CrOS: Use foreground blur for lock screen.

Using foreground blur make it possible to cache the render surface and
provide good performance.

Bug: 738185
Test: tested locally.
Change-Id: I838c072ecd4deeb9e181e08644d215877616f0ef
Reviewed-on: https://chromium-review.googlesource.com/578713
Commit-Queue: Tao Wu <wutao@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488618}

ash/login/ui/lock_screen.cc

@@ -9,11 +9,14 @@
 #include "ash/login/ui/lock_window.h"
 #include "ash/login/ui/login_data_dispatcher.h"
 #include "ash/public/interfaces/session_controller.mojom.h"
+#include "ash/root_window_controller.h"
 #include "ash/session/session_controller.h"
 #include "ash/shell.h"
+#include "ash/wallpaper/wallpaper_widget_controller.h"
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "chromeos/chromeos_switches.h"
+#include "ui/compositor/layer.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 
@@ -28,6 +31,13 @@ views::View* BuildContentsView(LoginDataDispatcher* data_dispatcher) {
   return new LockContentsView(data_dispatcher);
 }
 
+ui::Layer* GetWallpaperLayerForWindow(aura::Window* window) {
+  return RootWindowController::ForWindow(window)
+      ->wallpaper_widget_controller()
+      ->widget()
+      ->GetLayer();
+}
+
 // Global lock screen instance. There can only ever be on lock screen at a
 // time.
 LockScreen* instance_ = nullptr;
@@ -67,22 +77,38 @@ void LockScreen::Show() {
   window->set_data_dispatcher(std::move(data_dispatcher));
   window->Show();
 
+  for (aura::Window* window : Shell::GetAllRootWindows()) {
+    ui::Layer* layer = GetWallpaperLayerForWindow(window);
+    instance_->initial_blur_[layer] = layer->layer_blur();
+  }
   instance_->ToggleBlur();
 }
 
 void LockScreen::Destroy() {
   CHECK_EQ(instance_, this);
+
+  for (aura::Window* window : Shell::GetAllRootWindows()) {
+    ui::Layer* layer = GetWallpaperLayerForWindow(window);
+    auto it = initial_blur_.find(layer);
+    if (it != initial_blur_.end())
+      layer->SetLayerBlur(it->second);
+  }
   window_->Close();
   delete instance_;
   instance_ = nullptr;
 }
 
 void LockScreen::ToggleBlur() {
-  if (instance_->window_->GetLayer()->background_blur() == 0) {
-    // TODO(jdufault): Use correct blur amount.
-    instance_->window_->GetLayer()->SetBackgroundBlur(20);
-  } else {
-    instance_->window_->GetLayer()->SetBackgroundBlur(0);
+  // TODO(jdufault): Use correct blur amount.
+  float target_blur = 20.0f;
+
+  for (aura::Window* window : Shell::GetAllRootWindows()) {
+    ui::Layer* layer = GetWallpaperLayerForWindow(window);
+    if (layer->layer_blur() == target_blur) {
+      layer->SetLayerBlur(0.0f);
+    } else {
+      layer->SetLayerBlur(target_blur);
+    }
   }
 }
 

ash/login/ui/lock_screen.h

@@ -5,11 +5,17 @@
 #ifndef ASH_LOGIN_UI_LOCK_SCREEN_H_
 #define ASH_LOGIN_UI_LOCK_SCREEN_H_
 
+#include <unordered_map>
+
 #include "ash/ash_export.h"
 #include "base/macros.h"
 
 class AccountId;
 
+namespace ui {
+class Layer;
+}
+
 namespace ash {
 
 class LockWindow;
@@ -40,6 +46,9 @@ class LockScreen {
   // Unowned pointer to the window which hosts the lock screen.
   LockWindow* window_ = nullptr;
 
+  // The wallpaper bluriness before entering lock_screen.
+  std::unordered_map<ui::Layer*, float> initial_blur_;
+
   DISALLOW_COPY_AND_ASSIGN(LockScreen);
 };
 

ui/compositor/layer.cc

@@ -97,6 +97,7 @@ Layer::Layer()
       layer_brightness_(0.0f),
       layer_grayscale_(0.0f),
       layer_inverted_(false),
+      layer_blur_sigma_(0.0f),
       layer_temperature_(0.0f),
       layer_blue_scale_(1.0f),
       layer_green_scale_(1.0f),
@@ -123,6 +124,7 @@ Layer::Layer(LayerType type)
       layer_brightness_(0.0f),
       layer_grayscale_(0.0f),
       layer_inverted_(false),
+      layer_blur_sigma_(0.0f),
       layer_temperature_(0.0f),
       layer_blue_scale_(1.0f),
       layer_green_scale_(1.0f),
@@ -174,6 +176,7 @@ std::unique_ptr<Layer> Layer::Clone() const {
   clone->SetLayerBrightness(GetTargetBrightness());
   clone->SetLayerGrayscale(GetTargetGrayscale());
   clone->SetLayerInverted(layer_inverted_);
+  clone->SetLayerBlur(layer_blur_sigma_);
   if (alpha_shape_)
     clone->SetAlphaShape(base::MakeUnique<SkRegion>(*alpha_shape_));
 
@@ -401,6 +404,12 @@ void Layer::SetBackgroundBlur(float blur_sigma) {
   SetLayerBackgroundFilters();
 }
 
+void Layer::SetLayerBlur(float blur_sigma) {
+  layer_blur_sigma_ = blur_sigma;
+
+  SetLayerFilters();
+}
+
 void Layer::SetLayerSaturation(float saturation) {
   layer_saturation_ = saturation;
   SetLayerFilters();
@@ -492,6 +501,10 @@ void Layer::SetLayerFilters() {
   }
   if (layer_inverted_)
     filters.Append(cc::FilterOperation::CreateInvertFilter(1.0));
+  if (layer_blur_sigma_) {
+    filters.Append(cc::FilterOperation::CreateBlurFilter(
+        layer_blur_sigma_, SkBlurImageFilter::kClamp_TileMode));
+  }
   // Brightness goes last, because the resulting colors neeed clamping, which
   // cause further color matrix filters to be applied separately. In this order,
   // they all can be combined in a single pass.

ui/compositor/layer.h

@@ -198,6 +198,10 @@ class COMPOSITOR_EXPORT Layer
   float background_blur() const { return background_blur_sigma_; }
   void SetBackgroundBlur(float blur_sigma);
 
+  // Blur pixels of this layer by 3 * this amount.
+  float layer_blur() const { return layer_blur_sigma_; }
+  void SetLayerBlur(float blur_sigma);
+
   // Saturate all pixels of this layer by this amount.
   // This effect will get "combined" with the inverted,
   // brightness and grayscale setting.
@@ -511,6 +515,7 @@ class COMPOSITOR_EXPORT Layer
   float layer_brightness_;
   float layer_grayscale_;
   bool layer_inverted_;
+  float layer_blur_sigma_;
 
   // The global color temperature value (0.0f ~ 1.0f). Used to calculate the
   // layer blue and green colors scales. 0.0f is least warm (default), and 1.0f