事件机制在android开发中是比较常见的场景，比如：点击、双击、长按、触摸等，当然提到最多的就是View和ViewGroup的事件处理机制，事件处理机制包括：事件分发、事件拦截、事件处理，View包含：事件分发和事件处理，ViewGroup包含：事件分发、事件拦截、事件处理；接下来就看下当用于点击或者触摸默认控件(图标)时事件的流程走向吧。
Activity中就包含一个自定义的LinearLayout和一个自定的View，重写了Activity中的dispatchTouchEvent和onTouchEvent方法，
<?xml version="1.0" encoding="utf-8"?>
<com.lsm.gradlestudy.MyViewGroup xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<com.lsm.gradlestudy.MyView
android:layout_width="match_parent"
android:layout_height="100dp"
android:text="Hello World!"
android:background="@color/colorAccent"
android:gravity="center" />
</com.lsm.gradlestudy.MyViewGroup>
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
if (action == MotionEvent.ACTION_DOWN) {
Log.d(TAG, "事件处理----onTouchEvent----按下了");
} else if (action == MotionEvent.ACTION_UP) {
Log.d(TAG, "事件处理----onTouchEvent----抬起了");
} else if (action == MotionEvent.ACTION_MOVE) {
Log.d(TAG, "事件处理----onTouchEvent----移动了");
}
//返回true或者false 或者系统的默认值 都代表对事件的消费，
//不过返回false的话不会有MotionEvent.ACTION_MOVE
return super.onTouchEvent(event);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
int action = ev.getAction();
if (action == MotionEvent.ACTION_DOWN) {
Log.d(TAG, "事件处理----dispatchTouchEvent----按下了");
} else if (action == MotionEvent.ACTION_UP) {
Log.d(TAG, "事件处理----dispatchTouchEvent----抬起了");
} else if (action == MotionEvent.ACTION_MOVE) {
Log.d(TAG, "事件处理----dispatchTouchEvent----移动了");
}
//这里如果返回true或者false就不会对事件进行分发，后面的ViewGroup和View就响应不到事件了
return super.dispatchTouchEvent(ev);
}
自定义ViewGroup中重写了dispatchTouchEvent、onTouchEvent、onTnterceptTouchEvent方法，
public class MyViewGroup extends LinearLayout {
private static final String TAG=MyViewGroup.class.getSimpleName();
public MyViewGroup(Context context) {
this(context,null);
}
public MyViewGroup(Context context, @Nullable AttributeSet attrs) {
this(context, attrs,-1);
}
public MyViewGroup(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
setOrientation(LinearLayout.VERTICAL);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
if (action == MotionEvent.ACTION_DOWN) {
Log.d(TAG, "事件处理----onTouchEvent----按下了");
} else if (action == MotionEvent.ACTION_UP) {
Log.d(TAG, "事件处理----onTouchEvent----抬起了");
} else if (action == MotionEvent.ACTION_MOVE) {
Log.d(TAG, "事件处理----onTouchEvent----移动了");
}
//事件处理
return super.onTouchEvent(event);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
int action = ev.getAction();
if (action == MotionEvent.ACTION_DOWN) {
Log.d(TAG, "事件处理----dispatchTouchEvent----按下了");
} else if (action == MotionEvent.ACTION_UP) {
Log.d(TAG, "事件处理----dispatchTouchEvent----抬起了");
} else if (action == MotionEvent.ACTION_MOVE) {
Log.d(TAG, "事件处理----dispatchTouchEvent----移动了");
}
//事件分发
return super.dispatchTouchEvent(ev);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
Log.d(TAG,"事件处理----onInterceptTouchEvent");
//事件拦截
//如果返回true，代表对事件进行拦截
return super.onInterceptTouchEvent(ev);
}
}
自定义View重写了dispatchTouchEvent、onTouchEvent方法，
public class MyView extends AppCompatTextView {
private static final String TAG = MyView.class.getSimpleName();
public MyView(Context context) {
this(context, null);
}
public MyView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, -1);
}
public MyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
if (action == MotionEvent.ACTION_DOWN) {
Log.d(TAG, "事件处理----onTouchEvent----按下了");
} else if (action == MotionEvent.ACTION_UP) {
Log.d(TAG, "事件处理----onTouchEvent----抬起了");
} else if (action == MotionEvent.ACTION_MOVE) {
Log.d(TAG, "事件处理----onTouchEvent----移动了");
}
//事件处理
return super.onTouchEvent(event);
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
int action = event.getAction();
if (action == MotionEvent.ACTION_DOWN) {
Log.d(TAG, "事件处理----dispatchTouchEvent----按下了");
} else if (action == MotionEvent.ACTION_UP) {
Log.d(TAG, "事件处理----dispatchTouchEvent----抬起了");
} else if (action == MotionEvent.ACTION_MOVE) {
Log.d(TAG, "事件处理----dispatchTouchEvent----移动了");
}
//事件分发
return super.dispatchTouchEvent(event);
}
}
dispatchTouchEvent 事件分发
onTouchEvent 事件处理
onInterceptTouchEvent 事件拦截
上面重写的方法的返回值没有做修改，返回的都是系统默认的值，看下打印的日志输出，
事件机制.png
首先响应的是activity中的方法，然后是ViewGroup，最后才是点击的View控件，直到事件被消费掉，通过之前对setContentView源码的分析得知，用户看的界面，依次为:
PhoneWindow(Window)--->DecorView(FrameLayout)--->R.id.content(系统布局容器)--->自定义的布局容器--->自定义的View控件
所以得到：
其实就是ViewGroup一直将事件传递分发下去直到事件被拦截或者消费掉为止。
既然这样的话，如果activity中的dispatchTouchEvent返回true或者false的话，就不会将事件分发下去，后面的ViewGroup和View也就响应不到事件了，
事件机制0.png
这个是返回true，返回false少了MotionEvent.ACTION_MOVE，activity中onTouchEvent返回true或者false 或这系统默认值，都是对事件进行消费，返回false会少了MotionEvent.ACTION_MOVE。在activity的dispatchTouchEvent中可以看到会调用Window中的superDispatchTouchEvent方法
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
//在activity中可以重写该方法，执行一些action_down后的逻辑
onUserInteraction();
}
//调用window中的方法
if (getWindow().superDispatchTouchEvent(ev)) {
return true;
}
//调用onTouchEvent方法，判断事件是否被消费掉
//如果没有消费掉就继续分发 如果消费掉了就停止分发
return onTouchEvent(ev);
}
@Override
public boolean superDispatchTouchEvent(MotionEvent event) {
//调用了DecorView中的superDispatchTouchEvent方法
return mDecor.superDispatchTouchEvent(event);
}
在PhoneWindow中看到接着调用到了DecorView中的superDispatchTouchEvent方法，DecorView其实是继承自ViewGroup的，那其实调用的就是ViewGroup中的dispatchTouchEvent方法，
public boolean superDispatchTouchEvent(MotionEvent event) {
//DecorView中调用父类ViewGroup中的dispatchTouchEvent方法
return super.dispatchTouchEvent(event);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
}
// If the event targets the accessibility focused view and this is it, start
// normal event dispatch. Maybe a descendant is what will handle the click.
if (ev.isTargetAccessibilityFocus() && isAccessibilityFocusedViewOrHost()) {
ev.setTargetAccessibilityFocus(false);
}
//用于标记dispatchTouchEvent的返回值
boolean handled = false;
//过滤掉一些事件处理，true代表需要处理 false代表过滤
if (onFilterTouchEventForSecurity(ev)) {
//获取当前对应的事件类型 比如 是down还是up等
final int action = ev.getAction();
//获取对应事件类型的mask
final int actionMasked = action & MotionEvent.ACTION_MASK;
// Handle an initial down.
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Throw away all previous state when starting a new touch gesture.
// The framework may have dropped the up or cancel event for the previous gesture
// due to an app switch, ANR, or some other state change.
//取消和清除之前的touchTarget 在这里mFirstTouchTarget会被设置为null
cancelAndClearTouchTargets(ev);
//恢复事件的状态
resetTouchState();
}
//标识检查时间是否被拦截
// Check for interception.
final boolean intercepted;
if (actionMasked == MotionEvent.ACTION_DOWN
|| mFirstTouchTarget != null) {
//FLAG_DISALLOW_INTERCEPT 是否允许拦截的标识
final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
if (!disallowIntercept) {
//交由onInterceptTouchEvent 来觉得是否进行拦截 可以在子类中重写该方法 进行事件的拦截
intercepted = onInterceptTouchEvent(ev);
//设置事件类型
ev.setAction(action); // restore action in case it was changed
} else {
intercepted = false;
}
} else {
// There are no touch targets and this action is not an initial down
// so this view group continues to intercept touches.
//没有触摸的目标，并且不是最初的 就直接拦截该view
intercepted = true;
}
// If intercepted, start normal event dispatch. Also if there is already
// a view that is handling the gesture, do normal event dispatch.
if (intercepted || mFirstTouchTarget != null) {
ev.setTargetAccessibilityFocus(false);
}
//检测事件是否被取消
// Check for cancelation.
final boolean canceled = resetCancelNextUpFlag(this)
|| actionMasked == MotionEvent.ACTION_CANCEL;
// Update list of touch targets for pointer down, if needed.
final boolean isMouseEvent = ev.getSource() == InputDevice.SOURCE_MOUSE;
final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0
&& !isMouseEvent;
//定义事件目标实例对象
TouchTarget newTouchTarget = null;
boolean alreadyDispatchedToNewTouchTarget = false;
//如果事件没有被取消 并且没有被拦截 这个时候根据需要进行事件的分发和处理
if (!canceled && !intercepted) {
// If the event is targeting accessibility focus we give it to the
// view that has accessibility focus and if it does not handle it
// we clear the flag and dispatch the event to all children as usual.
// We are looking up the accessibility focused host to avoid keeping
// state since these events are very rare.
View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()
? findChildWithAccessibilityFocus() : null;
if (actionMasked == MotionEvent.ACTION_DOWN
|| (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)
|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
final int actionIndex = ev.getActionIndex(); // always 0 for down
final int idBitsToAssign = split ? 1 << ev.getPointerId(actionIndex)
: TouchTarget.ALL_POINTER_IDS;
// Clean up earlier touch targets for this pointer id in case they
// have become out of sync.
removePointersFromTouchTargets(idBitsToAssign);
//获取childview的数量
final int childrenCount = mChildrenCount;
//如果事件目标为null 同事布局中有子view
if (newTouchTarget == null && childrenCount != 0) {
//获取事件目标在屏幕中的位置
final float x =
isMouseEvent ? ev.getXCursorPosition() : ev.getX(actionIndex);
final float y =
isMouseEvent ? ev.getYCursorPosition() : ev.getY(actionIndex);
// Find a child that can receive the event.
// Scan children from front to back.
//寻找对应事件的view，从前到后的方式遍历view
//构建事件触摸分发处理子view列表
final ArrayList<View> preorderedList = buildTouchDispatchChildList();
final boolean customOrder = preorderedList == null
&& isChildrenDrawingOrderEnabled();
//获取容器中view
final View[] children = mChildren;
//进行对布局中view的遍历
for (int i = childrenCount - 1; i >= 0; i--) {
final int childIndex = getAndVerifyPreorderedIndex(
childrenCount, i, customOrder);
//获取对应位置的view，如果不是事件对应的view 就跳过去
final View child = getAndVerifyPreorderedView(
preorderedList, children, childIndex);
if (!child.canReceivePointerEvents()
|| !isTransformedTouchPointInView(x, y, child, null)) {
continue;
}
//获取view的事件目标
newTouchTarget = getTouchTarget(child);
if (newTouchTarget != null) {
// Child is already receiving touch within its bounds.
// Give it the new pointer in addition to the ones it is handling.
newTouchTarget.pointerIdBits |= idBitsToAssign;
break;
}
//重置一些取消的标识
resetCancelNextUpFlag(child);
//转换事件处理
if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
// Child wants to receive touch within its bounds.
mLastTouchDownTime = ev.getDownTime();
if (preorderedList != null) {
// childIndex points into presorted list, find original index
for (int j = 0; j < childrenCount; j++) {
if (children[childIndex] == mChildren[j]) {
mLastTouchDownIndex = j;
break;
}
}
} else {
mLastTouchDownIndex = childIndex;
}
//最后触摸的位置
mLastTouchDownX = ev.getX();
mLastTouchDownY = ev.getY();
//添加事件目标
newTouchTarget = addTouchTarget(child, idBitsToAssign);
alreadyDispatchedToNewTouchTarget = true;
break;
}
// The accessibility focus didn't handle the event, so clear
// the flag and do a normal dispatch to all children.
ev.setTargetAccessibilityFocus(false);
}
if (preorderedList != null) preorderedList.clear();
}
if (newTouchTarget == null && mFirstTouchTarget != null) {
// Did not find a child to receive the event.
// Assign the pointer to the least recently added target.
newTouchTarget = mFirstTouchTarget;
while (newTouchTarget.next != null) {
newTouchTarget = newTouchTarget.next;
}
newTouchTarget.pointerIdBits |= idBitsToAssign;
}
}
}
//事件分发目标
// Dispatch to touch targets.
if (mFirstTouchTarget == null) {
//第一次 或者处理完一次后事件分发目标肯定是null的
// No touch targets so treat this as an ordinary view.
handled = dispatchTransformedTouchEvent(ev, canceled, null,
TouchTarget.ALL_POINTER_IDS);
} else {
// Dispatch to touch targets, excluding the new touch target if we already
// dispatched to it. Cancel touch targets if necessary.
TouchTarget predecessor = null;
TouchTarget target = mFirstTouchTarget;
while (target != null) {
final TouchTarget next = target.next;
if (alreadyDispatchedToNewTouchTarget && target == newTouchTarget) {
handled = true;
} else {
final boolean cancelChild = resetCancelNextUpFlag(target.child)
|| intercepted;
if (dispatchTransformedTouchEvent(ev, cancelChild,
target.child, target.pointerIdBits)) {
handled = true;
}
if (cancelChild) {
if (predecessor == null) {
mFirstTouchTarget = next;
} else {
predecessor.next = next;
}
target.recycle();
target = next;
continue;
}
}
predecessor = target;
target = next;
}
}
// Update list of touch targets for pointer up or cancel, if needed.
if (canceled
|| actionMasked == MotionEvent.ACTION_UP
|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
resetTouchState();
} else if (split && actionMasked == MotionEvent.ACTION_POINTER_UP) {
final int actionIndex = ev.getActionIndex();
final int idBitsToRemove = 1 << ev.getPointerId(actionIndex);
removePointersFromTouchTargets(idBitsToRemove);
}
}
if (!handled && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(ev, 1);
}
return handled;
}
在执行事件分发逻辑时，ViewGroup会去判断是否要对View进行事件拦截，如果进行了拦截，就没有后面View的事件分发和处理了，
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (ev.isFromSource(InputDevice.SOURCE_MOUSE)
&& ev.getAction() == MotionEvent.ACTION_DOWN
&& ev.isButtonPressed(MotionEvent.BUTTON_PRIMARY)
&& isOnScrollbarThumb(ev.getX(), ev.getY())) {
return true;
}
return false;
}
事件拦截默认返回false，是不拦截的，如果需要拦截view的事件，在对应的布局容器中重写onInterceptTouchEvent返回true，如果事件没有被取消，也没有被拦截，第一次mFirstTouchTarget肯定是null的，就会调用
handled = dispatchTransformedTouchEvent(ev, canceled, null,TouchTarget.ALL_POINTER_IDS);
mFirstTouchTarget是一个TouchTarget实例对象，是用于描述和存储事件目标view的，使用的是单项链表的结构，
private boolean dispatchTransformedTouchEvent(MotionEvent event, boolean cancel,
View child, int desiredPointerIdBits) {
final boolean handled;
// Canceling motions is a special case. We don't need to perform any transformations
// or filtering. The important part is the action, not the contents.
final int oldAction = event.getAction();
if (cancel || oldAction == MotionEvent.ACTION_CANCEL) {
//如果是事件取消的话 设置事件的类型
event.setAction(MotionEvent.ACTION_CANCEL);
if (child == null) {
//view为null 直接调用ViewGroup的父类的事件分发
handled = super.dispatchTouchEvent(event);
} else {
//调用view child的事件分发
handled = child.dispatchTouchEvent(event);
}
event.setAction(oldAction);
//将分发结果返回
return handled;
}
// Calculate the number of pointers to deliver.
final int oldPointerIdBits = event.getPointerIdBits();
final int newPointerIdBits = oldPointerIdBits & desiredPointerIdBits;
// If for some reason we ended up in an inconsistent state where it looks like we
// might produce a motion event with no pointers in it, then drop the event.
if (newPointerIdBits == 0) {
return false;
}
// If the number of pointers is the same and we don't need to perform any fancy
// irreversible transformations, then we can reuse the motion event for this
// dispatch as long as we are careful to revert any changes we make.
// Otherwise we need to make a copy.
final MotionEvent transformedEvent;
if (newPointerIdBits == oldPointerIdBits) {
if (child == null || child.hasIdentityMatrix()) {
if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
//计算view事件的坐标
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
event.offsetLocation(offsetX, offsetY);
handled = child.dispatchTouchEvent(event);
event.offsetLocation(-offsetX, -offsetY);
}
return handled;
}
transformedEvent = MotionEvent.obtain(event);
} else {
transformedEvent = event.split(newPointerIdBits);
}
// Perform any necessary transformations and dispatch.
if (child == null) {
//第一次的时候child肯定是null的
handled = super.dispatchTouchEvent(transformedEvent);
} else {
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
transformedEvent.offsetLocation(offsetX, offsetY);
if (! child.hasIdentityMatrix()) {
transformedEvent.transform(child.getInverseMatrix());
}
handled = child.dispatchTouchEvent(transformedEvent);
}
// Done.
transformedEvent.recycle();
return handled;
}
看到最终会交互view或者ViewGroup的父类的dispatchTouchEvent去进行事件分发的处理，
public boolean dispatchTouchEvent(MotionEvent event) {
// If the event should be handled by accessibility focus first.
if (event.isTargetAccessibilityFocus()) {
// We don't have focus or no virtual descendant has it, do not handle the event.
if (!isAccessibilityFocusedViewOrHost()) {
return false;
}
// We have focus and got the event, then use normal event dispatch.
event.setTargetAccessibilityFocus(false);
}
//定义事件分发的结果标识
boolean result = false;
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}
final int actionMasked = event.getActionMasked();
if (actionMasked == MotionEvent.ACTION_DOWN) {
// Defensive cleanup for new gesture
//停止正在的滚动
stopNestedScroll();
}
if (onFilterTouchEventForSecurity(event)) {
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
result = true;
}
//noinspection SimplifiableIfStatement
//监听触摸等的实例对象
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
//代表对该事件进行了消费
result = true;
}
//如果result为false 会通过onTouchEvent看看对该事件有没有进行消费
if (!result && onTouchEvent(event)) {
result = true;
}
}
if (!result && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
// Clean up after nested scrolls if this is the end of a gesture;
// also cancel it if we tried an ACTION_DOWN but we didn't want the rest
// of the gesture.
if (actionMasked == MotionEvent.ACTION_UP ||
actionMasked == MotionEvent.ACTION_CANCEL ||
(actionMasked == MotionEvent.ACTION_DOWN && !result)) {
stopNestedScroll();
}
return result;
}
ListenerInfo是一个静态的管理一些了事件监听的类，其中就包含了OnTouchListener，可以给对应的View或者ViewGroup设置OnTouchListener来达到事件消费的目的，
findViewById(R.id.view_id).setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
//默认返回false 改为返回true 代表消费当前事件
return true;
}
});
如果并没有设置OnTouchListener就会通过onTouchEvent看看有没有对该事件进行消费，
public boolean onTouchEvent(MotionEvent event) {
//获取事件的范围
final float x = event.getX();
final float y = event.getY();
final int viewFlags = mViewFlags;
//获取事件的类型
final int action = event.getAction();
//是否是可点击的
final boolean clickable = ((viewFlags & CLICKABLE) == CLICKABLE
|| (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)
|| (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE;
if ((viewFlags & ENABLED_MASK) == DISABLED) {
if (action == MotionEvent.ACTION_UP && (mPrivateFlags & PFLAG_PRESSED) != 0) {
setPressed(false);
}
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
// A disabled view that is clickable still consumes the touch
// events, it just doesn't respond to them.
return clickable;
}
if (mTouchDelegate != null) {
if (mTouchDelegate.onTouchEvent(event)) {
return true;
}
}
if (clickable || (viewFlags & TOOLTIP) == TOOLTIP) {
switch (action) {
case MotionEvent.ACTION_UP:
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
if ((viewFlags & TOOLTIP) == TOOLTIP) {
handleTooltipUp();
}
if (!clickable) {
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
break;
}
boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
// take focus if we don't have it already and we should in
// touch mode.
boolean focusTaken = false;
if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
focusTaken = requestFocus();
}
if (prepressed) {
// The button is being released before we actually
// showed it as pressed. Make it show the pressed
// state now (before scheduling the click) to ensure
// the user sees it.
setPressed(true, x, y);
}
if (!mHasPerformedLongPress && !mIgnoreNextUpEvent) {
// This is a tap, so remove the longpress check
removeLongPressCallback();
// Only perform take click actions if we were in the pressed state
if (!focusTaken) {
// Use a Runnable and post this rather than calling
// performClick directly. This lets other visual state
// of the view update before click actions start.
//创建PerformClick实例
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
if (!post(mPerformClick)) {
//调用该方法通过点击事件的触发来进行事件的消费
performClickInternal();
}
}
}
if (mUnsetPressedState == null) {
mUnsetPressedState = new UnsetPressedState();
}
if (prepressed) {
postDelayed(mUnsetPressedState,
ViewConfiguration.getPressedStateDuration());
} else if (!post(mUnsetPressedState)) {
// If the post failed, unpress right now
mUnsetPressedState.run();
}
removeTapCallback();
}
mIgnoreNextUpEvent = false;
break;
case MotionEvent.ACTION_DOWN:
if (event.getSource() == InputDevice.SOURCE_TOUCHSCREEN) {
mPrivateFlags3 |= PFLAG3_FINGER_DOWN;
}
mHasPerformedLongPress = false;
if (!clickable) {
checkForLongClick(
ViewConfiguration.getLongPressTimeout(),
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__LONG_PRESS);
break;
}
if (performButtonActionOnTouchDown(event)) {
break;
}
// Walk up the hierarchy to determine if we're inside a scrolling container.
boolean isInScrollingContainer = isInScrollingContainer();
// For views inside a scrolling container, delay the pressed feedback for
// a short period in case this is a scroll.
if (isInScrollingContainer) {
mPrivateFlags |= PFLAG_PREPRESSED;
if (mPendingCheckForTap == null) {
mPendingCheckForTap = new CheckForTap();
}
mPendingCheckForTap.x = event.getX();
mPendingCheckForTap.y = event.getY();
postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
} else {
// Not inside a scrolling container, so show the feedback right away
setPressed(true, x, y);
checkForLongClick(
ViewConfiguration.getLongPressTimeout(),
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__LONG_PRESS);
}
break;
case MotionEvent.ACTION_CANCEL:
if (clickable) {
setPressed(false);
}
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
break;
case MotionEvent.ACTION_MOVE:
if (clickable) {
drawableHotspotChanged(x, y);
}
final int motionClassification = event.getClassification();
final boolean ambiguousGesture =
motionClassification == MotionEvent.CLASSIFICATION_AMBIGUOUS_GESTURE;
int touchSlop = mTouchSlop;
if (ambiguousGesture && hasPendingLongPressCallback()) {
if (!pointInView(x, y, touchSlop)) {
// The default action here is to cancel long press. But instead, we
// just extend the timeout here, in case the classification
// stays ambiguous.
removeLongPressCallback();
long delay = (long) (ViewConfiguration.getLongPressTimeout()
* mAmbiguousGestureMultiplier);
// Subtract the time already spent
delay -= event.getEventTime() - event.getDownTime();
checkForLongClick(
delay,
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__LONG_PRESS);
}
touchSlop *= mAmbiguousGestureMultiplier;
}
// Be lenient about moving outside of buttons
if (!pointInView(x, y, touchSlop)) {
// Outside button
// Remove any future long press/tap checks
removeTapCallback();
removeLongPressCallback();
if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
setPressed(false);
}
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
}
final boolean deepPress =
motionClassification == MotionEvent.CLASSIFICATION_DEEP_PRESS;
if (deepPress && hasPendingLongPressCallback()) {
// process the long click action immediately
removeLongPressCallback();
checkForLongClick(
0 /* send immediately */,
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__DEEP_PRESS);
}
break;
}
return true;
}
return false;
}
当事件类型为ACTION_UP的时候就会创建一个PerformClick实例对象，并调用performClickInternal方法通过click点击方式来消费该事件，
public boolean performClick() {
// We still need to call this method to handle the cases where performClick() was called
// externally, instead of through performClickInternal()
notifyAutofillManagerOnClick();
final boolean result;
final ListenerInfo li = mListenerInfo;
if (li != null && li.mOnClickListener != null) {
playSoundEffect(SoundEffectConstants.CLICK);
li.mOnClickListener.onClick(this);
result = true;
} else {
result = false;
}
sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
notifyEnterOrExitForAutoFillIfNeeded(true);
return result;
}
这里就会我们平时通过setOnClickListener点击事件，然后重写onClick方法方式去消费对应的点击事件，上面是TouchTarget为null且child为null的情况，如果childCount不为0的时候，在按下的时候会从前到后一次遍历每个view，同时获取对应的TouchTarget，
private TouchTarget getTouchTarget(@NonNull View child) {
for (TouchTarget target = mFirstTouchTarget; target != null; target = target.next) {
if (target.child == child) {
return target;
}
}
return null;
}
如果转换得到的view有对应的事件要处理，会添加绑定对应的TouchTarget，
private TouchTarget addTouchTarget(@NonNull View child, int pointerIdBits) {
final TouchTarget target = TouchTarget.obtain(child, pointerIdBits);
target.next = mFirstTouchTarget;
mFirstTouchTarget = target;
return target;
}
这样子一直到事件被消费处理掉。
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