Add GetBoundingRectAfterMutations to EmbeddedViewParams to calculate the final bounding rect for platform view

ci/licenses_golden/licenses_flutter

@@ -26,6 +26,7 @@ FILE: ../../../flutter/common/task_runners.cc
 FILE: ../../../flutter/common/task_runners.h
 FILE: ../../../flutter/flow/compositor_context.cc
 FILE: ../../../flutter/flow/compositor_context.h
+FILE: ../../../flutter/flow/embedded_view_params_unittests.cc
 FILE: ../../../flutter/flow/embedded_views.cc
 FILE: ../../../flutter/flow/embedded_views.h
 FILE: ../../../flutter/flow/gl_context_switch.cc

flow/BUILD.gn

@@ -130,6 +130,7 @@ executable("flow_unittests") {
   testonly = true
 
   sources = [
+    "embedded_view_params_unittests.cc",
     "flow_run_all_unittests.cc",
     "flow_test_utils.cc",
     "flow_test_utils.h",

flow/embedded_view_params_unittests.cc

@@ -0,0 +1,98 @@
+// Copyright 2013 The Flutter 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 "flutter/flow/embedded_views.h"
+#include "flutter/fml/logging.h"
+#include "gtest/gtest.h"
+
+namespace flutter {
+namespace testing {
+
+TEST(EmbeddedViewParams, GetBoundingRectAfterMutationsWithNoMutations) {
+  MutatorsStack stack;
+  SkMatrix matrix;
+
+  EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
+  const SkRect& rect = params.finalBoundingRect();
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), 0));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 0));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), 1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.height(), 1));
+}
+
+TEST(EmbeddedViewParams, GetBoundingRectAfterMutationsWithScale) {
+  MutatorsStack stack;
+  SkMatrix matrix = SkMatrix::Scale(2, 2);
+  stack.PushTransform(matrix);
+
+  EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
+  const SkRect& rect = params.finalBoundingRect();
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), 0));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 0));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), 2));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.height(), 2));
+}
+
+TEST(EmbeddedViewParams, GetBoundingRectAfterMutationsWithTranslate) {
+  MutatorsStack stack;
+  SkMatrix matrix = SkMatrix::MakeTrans(1, 1);
+  stack.PushTransform(matrix);
+
+  EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
+  const SkRect& rect = params.finalBoundingRect();
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), 1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), 1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.height(), 1));
+}
+
+TEST(EmbeddedViewParams, GetBoundingRectAfterMutationsWithRotation90) {
+  MutatorsStack stack;
+  SkMatrix matrix;
+  matrix.setRotate(90);
+  stack.PushTransform(matrix);
+
+  EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
+  const SkRect& rect = params.finalBoundingRect();
+
+  FML_DLOG(ERROR) << rect.x();
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), -1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 0));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), 1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.height(), 1));
+}
+
+TEST(EmbeddedViewParams, GetBoundingRectAfterMutationsWithRotation45) {
+  MutatorsStack stack;
+  SkMatrix matrix;
+  matrix.setRotate(45);
+  stack.PushTransform(matrix);
+
+  EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
+  const SkRect& rect = params.finalBoundingRect();
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), -sqrt(2) / 2));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 0));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), sqrt(2)));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.height(), sqrt(2)));
+}
+
+TEST(EmbeddedViewParams,
+     GetBoundingRectAfterMutationsWithTranslateScaleAndRotation) {
+  SkMatrix matrix = SkMatrix::MakeTrans(2, 2);
+  matrix.preScale(3, 3);
+  matrix.preRotate(90);
+
+  MutatorsStack stack;
+  stack.PushTransform(matrix);
+
+  EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
+  const SkRect& rect = params.finalBoundingRect();
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), -1));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 2));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), 3));
+  ASSERT_TRUE(SkScalarNearlyEqual(rect.height(), 3));
+}
+
+}  // namespace testing
+}  // namespace flutter

flow/embedded_views.h

@@ -186,21 +186,49 @@ class EmbeddedViewParams {
  public:
   EmbeddedViewParams() = default;
 
+  EmbeddedViewParams(SkMatrix matrix,
+                     SkSize size_points,
+                     MutatorsStack mutators_stack)
+      : matrix_(matrix),
+        size_points_(size_points),
+        mutators_stack_(mutators_stack) {
+    SkPath path;
+    SkRect starting_rect = SkRect::MakeSize(size_points);
+    path.addRect(starting_rect);
+    path.transform(matrix);
+    final_bounding_rect_ = path.computeTightBounds();
+  }
+
   EmbeddedViewParams(const EmbeddedViewParams& other) {
-    offsetPixels = other.offsetPixels;
-    sizePoints = other.sizePoints;
-    mutatorsStack = other.mutatorsStack;
+    size_points_ = other.size_points_;
+    mutators_stack_ = other.mutators_stack_;
+    matrix_ = other.matrix_;
+    final_bounding_rect_ = other.final_bounding_rect_;
   };
 
-  SkPoint offsetPixels;
-  SkSize sizePoints;
-  MutatorsStack mutatorsStack;
+  // The original size of the platform view before any mutation matrix is
+  // applied.
+  const SkSize& sizePoints() const { return size_points_; };
+  // The mutators stack contains the detailed step by step mutations for this
+  // platform view.
+  const MutatorsStack& mutatorsStack() const { return mutators_stack_; };
+  // The bounding rect of the platform view after applying all the mutations.
+  //
+  // Clippings are ignored.
+  const SkRect& finalBoundingRect() const { return final_bounding_rect_; }
 
   bool operator==(const EmbeddedViewParams& other) const {
-    return offsetPixels == other.offsetPixels &&
-           sizePoints == other.sizePoints &&
-           mutatorsStack == other.mutatorsStack;
+    return size_points_ == other.size_points_ &&
+           mutators_stack_ == other.mutators_stack_ &&
+           final_bounding_rect_ == other.final_bounding_rect_ &&
+           matrix_ == other.matrix_;
   }
+
+ private:
+  SkMatrix matrix_;
+  SkSize size_points_;
+  MutatorsStack mutators_stack_;
+  SkRect final_bounding_rect_;
 };
 
 enum class PostPrerollResult { kResubmitFrame, kSuccess };

flow/layers/platform_view_layer.cc

@@ -27,11 +27,8 @@ void PlatformViewLayer::Preroll(PrerollContext* context,
   }
   context->has_platform_view = true;
   std::unique_ptr<EmbeddedViewParams> params =
-      std::make_unique<EmbeddedViewParams>();
-  params->offsetPixels =
-      SkPoint::Make(matrix.getTranslateX(), matrix.getTranslateY());
-  params->sizePoints = size_;
-  params->mutatorsStack = context->mutators_stack;
+      std::make_unique<EmbeddedViewParams>(matrix, size_,
+                                           context->mutators_stack);
   context->view_embedder->PrerollCompositeEmbeddedView(view_id_,
                                                        std::move(params));
 }

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm

@@ -407,13 +407,14 @@
 
 void FlutterPlatformViewsController::CompositeWithParams(int view_id,
                                                          const EmbeddedViewParams& params) {
-  CGRect frame = CGRectMake(0, 0, params.sizePoints.width(), params.sizePoints.height());
+  CGRect frame = CGRectMake(0, 0, params.sizePoints().width(), params.sizePoints().height());
   UIView* touchInterceptor = touch_interceptors_[view_id].get();
   touchInterceptor.layer.transform = CATransform3DIdentity;
   touchInterceptor.frame = frame;
   touchInterceptor.alpha = 1;
 
-  int currentClippingCount = CountClips(params.mutatorsStack);
+  const MutatorsStack& mutatorStack = params.mutatorsStack();
+  int currentClippingCount = CountClips(mutatorStack);
   int previousClippingCount = clip_count_[view_id];
   if (currentClippingCount != previousClippingCount) {
     clip_count_[view_id] = currentClippingCount;
@@ -424,7 +425,7 @@
         ReconstructClipViewsChain(currentClippingCount, touchInterceptor, oldPlatformViewRoot);
     root_views_[view_id] = fml::scoped_nsobject<UIView>([newPlatformViewRoot retain]);
   }
-  ApplyMutators(params.mutatorsStack, touchInterceptor);
+  ApplyMutators(mutatorStack, touchInterceptor);
 }
 
 SkCanvas* FlutterPlatformViewsController::CompositeEmbeddedView(int view_id) {

shell/platform/embedder/embedder_layers.cc

@@ -108,7 +108,7 @@ void EmbedderLayers::PushPlatformViewLayer(
     view.struct_size = sizeof(FlutterPlatformView);
     view.identifier = identifier;
 
-    const auto& mutators = params.mutatorsStack;
+    const auto& mutators = params.mutatorsStack();
 
     std::vector<const FlutterPlatformViewMutation*> mutations_array;
 
@@ -180,10 +180,10 @@ void EmbedderLayers::PushPlatformViewLayer(
   layer.platform_view = platform_views_referenced_.back().get();
 
   const auto layer_bounds =
-      SkRect::MakeXYWH(params.offsetPixels.x(),                          //
-                       params.offsetPixels.y(),                          //
-                       params.sizePoints.width() * device_pixel_ratio_,  //
-                       params.sizePoints.height() * device_pixel_ratio_  //
+      SkRect::MakeXYWH(params.finalBoundingRect().x(),                     //
+                       params.finalBoundingRect().y(),                     //
+                       params.sizePoints().width() * device_pixel_ratio_,  //
+                       params.sizePoints().height() * device_pixel_ratio_  //
       );
 
   const auto transformed_layer_bounds =