Support for Adaptive Handle Orientation

ui/touch_selection/touch_handle.cc

Index: ui/touch_selection/touch_handle.cc
diff --git a/ui/touch_selection/touch_handle.cc b/ui/touch_selection/touch_handle.cc
index 0f28c3fedf8d69068acba4969db54e13cbd60bda..9d54423030b8bc1da6dd1fd9e587feb9979dd970 100644
--- a/ui/touch_selection/touch_handle.cc
+++ b/ui/touch_selection/touch_handle.cc
@@ -73,10 +73,12 @@ TouchHandle::TouchHandle(TouchHandleClient* client,
       enabled_(true),
       is_visible_(false),
       is_dragging_(false),
-      is_drag_within_tap_region_(false) {
+      is_drag_within_tap_region_(false),
+      mirror_vertical_(false),
+      mirror_horizontal_(false) {
   DCHECK_NE(orientation, TouchHandleOrientation::UNDEFINED);
   drawable_->SetEnabled(enabled_);
-  drawable_->SetOrientation(orientation_);
+  drawable_->SetOrientation(orientation_, false, false);
   drawable_->SetAlpha(alpha_);
   drawable_->SetFocus(position_);
 }
@@ -130,19 +132,55 @@ void TouchHandle::SetPosition(const gfx::PointF& position) {
     drawable_->SetFocus(position_);
 }
 
-void TouchHandle::SetOrientation(TouchHandleOrientation orientation) {
+void TouchHandle::SetOrientation(TouchHandleOrientation orientation,
+                                 const gfx::RectF viewport_rect,
+                                 const gfx::PointF handle_bottom) {
   DCHECK(enabled_);
   DCHECK_NE(orientation, TouchHandleOrientation::UNDEFINED);
   if (is_dragging_) {
     deferred_orientation_ = orientation;
+    deferred_viewport_rect_ = viewport_rect;
+    deferred_handle_bottom_ = handle_bottom;
     return;
   }
   DCHECK_EQ(deferred_orientation_, TouchHandleOrientation::UNDEFINED);
-  if (orientation_ == orientation)
+
+  bool mirror_state_changed =
+      SetInvertHandleParameters(viewport_rect, handle_bottom);
+  if (orientation_ == orientation && !mirror_state_changed)
     return;
 
   orientation_ = orientation;
-  drawable_->SetOrientation(orientation);
+  drawable_->SetOrientation(orientation, mirror_vertical_, mirror_horizontal_);
+}
+
+bool TouchHandle::SetInvertHandleParameters(const gfx::RectF viewport_rect,
+                                            const gfx::PointF handle_bottom) {
+  bool mirror_vertical = false;
+  bool mirror_horizontal = false;
+  bool mirror_state_changed = false;
+  gfx::RectF handle_bounds = drawable_->GetVisibleBounds();
+
+  if (handle_bottom.y() + handle_bounds.height() > viewport_rect.bottom()) {
+    mirror_vertical = true;
+  }
+
+  if (orientation_ == TouchHandleOrientation::LEFT &&
+      handle_bottom.x() - handle_bounds.width() < viewport_rect.x()) {
+    mirror_horizontal = true;
+  }
+
+  if (orientation_ == TouchHandleOrientation::RIGHT &&
+      handle_bottom.x() + handle_bounds.width() > viewport_rect.right()) {
+    mirror_horizontal = true;
+  }
+
+  mirror_state_changed = mirror_vertical_ != mirror_vertical ||
+                         mirror_horizontal_ != mirror_horizontal;
+  mirror_vertical_ = mirror_vertical;
+  mirror_horizontal_ = mirror_horizontal;
+
+  return mirror_state_changed;
 }
 
 bool TouchHandle::WillHandleTouchEvent(const MotionEvent& event) {
@@ -250,7 +288,8 @@ void TouchHandle::EndDrag() {
   if (deferred_orientation_ != TouchHandleOrientation::UNDEFINED) {
     TouchHandleOrientation deferred_orientation = deferred_orientation_;
     deferred_orientation_ = TouchHandleOrientation::UNDEFINED;
-    SetOrientation(deferred_orientation);
+    SetOrientation(deferred_orientation, deferred_viewport_rect_,
+                   deferred_handle_bottom_);
   }
 
   if (animate_deferred_fade_) {
@@ -294,4 +333,8 @@ void TouchHandle::SetAlpha(float alpha) {
   drawable_->SetAlpha(alpha);
 }
 
+gfx::RectF TouchHandle::GetHandleBounds() {
+  return drawable_->GetVisibleBounds();
+}
+
 }  // namespace ui