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

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 +1,121 @@
+// 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 "gtest/gtest.h"
+#include "flutter/fml/logging.h"
+
+
+namespace flutter {
+namespace testing {
+
+TEST(EmbeddedViewParams, GetBoundingRectWithNoMutations) {
+  MutatorsStack stack;
+  EmbeddedViewParams params;
+  params.sizePoints = SkSize::Make(1, 1);;
+  params.offsetPixels = SkPoint::Make(0, 0);
+  params.mutatorsStack = stack;
+
+  SkRect rect = params.GetBoundingRect();
+  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, GetBoundingRectWithScale) {
+  MutatorsStack stack;
+  SkMatrix scale = SkMatrix::Scale(2, 2);
+  stack.PushTransform(scale);
+
+  EmbeddedViewParams params;
+  params.sizePoints = SkSize::Make(1, 1);;
+  params.offsetPixels = SkPoint::Make(0, 0);
+  params.mutatorsStack = stack;
+
+  SkRect rect = params.GetBoundingRect();
+  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, GetBoundingRectWithTranslate) {
+  MutatorsStack stack;
+  SkMatrix trans = SkMatrix::MakeTrans(1, 1);
+  stack.PushTransform(trans);
+
+  EmbeddedViewParams params;
+  params.sizePoints = SkSize::Make(1, 1);;
+  params.offsetPixels = SkPoint::Make(0, 0);
+  params.mutatorsStack = stack;
+
+  SkRect rect = params.GetBoundingRect();
+  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, GetBoundingRectWithRotation90) {
+  MutatorsStack stack;
+  SkMatrix rotate;
+  rotate.setRotate(90);
+  stack.PushTransform(rotate);
+
+  EmbeddedViewParams params;
+  params.sizePoints = SkSize::Make(1, 1);;
+  params.offsetPixels = SkPoint::Make(0, 0);
+  params.mutatorsStack = stack;
+
+  SkRect rect = params.GetBoundingRect();
+  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, GetBoundingRectWithRotation45) {
+  MutatorsStack stack;
+  SkMatrix rotate;
+  rotate.setRotate(45);
+  stack.PushTransform(rotate);
+
+  EmbeddedViewParams params;
+  params.sizePoints = SkSize::Make(1, 1);;
+  params.offsetPixels = SkPoint::Make(0, 0);
+  params.mutatorsStack = stack;
+
+  SkRect rect = params.GetBoundingRect();
+  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, GetBoundingRectWithTranslateScalingAndRotation) {
+  MutatorsStack stack;
+  SkMatrix translate = SkMatrix::MakeTrans(2, 2);
+  SkMatrix scale = SkMatrix::MakeScale(3, 3);
+  SkMatrix rotate;
+  rotate.setRotate(90);
+  stack.PushTransform(translate);
+  stack.PushTransform(scale);
+  stack.PushTransform(rotate);
+
+  EmbeddedViewParams params;
+  params.sizePoints = SkSize::Make(1, 1);;
+  params.offsetPixels = SkPoint::Make(0, 0);
+  params.mutatorsStack = stack;
+
+  SkRect rect = params.GetBoundingRect();
+  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

@@ -201,6 +201,33 @@ class EmbeddedViewParams {
            sizePoints == other.sizePoints &&
            mutatorsStack == other.mutatorsStack;
   }
+
+  // Clippings are ignored in this operation
+  // TODO(cyanglaz): Factoring clipping.
+  // https://github.com/flutter/flutter/issues/59821
+  SkRect GetBoundingRectAfterMutations() const {
+    SkPath path;
+    SkRect starting_rect = SkRect::MakeSize(sizePoints);
+    path.addRect(starting_rect);
+    std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator iter =
+        mutatorsStack.Bottom();
+    while (iter != mutatorsStack.Top()) {
+      switch ((*iter)->GetType()) {
+        case transform: {
+          const SkMatrix& matrix = (*iter)->GetMatrix();
+          path.transform(matrix);
+          break;
+        }
+        case clip_rect:
+        case clip_rrect:
+        case clip_path:
+        case opacity:
+          break;
+      }
+      ++iter;
+    }
+    return path.computeTightBounds();
+  }
 };
 
 enum class PostPrerollResult { kResubmitFrame, kSuccess };