Move slider implemention to use pointer capture

third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp

Index: third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp b/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
index c359033399174ee455fdd2d4ab7f5754a5e2b987..2fcf7572845238b7b1fe17f45ca7e514e7789510 100644
--- a/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/SliderThumbElement.cpp
@@ -34,6 +34,7 @@
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/Event.h"
 #include "core/events/MouseEvent.h"
+#include "core/events/PointerEvent.h"
 #include "core/events/TouchEvent.h"
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/LocalFrame.h"
@@ -95,9 +96,9 @@ Node* SliderThumbElement::focusDelegate() {
   return hostInput();
 }
 
-void SliderThumbElement::dragFrom(const LayoutPoint& point) {
-  startDragging();
-  setPositionFromPoint(point);
+void SliderThumbElement::dragFrom(const PointerEvent* event) {

[mustaq, 2017/03/15 18:15:41]

Please rename |dragFrom| to something like |initiateDrag|, the "drag from point"
is no longer the case.

Another nit: const PointerEvent& instead?

+  requestPointerCapture(event->pointerId());
+  setPositionFromPoint(LayoutPoint(event->absoluteLocation()));
 }
 
 void SliderThumbElement::setPositionFromPoint(const LayoutPoint& point) {
@@ -115,7 +116,7 @@ void SliderThumbElement::setPositionFromPoint(const LayoutPoint& point) {
   LayoutUnit trackSize;
   LayoutUnit position;
   LayoutUnit currentPosition;
-  // We need to calculate currentPosition from absolute points becaue the
+  // We need to calculate currentPosition from absolute points because the
   // layoutObject for this node is usually on a layer and layoutBox()->x() and
   // y() are unusable.
   // FIXME: This should probably respect transforms.
@@ -175,19 +176,13 @@ void SliderThumbElement::setPositionFromPoint(const LayoutPoint& point) {
         LayoutInvalidationReason::SliderValueChanged);
 }
 
-void SliderThumbElement::startDragging() {
-  if (LocalFrame* frame = document().frame()) {
-    frame->eventHandler().setCapturingMouseEventsNode(this);
-    m_inDragMode = true;
-  }
+inline void SliderThumbElement::startDragging() {
+  m_inDragMode = true;
 }
 
 void SliderThumbElement::stopDragging() {
   if (!m_inDragMode)
     return;
-
-  if (LocalFrame* frame = document().frame())
-    frame->eventHandler().setCapturingMouseEventsNode(nullptr);
   m_inDragMode = false;
   if (layoutObject())
     layoutObject()->setNeedsLayoutAndFullPaintInvalidation(
@@ -196,11 +191,37 @@ void SliderThumbElement::stopDragging() {
     hostInput()->dispatchFormControlChangeEvent();
 }
 
+void SliderThumbElement::requestPointerCapture(int pointerId) {
+  if (LocalFrame* frame = document().frame()) {
+    frame->eventHandler().setPointerCapture(pointerId, this);
+    m_requestedPointerIdToCapture = pointerId;
+  }
+}
+
+void SliderThumbElement::releasePointerCapture() {
+  if (LocalFrame* frame = document().frame()) {
+    frame->eventHandler().releasePointerCapture(m_requestedPointerIdToCapture,
+                                                this);
+  }
+}
+
 void SliderThumbElement::defaultEventHandler(Event* event) {
-  if (!event->isMouseEvent()) {
+  if (!event->isPointerEvent()) {
     HTMLDivElement::defaultEventHandler(event);
     return;
   }
+  PointerEvent* pointerEvent = toPointerEvent(event);
+
+  if (pointerEvent->type() == EventTypeNames::gotpointercapture &&
+      m_requestedPointerIdToCapture == pointerEvent->pointerId()) {
+    startDragging();
+    return;
+  }
+
+  if (pointerEvent->type() == EventTypeNames::lostpointercapture) {
+    stopDragging();
+    return;
+  }
 
   // FIXME: Should handle this readonly/disabled check in more general way.
   // Missing this kind of check is likely to occur elsewhere if adding it in
@@ -212,25 +233,31 @@ void SliderThumbElement::defaultEventHandler(Event* event) {
     return;
   }
 
-  MouseEvent* mouseEvent = toMouseEvent(event);
-  bool isLeftButton = mouseEvent->button() ==
+  bool isLeftButton = pointerEvent->button() ==
                       static_cast<short>(WebPointerProperties::Button::Left);
+  bool isLeftButtonActive =
+      pointerEvent->buttons() &
+      static_cast<short>(WebPointerProperties::Button::Left);
   const AtomicString& eventType = event->type();
 
   // We intentionally do not call event->setDefaultHandled() here because
   // MediaControlTimelineElement::defaultEventHandler() wants to handle these
   // mouse events.
-  if (eventType == EventTypeNames::mousedown && isLeftButton) {
-    startDragging();
+  if ((eventType == EventTypeNames::pointerdown ||
+       eventType == EventTypeNames::pointermove) &&
+      isLeftButton && isLeftButtonActive) {
+    requestPointerCapture(pointerEvent->pointerId());

[mustaq, 2017/03/15 18:15:41]

So a chorded L-down would start dragging here, right? I think initiating through
just a pointerdown with L-button is enough, old mouse code didn't anticipate the
chorded button case.

     return;
   }
-  if (eventType == EventTypeNames::mouseup && isLeftButton) {
-    stopDragging();
+  if ((eventType == EventTypeNames::pointerup ||

[mustaq, 2017/03/15 18:15:41]

May be just |if (!isLeftButtonActive) {} |?

+       eventType == EventTypeNames::pointermove) &&
+      isLeftButton && !isLeftButtonActive) {
+    releasePointerCapture();
     return;
   }
-  if (eventType == EventTypeNames::mousemove) {
+  if (eventType == EventTypeNames::pointermove) {
     if (m_inDragMode)
-      setPositionFromPoint(LayoutPoint(mouseEvent->absoluteLocation()));
+      setPositionFromPoint(LayoutPoint(pointerEvent->absoluteLocation()));
     return;
   }