View的事件处理主要有两个方法
- dispatchTouchEvent
- onTouchEvent
另外还可以设置
- setOnTouchListener(new View.OnTouchListener() {
- setOnClickListener(new View.OnClickListener() {
- setOnLongClickListener(new View.OnLongClickListener() {
新建实例：
public class TestButton extends Button{
private static final String TAG = "-EVENT";
public TestButton(Context context) {
super(context);
}
public TestButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
public TestButton(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
Log.d(TAG, "dispatchTouchEvent: View "+event.getAction());
return super.dispatchTouchEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
Log.d(TAG, "onTouchEvent: View "+event.getAction());
return super.onTouchEvent(event);
}
}
然后在activity中设置
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ll_parent = findViewById(R.id.ll_parent);
btn_test = findViewById(R.id.btn_test);
btn_test.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
Log.d(TAG, "onTouch: View "+event.getAction());
return false;
}
});
btn_test.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(TAG, "onClick: View");
}
});
btn_test.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
Log.d(TAG, "onLongClick: View");
return false;
}
});
}
在点击Button时，Log内容
ACTION_DOWN = 0, ACTION_UP = 1, ACTION_MOVE = 2
03-19 16:23:59.810 15020-15020/com.jiang.eventtest D/-EVENT: dispatchTouchEvent: View 0
03-19 16:23:59.810 15020-15020/com.jiang.eventtest D/-EVENT: onTouch: View 0
03-19 16:23:59.810 15020-15020/com.jiang.eventtest D/-EVENT: onTouchEvent: View 0
03-19 16:23:59.910 15020-15020/com.jiang.eventtest D/-EVENT: dispatchTouchEvent: View 2
03-19 16:23:59.910 15020-15020/com.jiang.eventtest D/-EVENT: onTouch: View 2
03-19 16:23:59.910 15020-15020/com.jiang.eventtest D/-EVENT: onTouchEvent: View 2
...
03-19 16:24:00.310 15020-15020/com.jiang.eventtest D/-EVENT: onLongClick: View
...
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: dispatchTouchEvent: View 2
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: onTouch: View 2
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: onTouchEvent: View 2
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: dispatchTouchEvent: View 1
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: onTouch: View 1
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: onTouchEvent: View 1
03-19 16:24:01.970 15020-15020/com.jiang.eventtest D/-EVENT: onClick: View
从上面可以看到调用的顺序分别是：
dispatchTouchEvent --> onTouch --> onTouchEvent -->onLongClick-->onClick
首先看下View的dispatchTouchEvent：
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);
}
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
stopNestedScroll();
}
if (onFilterTouchEventForSecurity(event)) {
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
result = true;
}
//noinspection SimplifiableIfStatement
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
result = true;
}
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;
}
重点在：
if (onFilterTouchEventForSecurity(event)) {//判断View是否被遮盖，时返回false
//View为enable && 事件作为滚动条拖动处理
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
result = true;
}
//noinspection SimplifiableIfStatement
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
result = true;
}
if (!result && onTouchEvent(event)) {
result = true;
}
}
ListenerInfo li中包含了各种监听包括OnTouchListener，
在调用setOnTouchListener时：
public void setOnTouchListener(OnTouchListener l) {
getListenerInfo().mOnTouchListener = l;
}
ListenerInfo getListenerInfo() {
if (mListenerInfo != null) {
return mListenerInfo;
}
mListenerInfo = new ListenerInfo();
return mListenerInfo;
}
这里可以看到在先调用的是我们设置OnTouchListener.onTouch,如果没有设置或者在onTouch中返回的false，才会调用onTouchEvent
public boolean onTouchEvent(MotionEvent event) {
final float x = event.getX();
final float y = event.getY();
final int viewFlags = mViewFlags;
final int action = event.getAction();
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.
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
if (!post(mPerformClick)) {
performClick();
}
}
}
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(0, x, y);
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(0, x, y);
}
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);
}
// Be lenient about moving outside of buttons
if (!pointInView(x, y, mTouchSlop)) {
// Outside button
// Remove any future long press/tap checks
removeTapCallback();
removeLongPressCallback();
if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
setPressed(false);
}
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
}
break;
}
return true;
}
return false;
}
其中
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;
}
判断该View是否可以点击，不可的话则设置点击的状态并返回
if (mTouchDelegate != null) {
if (mTouchDelegate.onTouchEvent(event)) {
return true;
}
}
如果设置了mTouchDelegate，则会将事件交给代理者处理，直接return true
1. MotionEvent.ACTION_DOWN:
mHasPerformedLongPress = false;
boolean isInScrollingContainer = isInScrollingContainer();
当View在滚动容器内时,为false
private final class CheckForTap implements Runnable {
public float x;
public float y;
@Override
public void run() {
mPrivateFlags &= ~PFLAG_PREPRESSED;
setPressed(true, x, y);
checkForLongClick(ViewConfiguration.getTapTimeout(), x, y);
}
}
这里ViewConfiguration.getTapTimeout()为100
private void setPressed(boolean pressed, float x, float y) {
if (pressed) {
drawableHotspotChanged(x, y);
}
setPressed(pressed);
}
public void setPressed(boolean pressed) {
final boolean needsRefresh = pressed != ((mPrivateFlags & PFLAG_PRESSED) == PFLAG_PRESSED);
if (pressed) {
mPrivateFlags |= PFLAG_PRESSED;
} else {
mPrivateFlags &= ~PFLAG_PRESSED;
}
if (needsRefresh) {
refreshDrawableState();
}
dispatchSetPressed(pressed);
}
private void checkForLongClick(int delayOffset, float x, float y) {
if ((mViewFlags & LONG_CLICKABLE) == LONG_CLICKABLE || (mViewFlags & TOOLTIP) == TOOLTIP) {
mHasPerformedLongPress = false;
if (mPendingCheckForLongPress == null) {
mPendingCheckForLongPress = new CheckForLongPress();
}
mPendingCheckForLongPress.setAnchor(x, y);
mPendingCheckForLongPress.rememberWindowAttachCount();
mPendingCheckForLongPress.rememberPressedState();
postDelayed(mPendingCheckForLongPress,
//值为500
ViewConfiguration.getLongPressTimeout() - delayOffset);
}
}
private final class CheckForLongPress implements Runnable {
private int mOriginalWindowAttachCount;
private float mX;
private float mY;
private boolean mOriginalPressedState;
@Override
public void run() {
if ((mOriginalPressedState == isPressed()) && (mParent != null)
&& mOriginalWindowAttachCount == mWindowAttachCount) {
if (performLongClick(mX, mY)) {
mHasPerformedLongPress = true;
}
}
}
- 在MotionEvent.ACTION_DOWN时首先将mHasPerformedLongPress=falsee
- 延时100毫秒执行 或 立即 执行setPressed和checkForLongClick，改变mPrivateFlags的状态，并且在500ms内View的状态仍然是PFLAG_PRESSED，则执行performLongClick，在其中回调onLongClck,并且mHasPerformedLongPress = true
2. MotionEvent.ACTION_MOVE
if (!pointInView(x, y, mTouchSlop)) {
// Outside button
// Remove any future long press/tap checks
removeTapCallback();
removeLongPressCallback();
if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
setPressed(false);
}
- 如果手指移出View外，移除回调和长按回调
- 如果mPrivateFlags满住条件，还原View状态
3. MotionEvent.ACTION_UP
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.
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
if (!post(mPerformClick)) {
performClick();
}
}
}
public boolean performClick() {
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;
}
private final class UnsetPressedState implements Runnable {
@Override
public void run() {
setPressed(false);
}
}
- 移除长按回调
- 回调onClick;
- 重置View的状态。
other
若在onLongClick中返回false，onClick仍会回调，返回true则不会回调
总结：
- View的在dispatchTouchEvent中执行onTouch或者onTouchEvent；
- 当如设置了onTouchListener且onTouch返回false时，将会执行自身的onTouchEvent，否则不执行；
- onTouchEvent中
- ACTION_DOWN,在其中改变View的状态、背景等，检查长按任务，如果在500ms内，未抬起则回调onLongClick
- ACTION_MOVE，如果移出View内，则移出相关回调，并重置状态
- ACTION_UP，
- 如果未长按，移除长按检测；
- 回调onClick;
- 重置View状态。