From 1f2543dd88397f14e899792e0cbeef88dd584d02 Mon Sep 17 00:00:00 2001
From: Michael Goderbauer <goderbauer@google.com>
Date: Fri, 21 Dec 2018 12:04:32 -0800
Subject: [PATCH 1/2] Add elevation and thickness to SemanticsNode

---
 lib/ui/semantics.dart                        | 6 ++++++
 lib/ui/semantics/semantics_node.h            | 2 ++
 lib/ui/semantics/semantics_update_builder.cc | 4 ++++
 lib/ui/semantics/semantics_update_builder.h  | 2 ++
 4 files changed, 14 insertions(+)

diff --git a/lib/ui/semantics.dart b/lib/ui/semantics.dart
index 8ebce7de15abf..e64efe3c05d67 100644
--- a/lib/ui/semantics.dart
+++ b/lib/ui/semantics.dart
@@ -618,6 +618,8 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     double scrollPosition,
     double scrollExtentMax,
     double scrollExtentMin,
+    double elevation,
+    double thickness,
     Rect rect,
     String label,
     String hint,
@@ -649,6 +651,8 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
       rect.top,
       rect.right,
       rect.bottom,
+      elevation,
+      thickness,
       label,
       hint,
       value,
@@ -676,6 +680,8 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     double top,
     double right,
     double bottom,
+    double elevation,
+    double thickness,
     String label,
     String hint,
     String value,
diff --git a/lib/ui/semantics/semantics_node.h b/lib/ui/semantics/semantics_node.h
index 4275cb7d83d30..7596dc20957e8 100644
--- a/lib/ui/semantics/semantics_node.h
+++ b/lib/ui/semantics/semantics_node.h
@@ -87,6 +87,8 @@ struct SemanticsNode {
   double scrollPosition = std::nan("");
   double scrollExtentMax = std::nan("");
   double scrollExtentMin = std::nan("");
+  double elevation = 0.0;
+  double thickness = 0.0;
   std::string label;
   std::string hint;
   std::string value;
diff --git a/lib/ui/semantics/semantics_update_builder.cc b/lib/ui/semantics/semantics_update_builder.cc
index aca1fa7e32a42..575ba6e3227d0 100644
--- a/lib/ui/semantics/semantics_update_builder.cc
+++ b/lib/ui/semantics/semantics_update_builder.cc
@@ -50,6 +50,8 @@ void SemanticsUpdateBuilder::updateNode(
     double top,
     double right,
     double bottom,
+    double elevation,
+    double thickness,
     std::string label,
     std::string hint,
     std::string value,
@@ -72,6 +74,8 @@ void SemanticsUpdateBuilder::updateNode(
   node.scrollExtentMax = scrollExtentMax;
   node.scrollExtentMin = scrollExtentMin;
   node.rect = SkRect::MakeLTRB(left, top, right, bottom);
+  node.elevation = elevation;
+  node.thickness = thickness;
   node.label = label;
   node.hint = hint;
   node.value = value;
diff --git a/lib/ui/semantics/semantics_update_builder.h b/lib/ui/semantics/semantics_update_builder.h
index ed486e260475c..ac8424d9f0fbd 100644
--- a/lib/ui/semantics/semantics_update_builder.h
+++ b/lib/ui/semantics/semantics_update_builder.h
@@ -38,6 +38,8 @@ class SemanticsUpdateBuilder
                   double top,
                   double right,
                   double bottom,
+                  double elevation,
+                  double thickness,
                   std::string label,
                   std::string hint,
                   std::string value,

From 1e40d556fd14a8692b9389755380ff82cb0210b0 Mon Sep 17 00:00:00 2001
From: Michael Goderbauer <goderbauer@google.com>
Date: Fri, 21 Dec 2018 15:08:03 -0800
Subject: [PATCH 2/2] add doc

---
 lib/ui/semantics.dart | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/ui/semantics.dart b/lib/ui/semantics.dart
index e64efe3c05d67..72576c613b7bc 100644
--- a/lib/ui/semantics.dart
+++ b/lib/ui/semantics.dart
@@ -607,6 +607,14 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
   ///
   /// The `transform` is a matrix that maps this node's coordinate system into
   /// its parent's coordinate system.
+  ///
+  /// The `elevation` describes the distance in z-direction between this node
+  /// and the `elevation` of the parent.
+  ///
+  /// The `thickness` describes how much space this node occupies in the
+  /// z-direction starting at `elevation`. Basically, in the z-direction the
+  /// node starts at `elevation` above the parent and ends at `elevation` +
+  /// `thickness` above the parent.
   void updateNode({
     int id,
     int flags,