细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
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文章转自:http://blog.csdn.net/yanzi1225627/article/details/22592831
作者:yanzi1225627
本文背景:前些天用到了之前写的自定义图片文字复合控件,在给他设置监听时遇到了麻烦。虽然最后解决了问题,但发现在不重写LinearLayout的onInterceptTouchEvent时,子ImageView、子TextView、父Linearlayout三者不同的属性配置(android:clickable android:focuseable)会造成自定义控件onClick监听失败、或成功。复写了父Linearlayout 的onInterceptTouchEvent时,监听不受子图片、子文字的属性影响。为知其所以然,深入研究android的事件传递机制,记录于此。
一、View的dispatchTouchEvent和onTouchEvent
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Log.i(tag, "testLinelayout---onClick...");
}
});
@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
return false;
}
});
- <span style="font-size:18px;"> /**
- * Pass the touch screen motion event down to the target view, or this
- * view if it is the target.
- *
- * @param event The motion event to be dispatched.
- * @return True if the event was handled by the view, false otherwise.
- */
- public boolean dispatchTouchEvent(MotionEvent event) {
- if (mInputEventConsistencyVerifier != null) {
- mInputEventConsistencyVerifier.onTouchEvent(event, 0);
- }
- if (onFilterTouchEventForSecurity(event)) {
- //noinspection SimplifiableIfStatement
- ListenerInfo li = mListenerInfo;
- if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
- && li.mOnTouchListener.onTouch(this, event)) {
- return true;
- }
- if (onTouchEvent(event)) {
- return true;
- }
- }
- if (mInputEventConsistencyVerifier != null) {
- mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
- }
- return false;
- }</span>
&& li.mOnTouchListener.onTouch(this, event)) {
return true;
}
- <span style="font-size:18px;"> if (onTouchEvent(event)) {
- return true;
- }</span>
- <span style="font-size:18px;"> if (!mHasPerformedLongPress) {
- // 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.
- if (mPerformClick == null) {
- mPerformClick = new PerformClick();
- }
- if (!post(mPerformClick)) {
- <span style="color:#ff0000;"> performClick();</span>
- }
- }
- }</span>
- <span style="font-size:18px;"> public boolean performClick() {
- sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
- ListenerInfo li = mListenerInfo;
- if (li != null && li.mOnClickListener != null) {
- playSoundEffect(SoundEffectConstants.CLICK);
- <span style="color:#ff0000;"><strong>li.mOnClickListener.onClick(this);</strong></span>
- return true;
- }
- return false;
- }</span>
终于对上了,它执行了我们注册的onClick监听。当然执行前会经过一系列判断,是否注册了监听等。
总结:
- <span style="font-size:18px;">package org.yanzi.ui;
- import android.content.Context;
- import android.util.AttributeSet;
- import android.util.Log;
- import android.view.MotionEvent;
- import android.widget.Button;
- public class TestButton extends Button {
- private final static String tag = "yan";
- public TestButton(Context context, AttributeSet attrs) {
- super(context, attrs);
- // TODO Auto-generated constructor stub
- }
- @Override
- public boolean onTouchEvent(MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "TestButton-onTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "TestButton-onTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.onTouchEvent(event);
- }
- @Override
- public boolean dispatchTouchEvent(MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "TestButton-dispatchTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "TestButton-dispatchTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.dispatchTouchEvent(event);
- }
- }
- </span>
在Activity里注册两个监听:
- <span style="font-size:18px;"> testBtn.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View v) {
- // TODO Auto-generated method stub
- Log.i(tag, "testBtn---onClick...");
- }
- });
- testBtn.setOnTouchListener(new View.OnTouchListener() {
- @Override
- public boolean onTouch(View v, MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "testBtn-onTouch-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "testBtn-onTouch-ACTION_UP...");
- break;
- default:break;
- }
- return false;
- }
- });</span>
同时复写Activity的dispatch方法和onTouchEvent方法:
- <span style="font-size:18px;">@Override
- public boolean dispatchTouchEvent(MotionEvent ev) {
- // TODO Auto-generated method stub
- switch(ev.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "MainActivity-dispatchTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "MainActivity-dispatchTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.dispatchTouchEvent(ev);
- }
- @Override
- public boolean onTouchEvent(MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "MainActivity-onTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "MainActivity-onTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.onTouchEvent(event);
- }</span>
最终一次点击,打印信息如下:
Line 35: 01-08 14:59:45.849 I/yan ( 4613): TestButton-dispatchTouchEvent-ACTION_DOWN...
Line 37: 01-08 14:59:45.849 I/yan ( 4613): testBtn-onTouch-ACTION_DOWN...
Line 39: 01-08 14:59:45.849 I/yan ( 4613): TestButton-onTouchEvent-ACTION_DOWN...
Line 41: 01-08 14:59:45.939 I/yan ( 4613): MainActivity-dispatchTouchEvent-ACTION_UP...
Line 43: 01-08 14:59:45.941 I/yan ( 4613): TestButton-dispatchTouchEvent-ACTION_UP...
Line 45: 01-08 14:59:45.944 I/yan ( 4613): testBtn-onTouch-ACTION_UP...
Line 47: 01-08 14:59:45.946 I/yan ( 4613): TestButton-onTouchEvent-ACTION_UP...
Line 49: 01-08 14:59:45.974 I/yan ( 4613): testBtn---onClick...
- <span style="font-size:18px;">testBtn.setOnTouchListener(new View.OnTouchListener() {
- @Override
- public boolean onTouch(View v, MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "testBtn-onTouch-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "testBtn-onTouch-ACTION_UP...");
- break;
- default:break;
- }
- return true;
- }
- });</span>
事件流程为:
Line 77: 01-08 15:05:51.628 I/yan ( 5262): TestButton-dispatchTouchEvent-ACTION_DOWN...
Line 79: 01-08 15:05:51.629 I/yan ( 5262): testBtn-onTouch-ACTION_DOWN...
Line 81: 01-08 15:05:51.689 I/yan ( 5262): MainActivity-dispatchTouchEvent-ACTION_UP...
Line 83: 01-08 15:05:51.691 I/yan ( 5262): TestButton-dispatchTouchEvent-ACTION_UP...
Line 85: 01-08 15:05:51.695 I/yan ( 5262): testBtn-onTouch-ACTION_UP...
二、ViewGroup的dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent
- <span style="font-size:18px;"> public boolean dispatchTouchEvent(MotionEvent ev) {
- if (mInputEventConsistencyVerifier != null) {
- mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
- }
- boolean handled = false;
- if (onFilterTouchEventForSecurity(ev)) {
- final int action = ev.getAction();
- 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.
- cancelAndClearTouchTargets(ev);
- resetTouchState();
- }
- // Check for interception.
- final boolean intercepted;
- if (actionMasked == MotionEvent.ACTION_DOWN
- || mFirstTouchTarget != null) {
- final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
- if (!disallowIntercept) {
- <strong><span style="color:#ff0000;">intercepted = onInterceptTouchEvent(ev);</span></strong>
- 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.
- intercepted = true;
- }
- // Check for cancelation.
- final boolean canceled = resetCancelNextUpFlag(this)
- || actionMasked == MotionEvent.ACTION_CANCEL;
- // Update list of touch targets for pointer down, if needed.
- final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0;
- TouchTarget newTouchTarget = null;
- boolean alreadyDispatchedToNewTouchTarget = false;
- <strong><span style="color:#ff0000;">if (!canceled && !intercepted)</span></strong> {
- 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);
- final int childrenCount = mChildrenCount;
- if (childrenCount != 0) {
- // Find a child that can receive the event.
- // Scan children from front to back.
- final View[] children = mChildren;
- final float x = ev.getX(actionIndex);
- final float y = ev.getY(actionIndex);
- final boolean customOrder = isChildrenDrawingOrderEnabled();
- for (int i = childrenCount - 1; i >= 0; i--) {
- final int childIndex = customOrder ?
- getChildDrawingOrder(childrenCount, i) : i;
- final View child = children[childIndex];
- if (!canViewReceivePointerEvents(child)
- || !isTransformedTouchPointInView(x, y, child, null)) {
- continue;
- }
- 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;
- }
- resetCancelNextUpFlag(child);
- if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
- // Child wants to receive touch within its bounds.
- mLastTouchDownTime = ev.getDownTime();
- mLastTouchDownIndex = childIndex;
- mLastTouchDownX = ev.getX();
- mLastTouchDownY = ev.getY();
- newTouchTarget = addTouchTarget(child, idBitsToAssign);
- alreadyDispatchedToNewTouchTarget = true;
- break;
- }
- }
- }
- 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;
- }
- }
- }
- // Dispatch to touch targets.
- if (mFirstTouchTarget == null) {
- // 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;
- }</span>
可以看到标红的有两句(intercepted = onInterceptTouchEvent(ev); if (!canceled && !intercepted) ),它会先调用 intercepted = onInterceptTouchEvent(ev);然后通过if判断。
- <span style="font-size:18px;"> public boolean onInterceptTouchEvent(MotionEvent ev) {
- return false;
- }</span>
它就一句话,默认false。也就是说这个谋士默认的意见是,永远不拦截!!!!只要有孩子,就交给孩子们处理吧。下面给出实例说明,新建TestLinearLayout继承自Linearlayout。
- <span style="font-size:18px;">package org.yanzi.ui;
- import android.content.Context;
- import android.util.AttributeSet;
- import android.util.Log;
- import android.view.MotionEvent;
- import android.widget.LinearLayout;
- public class TestLinearLayout extends LinearLayout{
- private final static String tag = "yan";
- public TestLinearLayout(Context context, AttributeSet attrs) {
- super(context, attrs);
- // TODO Auto-generated constructor stub
- }
- @Override
- public boolean dispatchTouchEvent(MotionEvent ev) {
- // TODO Auto-generated method stub
- switch(ev.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "TestLinearLayout-dispatchTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "TestLinearLayout-dispatchTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.dispatchTouchEvent(ev);
- }
- @Override
- public boolean onInterceptTouchEvent(MotionEvent ev) {
- // TODO Auto-generated method stub
- switch(ev.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "TestLinearLayout-onInterceptTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "TestLinearLayout-onInterceptTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.onInterceptTouchEvent(ev);
- }
- @Override
- public boolean onTouchEvent(MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "TestLinearLayout-onTouchEvent-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "TestLinearLayout-onTouchEvent-ACTION_UP...");
- break;
- default:break;
- }
- return super.onTouchEvent(event);
- }
- }
- </span>
- <span style="font-size:18px;"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- android:layout_width="match_parent"
- android:layout_height="match_parent"
- android:paddingBottom="@dimen/activity_vertical_margin"
- android:paddingLeft="@dimen/activity_horizontal_margin"
- android:paddingRight="@dimen/activity_horizontal_margin"
- android:paddingTop="@dimen/activity_vertical_margin"
- tools:context=".MainActivity" >
- <TextView
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="@string/hello_world" />
- <org.yanzi.ui.TestLinearLayout
- android:id="@+id/linearlayout_test"
- android:layout_width="200dip"
- android:layout_height="200dip" >
- <org.yanzi.ui.TestButton
- android:id="@+id/btn_test"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="测试按钮" />
- </org.yanzi.ui.TestLinearLayout>
- </RelativeLayout></span>
在Activity里给这个自定义LinearLayout也注册上onClick监听、onTouch监听。
- <span style="font-size:18px;">testLinelayout = (TestLinearLayout)findViewById(R.id.linearlayout_test);
- testLinelayout.setOnTouchListener(new View.OnTouchListener() {
- @Override
- public boolean onTouch(View v, MotionEvent event) {
- // TODO Auto-generated method stub
- switch(event.getAction()){
- case MotionEvent.ACTION_DOWN:
- Log.i(tag, "testLinelayout-onTouch-ACTION_DOWN...");
- break;
- case MotionEvent.ACTION_UP:
- Log.i(tag, "testLinelayout-onTouch-ACTION_UP...");
- break;
- default:break;
- }
- return false;
- }
- });
- testLinelayout.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View v) {
- // TODO Auto-generated method stub
- Log.i(tag, "testLinelayout---onClick...");
- }
- });</span>
不复写事件传递里的 任何方法,流程如下:
Line 59: 01-08 15:29:42.169 I/yan ( 5826): TestLinearLayout-dispatchTouchEvent-ACTION_DOWN...
Line 61: 01-08 15:29:42.169 I/yan ( 5826): TestLinearLayout-onInterceptTouchEvent-ACTION_DOWN...
Line 63: 01-08 15:29:42.169 I/yan ( 5826): TestButton-dispatchTouchEvent-ACTION_DOWN...
Line 65: 01-08 15:29:42.170 I/yan ( 5826): testBtn-onTouch-ACTION_DOWN...
Line 67: 01-08 15:29:42.170 I/yan ( 5826): TestButton-onTouchEvent-ACTION_DOWN...
Line 69: 01-08 15:29:42.279 I/yan ( 5826): MainActivity-dispatchTouchEvent-ACTION_UP...
Line 71: 01-08 15:29:42.280 I/yan ( 5826): TestLinearLayout-dispatchTouchEvent-ACTION_UP...
Line 73: 01-08 15:29:42.283 I/yan ( 5826): TestLinearLayout-onInterceptTouchEvent-ACTION_UP...
Line 75: 01-08 15:29:42.287 I/yan ( 5826): TestButton-dispatchTouchEvent-ACTION_UP...
Line 81: 01-08 15:29:42.298 I/yan ( 5826): testBtn-onTouch-ACTION_UP...
Line 83: 01-08 15:29:42.301 I/yan ( 5826): TestButton-onTouchEvent-ACTION_UP...
Line 85: 01-08 15:29:42.313 I/yan ( 5826): testBtn---onClick...
Line 133: 01-08 15:36:16.574 I/yan ( 6124): TestLinearLayout-onInterceptTouchEvent-ACTION_DOWN...
Line 135: 01-08 15:36:16.574 I/yan ( 6124): TestButton-dispatchTouchEvent-ACTION_DOWN...
Line 137: 01-08 15:36:16.575 I/yan ( 6124): TestButton-onTouchEvent-ACTION_DOWN...
Line 143: 01-08 15:36:16.746 I/yan ( 6124): MainActivity-dispatchTouchEvent-ACTION_UP...
Line 145: 01-08 15:36:16.747 I/yan ( 6124): TestLinearLayout-dispatchTouchEvent-ACTION_UP...
Line 147: 01-08 15:36:16.747 I/yan ( 6124): TestLinearLayout-onInterceptTouchEvent-ACTION_UP...
Line 149: 01-08 15:36:16.748 I/yan ( 6124): TestButton-dispatchTouchEvent-ACTION_UP...
Line 151: 01-08 15:36:16.748 I/yan ( 6124): TestButton-onTouchEvent-ACTION_UP...
Line 59: 01-08 15:40:06.835 I/yan ( 6640): TestLinearLayout-dispatchTouchEvent-ACTION_DOWN...
Line 61: 01-08 15:40:06.836 I/yan ( 6640): TestLinearLayout-onInterceptTouchEvent-ACTION_DOWN...
Line 63: 01-08 15:40:06.836 I/yan ( 6640): testLinelayout-onTouch-ACTION_DOWN...
Line 65: 01-08 15:40:06.836 I/yan ( 6640): TestLinearLayout-onTouchEvent-ACTION_DOWN...
Line 67: 01-08 15:40:07.016 I/yan ( 6640): MainActivity-dispatchTouchEvent-ACTION_UP...
Line 69: 01-08 15:40:07.017 I/yan ( 6640): TestLinearLayout-dispatchTouchEvent-ACTION_UP...
Line 73: 01-08 15:40:07.025 I/yan ( 6640): testLinelayout-onTouch-ACTION_UP...
Line 75: 01-08 15:40:07.026 I/yan ( 6640): TestLinearLayout-onTouchEvent-ACTION_UP...
Line 77: 01-08 15:40:07.052 I/yan ( 6640): testLinelayout---onClick...
public boolean onTouchEvent(MotionEvent event) {return super.onTouchEvent(event);}
public boolean dispatchTouchEvent(MotionEvent event) {return super.dispatchTouchEvent(event);
1、Android事件构成
l 在Android中,事件主要包括点按、长按、拖拽、滑动等,点按又包括单击和双击,另外还包括单指操作和多指操作。所有这些都构成了Android中得事件响应。总的来说,所有的事件都由如下三个部分作为基础:
按下(ACTION_DOWN)
移动(ACTION_MOVE)
抬起(ACTION_UP)
l 所有的操作事件首先必须执行的是按下操作(ACTION_DOWN),之后所有的操作都是以按下操作作为前提,当按下操作完成后,接下来可能是一段移动(ACTION_MOVE)然后抬起(ACTION_UP),或者是按下操作执行完成后没有移动就直接抬起。这一系列的动作在Android中都可以进行控制。
2、
l Android中事件传递按照从上到下进行层级传递,事件处理从Activity开始到ViewGroup再到View。
l Activity 不是View也不是ViewGroup,只有dispatchTouchEvent和onTouchEvent两个方法,Activity的dispatchTouchEvent,这个是表层的Touch的第一入口。
l 事件传递方法包括dispatchTouchEvent、onTouchEvent、onInterceptTouchEvent,其中前两个是View和ViewGroup都有的,最后一个是只有ViewGroup才有的方法。这三个方法的作用分别是负责事件分发、事件处理、事件拦截。
l onTouch事件要先于onClick事件执行,onTouch在事件分发方法dispatchTouchEvent中调用,而onClick在事件处理方法onTouchEvent中被调用,onTouchEvent要后于dispatchTouchEvent方法的调用。
3、
l ViewGroup里的onInterceptTouchEvent默认值是false这样才能把事件传给View里的onTouchEvent。
l ViewGroup里的onTouchEvent默认值是false。
l View里的onTouchEvent返回默认值是true.这样才能执行多次touch事件。所以默认情况下事件将在最终的view 中被消费。如果最终需要处理事件的view的onTouchEvent()返回了false,那么该事件将被传递至其上一层次的view的onTouchEvent()处理。
4、
l ACTION_MOVE或者ACTION_UP发生的前提是一定曾经发生了ACTION_DOWN,如果你没有消费ACTION_DOWN,那么系统会认为ACTION_DOWN没有发生过,所以ACTION_MOVE或者ACTION_UP就不能被捕获。
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
- 细说Android事件传递机制(dispatchTouchEvent、onInterceptTouchEvent、onTouchEvent)
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