Incorporate the device pixel ratio when drawing shadows (#3919)

flow/layers/physical_model_layer.cc

@@ -9,7 +9,7 @@
 
 namespace flow {
 
-PhysicalModelLayer::PhysicalModelLayer() : rrect_(SkRRect::MakeEmpty()) {}
+PhysicalModelLayer::PhysicalModelLayer() = default;
 
 PhysicalModelLayer::~PhysicalModelLayer() = default;
 
@@ -70,7 +70,7 @@ void PhysicalModelLayer::Paint(PaintContext& context) {
 
   if (elevation_ != 0) {
     DrawShadow(&context.canvas, path, SK_ColorBLACK, elevation_,
-               SkColorGetA(color_) != 0xff);
+               SkColorGetA(color_) != 0xff, device_pixel_ratio_);
   }
 
   SkPaint paint;
@@ -93,16 +93,17 @@ void PhysicalModelLayer::DrawShadow(SkCanvas* canvas,
                                     const SkPath& path,
                                     SkColor color,
                                     float elevation,
-                                    bool transparentOccluder) {
+                                    bool transparentOccluder,
+                                    SkScalar dpr) {
   SkShadowFlags flags = transparentOccluder
                             ? SkShadowFlags::kTransparentOccluder_ShadowFlag
                             : SkShadowFlags::kNone_ShadowFlag;
   const SkRect& bounds = path.getBounds();
   SkScalar shadow_x = (bounds.left() + bounds.right()) / 2;
   SkScalar shadow_y = bounds.top() - 600.0f;
-  SkShadowUtils::DrawShadow(canvas, path, elevation,
-                            SkPoint3::Make(shadow_x, shadow_y, 600.0f), 800.0f,
-                            0.039f, 0.25f, color, flags);
+  SkShadowUtils::DrawShadow(canvas, path, dpr * elevation,
+                            SkPoint3::Make(shadow_x, shadow_y, dpr * 600.0f),
+                            dpr * 800.0f, 0.039f, 0.25f, color, flags);
 }
 
 }  // namespace flow

flow/layers/physical_model_layer.h

@@ -17,12 +17,14 @@ class PhysicalModelLayer : public ContainerLayer {
   void set_rrect(const SkRRect& rrect) { rrect_ = rrect; }
   void set_elevation(float elevation) { elevation_ = elevation; }
   void set_color(SkColor color) { color_ = color; }
+  void set_device_pixel_ratio(SkScalar dpr) { device_pixel_ratio_ = dpr; }
 
   static void DrawShadow(SkCanvas* canvas,
                          const SkPath& path,
                          SkColor color,
                          float elevation,
-                         bool transparentOccluder);
+                         bool transparentOccluder,
+                         SkScalar dpr);
 
   void Preroll(PrerollContext* context, const SkMatrix& matrix) override;
   void Paint(PaintContext& context) override;
@@ -35,6 +37,7 @@ class PhysicalModelLayer : public ContainerLayer {
   SkRRect rrect_;
   float elevation_;
   SkColor color_;
+  SkScalar device_pixel_ratio_;
 
 #if defined(OS_FUCHSIA)
   SkScalar scale_x_;

lib/ui/compositing/scene_builder.cc

@@ -16,8 +16,10 @@
 #include "flutter/flow/layers/picture_layer.h"
 #include "flutter/flow/layers/shader_mask_layer.h"
 #include "flutter/flow/layers/transform_layer.h"
+#include "flutter/lib/ui/ui_dart_state.h"
 #include "flutter/lib/ui/painting/matrix.h"
 #include "flutter/lib/ui/painting/shader.h"
+#include "flutter/lib/ui/window/window.h"
 #include "lib/ftl/build_config.h"
 #include "lib/tonic/converter/dart_converter.h"
 #include "lib/tonic/dart_args.h"
@@ -163,11 +165,14 @@ void SceneBuilder::pushPhysicalModel(const RRect& rrect,
   if (!cullRect.intersect(rrect.sk_rrect.rect(), m_cullRects.top()))
     cullRect = SkRect::MakeEmpty();
 
+  SkScalar dpr = UIDartState::Current()->window()->viewport_metrics().device_pixel_ratio;
+
   std::unique_ptr<flow::PhysicalModelLayer> layer(
       new flow::PhysicalModelLayer());
   layer->set_rrect(rrect.sk_rrect);
   layer->set_elevation(elevation);
   layer->set_color(color);
+  layer->set_device_pixel_ratio(dpr);
   addLayer(std::move(layer), cullRect);
 }
 

lib/ui/painting/canvas.cc

@@ -7,8 +7,10 @@
 #include <math.h>
 
 #include "flutter/flow/layers/physical_model_layer.h"
+#include "flutter/lib/ui/ui_dart_state.h"
 #include "flutter/lib/ui/painting/image.h"
 #include "flutter/lib/ui/painting/matrix.h"
+#include "flutter/lib/ui/window/window.h"
 #include "lib/tonic/converter/dart_converter.h"
 #include "lib/tonic/dart_args.h"
 #include "lib/tonic/dart_binding_macros.h"
@@ -399,11 +401,13 @@ void Canvas::drawShadow(const CanvasPath* path,
                         bool transparentOccluder) {
   if (!path)
     Dart_ThrowException(ToDart("Canvas.drawShader called with non-genuine Path."));
+  SkScalar dpr = UIDartState::Current()->window()->viewport_metrics().device_pixel_ratio;
   flow::PhysicalModelLayer::DrawShadow(canvas_,
                                        path->path(),
                                        color,
                                        elevation,
-                                       transparentOccluder);
+                                       transparentOccluder,
+                                       dpr);
 }
 
 void Canvas::Clear() {

lib/ui/window/window.cc

@@ -129,6 +129,8 @@ void Window::DidCreateIsolate() {
 }
 
 void Window::UpdateWindowMetrics(const ViewportMetrics& metrics) {
+  viewport_metrics_ = metrics;
+
   tonic::DartState* dart_state = library_.dart_state().get();
   if (!dart_state)
     return;

lib/ui/window/window.h

@@ -39,6 +39,7 @@ class Window {
   ~Window();
 
   WindowClient* client() const { return client_; }
+  const ViewportMetrics& viewport_metrics() { return viewport_metrics_; }
 
   void DidCreateIsolate();
   void UpdateWindowMetrics(const ViewportMetrics& metrics);
@@ -59,6 +60,7 @@ class Window {
  private:
   WindowClient* client_;
   tonic::DartPersistentValue library_;
+  ViewportMetrics viewport_metrics_;
 
   // We use id 0 to mean that no response is expected.
   int next_response_id_ = 1;

runtime/runtime_controller.cc

@@ -45,7 +45,6 @@ void RuntimeController::CreateDartController(
 
   Window* window = GetWindow();
 
-  window->UpdateWindowMetrics(viewport_metrics_);
   window->UpdateLocale(language_code_, country_code_);
 
   if (semantics_enabled_)
@@ -53,8 +52,7 @@ void RuntimeController::CreateDartController(
 }
 
 void RuntimeController::SetViewportMetrics(const ViewportMetrics& metrics) {
-  viewport_metrics_ = metrics;
-  GetWindow()->UpdateWindowMetrics(viewport_metrics_);
+  GetWindow()->UpdateWindowMetrics(metrics);
 }
 
 void RuntimeController::SetLocale(const std::string& language_code,

runtime/runtime_controller.h

@@ -62,7 +62,6 @@ class RuntimeController : public WindowClient, public IsolateClient {
   void DidCreateSecondaryIsolate(Dart_Isolate isolate) override;
 
   RuntimeDelegate* client_;
-  ViewportMetrics viewport_metrics_;
   std::string language_code_;
   std::string country_code_;
   bool semantics_enabled_ = false;