Android学习笔记——View事件分发(上)
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<pre name="code" class="java"><pre name="code" class="java"><pre name="code" class="java"> if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED && li.mOnTouchListener.onTouch(this, event)) { result = true; }
/** * view 的事件分发 * 1.返回true,说明可以响应down事件和up事件 * 2.返回false,只会响应down事件,不会响应up事件 * 在downs事件如果能处理(消费)当前事件,那么在up的时候,也会把事件传递给当前的view * 在downs事件如果不能处理(消费)当前事件,那么在up的时候,也不会把事件传递给当前的view * a.判断mOnTouchListener是否为空 * b. 判断当前控件是否可用 * c. 判断view的onTouch * d. 如果一个返回为false, 那么就会调用onTouchEvent * @author Administrator * */
</pre><pre name="code" class="java">一段源码 <span style="font-family: Arial, Helvetica, sans-serif;">onTouchEvent</span>
public boolean onTouchEvent(MotionEvent event) { final float x = event.getX(); final float y = event.getY(); final int viewFlags = mViewFlags; if ((viewFlags & ENABLED_MASK) == DISABLED) { if (event.getAction() == MotionEvent.ACTION_UP && (mPrivateFlags & PFLAG_PRESSED) != 0) { setPressed(false); } // 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; } } if (((viewFlags & CLICKABLE) == CLICKABLE || (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)) { switch (event.getAction()) { case MotionEvent.ACTION_UP: 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) { // 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(); } break; case MotionEvent.ACTION_DOWN: mHasPerformedLongPress = false; 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); } break; case MotionEvent.ACTION_CANCEL: setPressed(false); removeTapCallback(); removeLongPressCallback(); break; case MotionEvent.ACTION_MOVE: drawableHotspotChanged(x, y); // Be lenient about moving outside of buttons if (!pointInView(x, y, mTouchSlop)) { // Outside button removeTapCallback(); if ((mPrivateFlags & PFLAG_PRESSED) != 0) { // Remove any future long press/tap checks removeLongPressCallback(); setPressed(false); } } break; } return true; } return false; }
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从ImageView和Button分别解析各自的事件分发。down?up?protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main); iv_img = (ImageView) findViewById(R.id.img); button = (Button) findViewById(R.id.button); //点击ImageView 按钮,只有一次 /** * return true; 说明能销毁这个事件 * return false; down处理不了,up 事件就不会传入 */ iv_img.setOnTouchListener(new OnTouchListener() {@Overridepublic boolean onTouch(View v, MotionEvent event) {System.out.println("-iv_img--onTouch-" +event.getAction());// return false; 只能处理down事件,只打印一次,imageView不具备点击事件return true;}}); //button有很多次 button.setOnTouchListener(new OnTouchListener() {@Overridepublic boolean onTouch(View v, MotionEvent event) {System.out.println("-button--onTouch-" +event.getAction());return true;}}); //点击事件 iv_img.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {System.out.println("-iv_img--onClick-");}}); System.out.println("--iv_img-----" + iv_img.isEnabled()); /** * ListenerInfo li = mListenerInfo; if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED //p判断组件是否可用 && li.mOnTouchListener.onTouch(this, event)) { result = true; } */ //点击事件 button.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {System.out.println("-button--onClick-");}}); System.out.println("--button-----" + button.isEnabled()); }
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