Fix measure when view is inverted

Summary:
changelog: [internal]

Vertical and horizontal inversion was not taken into account in `computeRelativeLayoutMetrics`. To fix it, we precompute frames to include inversions.

Reviewed By: mdvacca

Differential Revision: D37994809

fbshipit-source-id: 043e6f19b6fa577f61fa3c739ce2d751ef973cc3

Author: sammy-SC

ReactCommon/react/renderer/core/LayoutableShadowNode.cpp

@@ -17,6 +17,60 @@
 namespace facebook {
 namespace react {
 
+template <class T>
+using LayoutableSmallVector = butter::small_vector<T, 16>;
+
+static LayoutableSmallVector<Rect> calculateTransformedFrames(
+    LayoutableSmallVector<ShadowNode const *> const &shadowNodeList,
+    LayoutableShadowNode::LayoutInspectingPolicy policy) {
+  auto size = shadowNodeList.size();
+  auto transformedFrames = LayoutableSmallVector<Rect>{size};
+  auto transformation = Transform::Identity();
+
+  for (int i = size - 1; i >= 0; --i) {
+    auto currentShadowNode =
+        traitCast<LayoutableShadowNode const *>(shadowNodeList.at(i));
+    auto currentFrame = currentShadowNode->getLayoutMetrics().frame;
+
+    if (policy.includeTransform) {
+      if (Transform::isVerticalInversion(transformation)) {
+        auto parentShadowNode =
+            traitCast<LayoutableShadowNode const *>(shadowNodeList.at(i + 1));
+        currentFrame.origin.y =
+            parentShadowNode->getLayoutMetrics().frame.size.height -
+            currentFrame.size.height - currentFrame.origin.y;
+      }
+
+      if (Transform::isHorizontalInversion(transformation)) {
+        auto parentShadowNode =
+            traitCast<LayoutableShadowNode const *>(shadowNodeList.at(i + 1));
+        currentFrame.origin.x =
+            parentShadowNode->getLayoutMetrics().frame.size.width -
+            currentFrame.size.width - currentFrame.origin.x;
+      }
+
+      if (i != size - 1) {
+        auto parentShadowNode =
+            traitCast<LayoutableShadowNode const *>(shadowNodeList.at(i + 1));
+        auto contentOritinOffset = parentShadowNode->getContentOriginOffset();
+        if (Transform::isVerticalInversion(transformation)) {
+          contentOritinOffset.y = -contentOritinOffset.y;
+        }
+        if (Transform::isHorizontalInversion(transformation)) {
+          contentOritinOffset.x = -contentOritinOffset.x;
+        }
+        currentFrame.origin += contentOritinOffset;
+      }
+
+      transformation = transformation * currentShadowNode->getTransform();
+    }
+
+    transformedFrames[i] = currentFrame;
+  }
+
+  return transformedFrames;
+}
+
 LayoutableShadowNode::LayoutableShadowNode(
     ShadowNodeFragment const &fragment,
     ShadowNodeFamily::Shared const &family,
@@ -34,6 +88,8 @@ LayoutMetrics LayoutableShadowNode::computeRelativeLayoutMetrics(
     ShadowNodeFamily const &descendantNodeFamily,
     LayoutableShadowNode const &ancestorNode,
     LayoutInspectingPolicy policy) {
+  // Prelude.
+
   if (&descendantNodeFamily == &ancestorNode.getFamily()) {
     // Layout metrics of a node computed relatively to the same node are equal
     // to `transform`-ed layout metrics of the node with zero `origin`.
@@ -53,10 +109,12 @@ LayoutMetrics LayoutableShadowNode::computeRelativeLayoutMetrics(
     return EmptyLayoutMetrics;
   }
 
+  // ------------------------------
+
   // Step 1.
   // Creating a list of nodes that form a chain from the descender node to
   // ancestor node inclusively.
-  auto shadowNodeList = butter::small_vector<ShadowNode const *, 16>{};
+  auto shadowNodeList = LayoutableSmallVector<ShadowNode const *>{};
 
   // Finding the measured node.
   // The last element in the `AncestorList` is a pair of a parent of the node
@@ -81,6 +139,8 @@ LayoutMetrics LayoutableShadowNode::computeRelativeLayoutMetrics(
     }
   }
 
+  // ------------------------------
+
   // Step 2.
   // Computing the initial size of the measured node.
   auto descendantLayoutableNode =
@@ -90,6 +150,9 @@ LayoutMetrics LayoutableShadowNode::computeRelativeLayoutMetrics(
     return EmptyLayoutMetrics;
   }
 
+  // ------------------------------
+
+  auto transformedFrames = calculateTransformedFrames(shadowNodeList, policy);
   auto layoutMetrics = descendantLayoutableNode->getLayoutMetrics();
   auto &resultFrame = layoutMetrics.frame;
   resultFrame.origin = {0, 0};
@@ -105,7 +168,7 @@ LayoutMetrics LayoutableShadowNode::computeRelativeLayoutMetrics(
       return EmptyLayoutMetrics;
     }
 
-    auto currentFrame = currentShadowNode->getLayoutMetrics().frame;
+    auto currentFrame = transformedFrames[i];
     if (i == size - 1) {
       // If it's the last element, its origin is irrelevant.
       currentFrame.origin = {0, 0};
@@ -122,12 +185,10 @@ LayoutMetrics LayoutableShadowNode::computeRelativeLayoutMetrics(
     }
 
     resultFrame.origin += currentFrame.origin;
-
-    if (i != 0 && policy.includeTransform) {
-      resultFrame.origin += currentShadowNode->getContentOriginOffset();
-    }
   }
 
+  // ------------------------------
+
   return layoutMetrics;
 }