Move slider implemention to use pointer capture

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 16 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/html/shadow/SliderThumbElement.h"
 
 #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"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/forms/StepRange.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/html/shadow/ShadowElementNames.h"
 #include "core/input/EventHandler.h"
 #include "core/layout/LayoutSliderContainer.h"
 #include "core/layout/LayoutSliderThumb.h"
@@ skipping 41 matching lines @@
 }
 
 bool SliderThumbElement::matchesReadWritePseudoClass() const {
   return hostInput() && hostInput()->matchesReadWritePseudoClass();
 }
 
 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) {
   HTMLInputElement* input(hostInput());
   Element* trackElement = input->userAgentShadowRoot()->getElementById(
       ShadowElementNames::sliderTrack());
 
   if (!input->layoutObject() || !layoutBox() || !trackElement->layoutBox())
     return;
 
   LayoutPoint offset = LayoutPoint(
       input->layoutObject()->absoluteToLocal(FloatPoint(point), UseTransforms));
   bool isVertical = hasVerticalAppearance(input);
   bool isLeftToRightDirection = layoutBox()->style()->isLeftToRightDirection();
   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.
   LayoutPoint absoluteThumbOrigin =
       layoutBox()->absoluteBoundingBoxRectIgnoringTransforms().location();
   LayoutPoint absoluteSliderContentOrigin =
       LayoutPoint(input->layoutObject()->localToAbsolute());
   IntRect trackBoundingBox =
       trackElement->layoutObject()->absoluteBoundingBoxRectIgnoringTransforms();
   IntRect inputBoundingBox =
@@ skipping 39 matching lines @@
     return;
 
   // FIXME: This is no longer being set from renderer. Consider updating the
   // method name.
   input->setValueFromRenderer(valueString);
   if (layoutObject())
     layoutObject()->setNeedsLayoutAndFullPaintInvalidation(
         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(
         LayoutInvalidationReason::SliderValueChanged);
   if (hostInput())
     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
   // each shadow element.
   HTMLInputElement* input = hostInput();
   if (!input || input->isDisabledFormControl()) {
     stopDragging();
     HTMLDivElement::defaultEventHandler(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;
   }
 
   HTMLDivElement::defaultEventHandler(event);

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

Why not skip this? Is this "safe"? Passing pointer events through the default
handlers could be bad. Again, I have seen handlers that break with pointer
events.

 }
 
 bool SliderThumbElement::willRespondToMouseMoveEvents() {
   const HTMLInputElement* input = hostInput();
   if (input && !input->isDisabledFormControl() && m_inDragMode)
     return true;
 
   return HTMLDivElement::willRespondToMouseMoveEvents();
 }
 
@@ skipping 65 matching lines @@
 HTMLInputElement* SliderContainerElement::hostInput() const {
   return toHTMLInputElement(ownerShadowHost());
 }
 
 LayoutObject* SliderContainerElement::createLayoutObject(const ComputedStyle&) {
   return new LayoutSliderContainer(this);
 }
 
 void SliderContainerElement::defaultEventHandler(Event* event) {
   if (event->isTouchEvent()) {
     handleTouchEvent(toTouchEvent(event));

[mustaq, 2017/03/15 18:40:41]

The slider-container takes care of the TEs, which should be nuked/replaced too.

     return;
   }
 }
 
 void SliderContainerElement::handleTouchEvent(TouchEvent* event) {
   HTMLInputElement* input = hostInput();
   if (input->isDisabledFormControl())
     return;
 
   if (event->type() == EventTypeNames::touchend) {
@@ skipping 113 matching lines @@
   updateTouchEventHandlerRegistry();
   HTMLElement::didMoveToNewDocument(oldDocument);
 }
 
 void SliderContainerElement::removeAllEventListeners() {
   Node::removeAllEventListeners();
   m_hasTouchEventHandler = false;
 }
 
 }  // namespace blink