h
+++ b/ash/desktop_background/desktop_background_view.h
@@ -21,6 +21,8 @@ class DesktopBackgroundView : public views::View,
   ~DesktopBackgroundView() override;
 
  private:
+  friend class DesktopBackgroundControllerTest;
+
   // Overridden from views::View:
   void OnPaint(gfx::Canvas* canvas) override;
   bool OnMousePressed(const ui::MouseEvent& event) override;