调用堆栈
EventSystem.Update -> BaseInputModule.Process -> StandaloneInputModule.Process ->StandaloneInputModule.ProcessTouchEvents
//Event.Update
protected virtual void Update()
{
if (current != this)
return;
TickModules();
bool changedModule = false;
for (var i = 0; i < m_SystemInputModules.Count; i++)
{
var module = m_SystemInputModules[i];
if (module.IsModuleSupported() && module.ShouldActivateModule())
{
if (m_CurrentInputModule != module)
{
ChangeEventModule(module);
changedModule = true;
}
break;
}
}
// no event module set... set the first valid one...
if (m_CurrentInputModule == null)
{
for (var i = 0; i < m_SystemInputModules.Count; i++)
{
var module = m_SystemInputModules[i];
if (module.IsModuleSupported())
{
ChangeEventModule(module);
changedModule = true;
break;
}
}
}
//调用InputModule的Process方法
if (!changedModule && m_CurrentInputModule != null)
m_CurrentInputModule.Process();
}
//StandaloneInputModule .Process
public override void Process()
{
if (!eventSystem.isFocused && ShouldIgnoreEventsOnNoFocus())
return;
bool usedEvent = SendUpdateEventToSelectedObject();
if (eventSystem.sendNavigationEvents)
{
if (!usedEvent)
usedEvent |= SendMoveEventToSelectedObject();
if (!usedEvent)
SendSubmitEventToSelectedObject();
}
// touch needs to take precedence because of the mouse emulation layer
//处理事件
if (!ProcessTouchEvents() && input.mousePresent)
ProcessMouseEvent();
}
//StandaloneInputModule .ProcessTouchEvents
private bool ProcessTouchEvents()
{
for (int i = 0; i < input.touchCount; ++i)
{
Touch touch = input.GetTouch(i);
if (touch.type == TouchType.Indirect)
continue;
bool released;
bool pressed;
var pointer = GetTouchPointerEventData(touch, out pressed, out released); //获取当前事件响应的对象
pressed和released分边表示是否为事件开始和事件结束
ProcessTouchPress(pointer, pressed, released);//分别处理事件的开端和结束
if (!released)
{
ProcessMove(pointer);//处理move事件
ProcessDrag(pointer);//处理drag事件
}
else
RemovePointerData(pointer);
}
return input.touchCount > 0;
}
- 获取事件响应raycast对象，并返回该事件是否为开始或结束事件
///
/// Given a touch populate the PointerEventData and return if we are pressed or released.
///
/// Touch being processed
/// Are we pressed this frame
/// Are we released this frame
/// - 处理初始化事件点和释放事件点
///
/// This method is called by Unity whenever a touch event is processed. Override this method with a custom implementation to process touch events yourself.
///
/// Event data relating to the touch event, such as position and ID to be passed to the touch event destination object.
/// This is true for the first frame of a touch event, and false thereafter. This can therefore be used to determine the instant a touch event occurred.
/// This is true only for the last frame of a touch event.
///
/// This method can be overridden in derived classes to change how touch press events are handled.
///
protected void ProcessTouchPress(PointerEventData pointerEvent, bool pressed, bool released)
{
var currentOverGo = pointerEvent.pointerCurrentRaycast.gameObject;
// PointerDown notification
if (pressed)
{
pointerEvent.eligibleForClick = true;
pointerEvent.delta = Vector2.zero;
pointerEvent.dragging = false;
pointerEvent.useDragThreshold = true;
pointerEvent.pressPosition = pointerEvent.position;
pointerEvent.pointerPressRaycast = pointerEvent.pointerCurrentRaycast;
DeselectIfSelectionChanged(currentOverGo, pointerEvent);
if (pointerEvent.pointerEnter != currentOverGo)
{
// send a pointer enter to the touched element if it isn't the one to select...
HandlePointerExitAndEnter(pointerEvent, currentOverGo);
pointerEvent.pointerEnter = currentOverGo;
}
//获取并执行实现pointerDownHandler的对象方法
// search for the control that will receive the press
// if we can't find a press handler set the press
// handler to be what would receive a click.
var newPressed = ExecuteEvents.ExecuteHierarchy(currentOverGo, pointerEvent, ExecuteEvents.pointerDownHandler);
//从当前响应Graphic对象节点冒泡寻找第一个实现IPointerClickHandler的脚本对象
// didnt find a press handler... search for a click handler
if (newPressed == null)
newPressed = ExecuteEvents.GetEventHandler(currentOverGo);
// Debug.Log("Pressed: " + newPressed);
float time = Time.unscaledTime;
if (newPressed == pointerEvent.lastPress)
{
var diffTime = time - pointerEvent.clickTime;
if (diffTime < 0.3f)
++pointerEvent.clickCount;
else
pointerEvent.clickCount = 1;
pointerEvent.clickTime = time;
}
else
{
pointerEvent.clickCount = 1;
}
pointerEvent.pointerPress = newPressed;
pointerEvent.rawPointerPress = currentOverGo;
pointerEvent.clickTime = time;
// Save the drag handler as well
pointerEvent.pointerDrag = ExecuteEvents.GetEventHandler(currentOverGo);
if (pointerEvent.pointerDrag != null)
ExecuteEvents.Execute(pointerEvent.pointerDrag, pointerEvent, ExecuteEvents.initializePotentialDrag);
m_InputPointerEvent = pointerEvent;
}
// PointerUp notification
if (released)
{
// Debug.Log("Executing pressup on: " + pointer.pointerPress);
ExecuteEvents.Execute(pointerEvent.pointerPress, pointerEvent, ExecuteEvents.pointerUpHandler);
// Debug.Log("KeyCode: " + pointer.eventData.keyCode);
// see if we mouse up on the same element that we clicked on...
var pointerUpHandler = ExecuteEvents.GetEventHandler(currentOverGo);
// PointerClick and Drop events
if (pointerEvent.pointerPress == pointerUpHandler && pointerEvent.eligibleForClick)
{
ExecuteEvents.Execute(pointerEvent.pointerPress, pointerEvent, ExecuteEvents.pointerClickHandler);
}
else if (pointerEvent.pointerDrag != null && pointerEvent.dragging)
{
ExecuteEvents.ExecuteHierarchy(currentOverGo, pointerEvent, ExecuteEvents.dropHandler);
}
pointerEvent.eligibleForClick = false;
pointerEvent.pointerPress = null;
pointerEvent.rawPointerPress = null;
if (pointerEvent.pointerDrag != null && pointerEvent.dragging)
ExecuteEvents.Execute(pointerEvent.pointerDrag, pointerEvent, ExecuteEvents.endDragHandler);
pointerEvent.dragging = false;
pointerEvent.pointerDrag = null;
// send exit events as we need to simulate this on touch up on touch device
ExecuteEvents.ExecuteHierarchy(pointerEvent.pointerEnter, pointerEvent, ExecuteEvents.pointerExitHandler);
pointerEvent.pointerEnter = null;
m_InputPointerEvent = pointerEvent;
}
}
//处理拖拽事件
///
/// Process the drag for the current frame with the given pointer event.
///
protected virtual void ProcessDrag(PointerEventData pointerEvent)
{
if (!pointerEvent.IsPointerMoving() ||
Cursor.lockState == CursorLockMode.Locked ||
pointerEvent.pointerDrag == null)
return;
if (!pointerEvent.dragging
&& ShouldStartDrag(pointerEvent.pressPosition, pointerEvent.position, eventSystem.pixelDragThreshold, pointerEvent.useDragThreshold))
{
ExecuteEvents.Execute(pointerEvent.pointerDrag, pointerEvent, ExecuteEvents.beginDragHandler);
pointerEvent.dragging = true;
}
// Drag notification
if (pointerEvent.dragging)
{
// Before doing drag we should cancel any pointer down state
// And clear selection!
if (pointerEvent.pointerPress != pointerEvent.pointerDrag)
{
ExecuteEvents.Execute(pointerEvent.pointerPress, pointerEvent, ExecuteEvents.pointerUpHandler);
pointerEvent.eligibleForClick = false;
pointerEvent.pointerPress = null;
pointerEvent.rawPointerPress = null;
}
ExecuteEvents.Execute(pointerEvent.pointerDrag, pointerEvent, ExecuteEvents.dragHandler);
}
}