而mDecor是一个继承FrameLayout的DecorView，就这样把事件分发到ViewGroup上了。
三、ViewGroup的dispatchTouchEvent 3.1 ViewGroup拦截事件的情况 // Check for interception. final boolean intercepted; if (actionMasked == MotionEvent.ACTION_DOWN || mFirstTouchTarget != null) { final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0; if (!disallowIntercept) { intercepted = onInterceptTouchEvent(ev); 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; }这里分为2种情况会判断是否需要拦截，也就是当某一条件成立时，会执行onInterceptTouchEvent判断是否需要拦截事件。
当actionMasked == MotionEvent.ACTION_DOWN时。
当mFirstTouchTarget != null时。mFirstTouchTarget是成功处理事件的ViewGroup的子View，也就是ViewGroup的子View在以下情况返回true时，这个在log分析流程图轻易得到：
2.1 dispatchTouchEvent返回true
2.2 如果子View是ViewGroup时，onInterceptTouchEvent、onTouchEvent返回true
另外还有一种情况是disallowIntercept为true时，intercepted直接赋值false不进行拦截。FLAG_DISALLOW_INTERCEPT是通过requestDisallowInterceptTouchEvent方法来设置的，用于在子View中设置，设置后ViewGroup只能拦截down事件，无法拦截其他move、up、cancel事件。为什么ViewGroup还能拦截down事件呢？因为ViewGroup在down事件时进行了重置，看看以下代码
// 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(); } private void resetTouchState() { clearTouchTargets(); resetCancelNextUpFlag(this); mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT; mNestedScrollAxes = SCROLL_AXIS_NONE; }通过源码可以了解到，ViewGroup拦截事件后，不再调用onInterceptTouchEvent，而是直接交给mFirstTouchTarget的onTouchEvent处理,如果该onTouchEvent不处理最终会交给Activity的onTouchEvent。
3.2 ViewGroup不拦截事件的情况ViewGroup不拦截事件时，会遍历子View，使事件分发到子View进行处理。
final View[] children = mChildren; for (int i = childrenCount - 1; i >= 0; i--) { final int childIndex = getAndVerifyPreorderedIndex( childrenCount, i, customOrder); final View child = getAndVerifyPreorderedView( preorderedList, children, childIndex); // If there is a view that has accessibility focus we want it // to get the event first and if not handled we will perform a // normal dispatch. We may do a double iteration but this is // safer given the timeframe. if (childWithAccessibilityFocus != null) { if (childWithAccessibilityFocus != child) { continue; } childWithAccessibilityFocus = null; i = childrenCount - 1; } if (!canViewReceivePointerEvents(child) || !isTransformedTouchPointInView(x, y, child, null)) { ev.setTargetAccessibilityFocus(false); 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(); 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; } mLastTouchDownX = ev.getX(); mLastTouchDownY = ev.getY(); newTouchTarget = addTouchTarget(child, idBitsToAssign); alreadyDispatchedToNewTouchTarget = true; break; } } 3.2.1 寻找可接收事件的子View