- 首先我们上我们的测试代码
public class MyButton extends Button {
public MyButton(Context context) {
super(context);
}
public MyButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyButton(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action)
{
case MotionEvent.ACTION_DOWN:
Log.e("MyButton", "dispatchTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e("MyButton", "dispatchTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e("MyButton", "dispatchTouchEvent ACTION_UP");
break;
default:
break;
}
boolean b = super.dispatchTouchEvent(event);
Log.e("MyButton", "dispatchTouchEvent==="+b);
return b;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action)
{
case MotionEvent.ACTION_DOWN:
Log.e("MyButton", "onTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e("MyButton", "onTouchEvent ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e("MyButton", "onTouchEvent ACTION_UP");
break;
default:
break;
}
boolean b = super.onTouchEvent(event);
Log.e("MyButton", "onTouchEvent==="+b);
return b;
}
}
- activity中的测试代码
//测试事件传递
public class TestEventActivity extends AppCompatActivity {
@Bind(R.id.toolbar)
Toolbar toolbar;
@Bind(R.id.bt_event)
MyButton mBtEvent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_event);
ButterKnife.bind(this);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mBtEvent.setOnTouchListener(new View.OnTouchListener()
{
@Override
public boolean onTouch(View v, MotionEvent event)
{
int action = event.getAction();
switch (action)
{
case MotionEvent.ACTION_DOWN:
Log.e("mBtEvent", "onTouch ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e("mBtEvent", "onTouch ACTION_MOVE");
break;
case MotionEvent.ACTION_UP:
Log.e("mBtEvent", "onTouch ACTION_UP");
break;
default:
break;
}
return false;
}
});
}
}
-
我们运行看下日志
12-02 11:37:33.901 15256-15256/? E/MyButton: dispatchTouchEvent ACTION_DOWN 12-02 11:37:33.903 15256-15256/? E/mBtEvent: onTouch ACTION_DOWN 12-02 11:37:33.904 15256-15256/? E/MyButton: onTouchEvent ACTION_DOWN 12-02 11:37:33.905 15256-15256/? E/MyButton: onTouchEvent===true 12-02 11:37:33.906 15256-15256/? E/MyButton: dispatchTouchEvent===true 12-02 11:37:33.975 15256-15256/? E/MyButton: dispatchTouchEvent ACTION_UP 12-02 11:37:33.977 15256-15256/? E/mBtEvent: onTouch ACTION_UP 12-02 11:37:33.977 15256-15256/? E/MyButton: onTouchEvent ACTION_UP 12-02 11:37:33.978 15256-15256/? E/MyButton: onTouchEvent===true 12-02 11:37:33.978 15256-15256/? E/MyButton: dispatchTouchEvent===true
可以看到我们运行之后有down和up的时候传递的过程是一样的： dispatchTouchEvent-onTouch-onTouchEvent 这个里面我们得出的结论是activity里面的onTouch事件要优先于onTouchEvent执行！
-
我们跟进首先执行的dispatchTouchEvent的源码看下:
public boolean dispatchTouchEvent(MotionEvent event) { if (!onFilterTouchEventForSecurity(event)) { return false; } if (mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED && mOnTouchListener.onTouch(this, event)) { return true; } return onTouchEvent(event); } 我们看到这个是主要的分发逻辑，大概的意思： 1.首先判断有没有设置mOnTouchListener 2.我们的控件是不是可点击的ENABLED 3.判断mOnTouchListener设置的返回值 ------------------------------------------------------- 假如上面都成立那么就不会调用onTouchEvent，简单来说就是我们的activity中的onTouch返回true就回倒置onTouchEvent不会执行！ -
接下来是view的onTouchEvent的源码
/**
* Implement this method to handle touch screen motion events.
*
* @param event The motion event.
* @return True if the event was handled, false otherwise.
*/
public boolean onTouchEvent(MotionEvent event) {
final int viewFlags = mViewFlags;
//当前的控件是不可点击的
if ((viewFlags & ENABLED_MASK) == DISABLED) {
// A disabled view that is clickable still consumes the touch
// events, it just doesn't respond to them.
return (((viewFlags & CLICKABLE) == CLICKABLE ||
(viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE));
}
if (mTouchDelegate != null) {
if (mTouchDelegate.onTouchEvent(event)) {
return true;
}
}
//当前的控件只是点击的，或者是长按事件就会就走到里面最终一定return true
if (((viewFlags & CLICKABLE) == CLICKABLE ||
(viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)) {
switch (event.getAction()) {
case MotionEvent.ACTION_UP:
boolean prepressed = (mPrivateFlags & PREPRESSED) != 0;
if ((mPrivateFlags & 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();
}
//如果长按事件被调用则这个数值会被设置为true，否则为false
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)) {
//调用view的click事件
performClick();
}
}
}
if (mUnsetPressedState == null) {
mUnsetPressedState = new UnsetPressedState();
}
if (prepressed) {
mPrivateFlags |= PRESSED;
refreshDrawableState();
postDelayed(mUnsetPressedState,
ViewConfiguration.getPressedStateDuration());
} else if (!post(mUnsetPressedState)) {
// If the post failed, unpress right now
mUnsetPressedState.run();
}
removeTapCallback();
}
break;
case MotionEvent.ACTION_DOWN:
if (mPendingCheckForTap == null) {
mPendingCheckForTap = new CheckForTap();
}
//给mPrivateFlags设置一个PREPRESSED的标识
mPrivateFlags |= PREPRESSED;
//表示长按事件还未触发；
mHasPerformedLongPress = false;
//发送一个延时为115毫秒它是由一个常量定义的mPendingCheckForTap就是一个继承的Runnable的类，在这个里面进行长按事件的判断，如果达到执行长按事件的条件就或执行长按事件的方法！
postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
break;
case MotionEvent.ACTION_CANCEL:
mPrivateFlags &= ~PRESSED;
refreshDrawableState();
removeTapCallback();
break;
//总结一下：只要用户移出了我们的控件：则将mPrivateFlags取出PRESSED标识，且移除所有在DOWN中设置的检测，长按等；
case MotionEvent.ACTION_MOVE:
//拿到当前触摸的x,y坐标
final int x = (int) event.getX();
final int y = (int) event.getY();
// Be lenient about moving outside of buttons
//判断当然触摸点有没有移出我们的View如果出去了就移除长按的检查mPrivateFlags中PRESSED标识去除，刷新背景
int slop = mTouchSlop;
if ((x < 0 - slop) || (x >= getWidth() + slop) ||
(y < 0 - slop) || (y >= getHeight() + slop)) {
// Outside button
removeTapCallback();
if ((mPrivateFlags & PRESSED) != 0) {
// Remove any future long press/tap checks
removeLongPressCallback();
// Need to switch from pressed to not pressed
mPrivateFlags &= ~PRESSED;
refreshDrawableState();
}
}
break;
}
return true;
}
return false;
}
##总结
1.整个view的分发流程是 View.dispatchEvent->View.setOnTouchListener->View.onTouchEvent
2.在dispatchEvent会进行判断当前的view有没有设置setOnTouchListener和返回是不是true，并且是不是可点击的，如果都成立onTouchEvent就不会执行！
### DOWN
a、首先设置标志为PREPRESSED，设置mHasPerformedLongPress=false;,这个标记我们从代码综合那个可以看出就是来进行判断是否执行过了longclick事件，如果执行过了就要remove，然后发出一个115ms后的mPendingCheckForTap；
b、如果115ms内没有触发UP，则将标志置为PRESSED，清除PREPRESSED标志，同时发出一个延时为500-115ms的，检测长按任务消息；
c、如果500ms内（从DOWN触发开始算），则会触发LongClickListener:
此时如果LongClickListener不为null，则会执行回调，同时如果LongClickListener.onClick返回true，才把mHasPerformedLongPress设置为true;否则mHasPerformedLongPress依然为false;也就说如果在LongClickListener我们返回true那么就不会只执行click事件，因为if就进不去了，无法执行click事件，可以看up
### MOVE
主要就是检测用户是否划出控件，如果划出了：
115ms内，直接移除mPendingCheckForTap；
115ms后，则将标志中的PRESSED去除，同时移除长按的检查：removeLongPressCallback();
### UP
a、如果115ms内，触发UP，此时标志为PREPRESSED，则执行UnsetPressedState，setPressed(false);会把setPress转发下去，可以在View中复写dispatchSetPressed方法接收；
b、如果是115ms-500ms间，即长按还未发生，则首先移除长按检测，执行onClick回调；
c、如果是500ms以后，那么有两种情况：
i.设置了onLongClickListener，且onLongClickListener.onClick返回true，则点击事件OnClick事件无法触发；
ii.没有设置onLongClickListener或者onLongClickListener.onClick返回false，则点击事件OnClick事件依然可以触发；
d、最后执行mUnsetPressedState.run()，将setPressed传递下去，然后将PRESSED标识去除；
如果你没有调用super.dispatchTouchEvent，直接return返回值，就不会执行onTouchEvent和ontouch方法了，因为你复写了view的方法dispatchTouchEvent，所以不会调用了。
