一、在ViewGroup 事件分發
ViewGroup#dispatchTouchEvent 分發事件
public boolean dispatchTouchEvent(MotionEvent ev) {
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
}
// 殘障人事的輔助類，智能聊天
if (ev.isTargetAccessibilityFocus() && isAccessibilityFocusedViewOrHost()) {
ev.setTargetAccessibilityFocus(false);
}
boolean handled = false;
if (onFilterTouchEventForSecurity(ev)) {
final int action = ev.getAction();
final int actionMasked = action & MotionEvent.ACTION_MASK;
// Handle an initial down.
// 多指還單指，只會執行一次 -- Action_point_donw
// 重置狀態
if (actionMasked == MotionEvent.ACTION_DOWN) {
cancelAndClearTouchTargets(ev);
resetTouchState();
}
/***********************************第一塊, 檢測是否攔截*******************************/
// Check for interception.
// 檢測是否攔截 -- 父容器的權利
final boolean intercepted;
if (actionMasked == MotionEvent.ACTION_DOWN
|| mFirstTouchTarget != null) {
final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
// disallowIntercept 決定 onInterceptTouchEvent 會不會執行
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;
}
// If intercepted, start normal event dispatch. Also if there is already
// a view that is handling the gesture, do normal event dispatch.
if (intercepted || mFirstTouchTarget != null) {
ev.setTargetAccessibilityFocus(false);
}
// Check for cancelation.
final boolean canceled = resetCancelNextUpFlag(this)
|| actionMasked == MotionEvent.ACTION_CANCEL;
// Update list of touch targets for pointer down, if needed.
final boolean isMouseEvent = ev.getSource() == InputDevice.SOURCE_MOUSE;
// 默認情況爲true -- 是否可以多指
final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0
&& !isMouseEvent;
TouchTarget newTouchTarget = null;
boolean alreadyDispatchedToNewTouchTarget = false;
/************************第二塊, 遍歷子View，詢問子View是否處理事件*******************/
// 在 if 中分發事件
if (!canceled && !intercepted) {
View childWithAccessibilityFocus = ev.isTargetAccessibilityFocus()
? findChildWithAccessibilityFocus() : null;
// 第一根手指按下時，命中if
if (actionMasked == MotionEvent.ACTION_DOWN
// 第二根或n根手指按下，命中if
|| (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)
// 鼠標
|| actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
// 如果事件是 MotionEvent.ACTION_DOWN，actionIndex = 0
final int actionIndex = ev.getActionIndex(); // always 0 for down
// 手指的id ，最多識別多少手指？32位，位運算，一位表示一個手指，0000000000111
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);
// 有多少個子孩子
final int childrenCount = mChildrenCount;
if (newTouchTarget == null && childrenCount != 0) {
final float x =
isMouseEvent ? ev.getXCursorPosition() : ev.getX(actionIndex);
final float y =
isMouseEvent ? ev.getYCursorPosition() : ev.getY(actionIndex);
// Find a child that can receive the event.
// Scan children from front to back.
// 將子View 進行排序
final ArrayList<View> preorderedList = buildTouchDispatchChildList();
final boolean customOrder = preorderedList == null
&& isChildrenDrawingOrderEnabled();
final View[] children = mChildren;
// 倒序遍歷
for (int i = childrenCount - 1; i >= 0; i--) {
final int childIndex = getAndVerifyPreorderedIndex(
childrenCount, i, customOrder);
final View child = getAndVerifyPreorderedView(
preorderedList, children, childIndex);
// 是否能處理點擊事件
// view是否可見或者animotion不爲空
if (!child.canReceivePointerEvents()
|| !isTransformedTouchPointInView(x, y, child, null)) {
continue;
}
// 單指操作，爲null，多指纔不爲空
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);
// 詢問 child 是否處理事件，如果child處理，則命中if -- 遞歸
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();
// 創建了 newTouchTarget == mFirstTouchTarget
newTouchTarget = addTouchTarget(child, idBitsToAssign);
// 後面會用到
alreadyDispatchedToNewTouchTarget = true;
// 退出循環，不再循環其他child
break;
}
// The accessibility focus didn't handle the event, so clear
// the flag and do a normal dispatch to all children.
ev.setTargetAccessibilityFocus(false);
}
if (preorderedList != null) preorderedList.clear();
}
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;
}
}
}
/************************第三塊, 判斷子View處理還是自己處理事件*******************/
// Dispatch to touch targets.
// 沒有child處理事件的時候
if (mFirstTouchTarget == null) {
// No touch targets so treat this as an ordinary view.
// 詢問自己是否處理
handled = dispatchTransformedTouchEvent(ev, canceled, null,
TouchTarget.ALL_POINTER_IDS);
} else {
// 有子View處理了事件
// 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循環爲單指操作時 只會執行一次
while (target != null) {
// 單指操作 next = null
final TouchTarget next = target.next;
// if命中，直接返回 handle，不作處理
if (alreadyDispatchedToNewTouchTarget && target == newTouchTarget) {
handled = true;
} else {
final boolean cancelChild = resetCancelNextUpFlag(target.child)
|| intercepted;
// 詢問 target.child（前面保存的）
if (dispatchTransformedTouchEvent(ev, cancelChild,
target.child, target.pointerIdBits)) {
handled = true;
}
// 爲true 取消child處理事件
if (cancelChild) {
if (predecessor == null) {
// mFirstTouchTarget 置爲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;
}
可見ViewGroup#dispatchTouchEvent分爲三部分
- 1、是否攔截子View,intercepted爲true攔截，爲false 不攔截
- 2、遍歷子View，詢問子View是否處理事件
- 3、如果子View都不處理，詢問自己是否處理事件
1.1、 取消事件和重置狀態
- 執行取消事件
private void cancelAndClearTouchTargets(MotionEvent event) {
if (mFirstTouchTarget != null) {
boolean syntheticEvent = false;
if (event == null) {
final long now = SystemClock.uptimeMillis();
event = MotionEvent.obtain(now, now,
MotionEvent.ACTION_CANCEL, 0.0f, 0.0f, 0);
event.setSource(InputDevice.SOURCE_TOUCHSCREEN);
syntheticEvent = true;
}
for (TouchTarget target = mFirstTouchTarget; target != null; target = target.next) {
resetCancelNextUpFlag(target.child);
// 執行取消事件
dispatchTransformedTouchEvent(event, true, target.child, target.pointerIdBits);
}
// 清除 TouchTarget
clearTouchTargets();
if (syntheticEvent) {
event.recycle();
}
}
}
- 重置狀態
private void resetTouchState() {
clearTouchTargets();
resetCancelNextUpFlag(this);
// 重置了 mGroupFlags 的值
mGroupFlags &= ~FLAG_DISALLOW_INTERCEPT;
mNestedScrollAxes = SCROLL_AXIS_NONE;
}
1.2、攔截事件
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (ev.isFromSource(InputDevice.SOURCE_MOUSE)
&& ev.getAction() == MotionEvent.ACTION_DOWN
&& ev.isButtonPressed(MotionEvent.BUTTON_PRIMARY)
&& isOnScrollbarThumb(ev.getX(), ev.getY())) {
return true;
}
return false;
}
我們在自定義View 裏面可以重寫這個方法來處理攔截事件
1.3、詢問子View是否處理事件
在裏面會對子View 根據懸浮層進行排序
public ArrayList<View> buildTouchDispatchChildList() {
return buildOrderedChildList();
}
ArrayList<View> buildOrderedChildList() {
final int childrenCount = mChildrenCount;
if (childrenCount <= 1 || !hasChildWithZ()) return null;
if (mPreSortedChildren == null) {
mPreSortedChildren = new ArrayList<>(childrenCount);
} else {
// callers should clear, so clear shouldn't be necessary, but for safety...
mPreSortedChildren.clear();
mPreSortedChildren.ensureCapacity(childrenCount);
}
final boolean customOrder = isChildrenDrawingOrderEnabled();
for (int i = 0; i < childrenCount; i++) {
// add next child (in child order) to end of list
final int childIndex = getAndVerifyPreorderedIndex(childrenCount, i, customOrder);
final View nextChild = mChildren[childIndex];
// 默認不設置，則爲0
final float currentZ = nextChild.getZ();
// insert ahead of any Views with greater Z
int insertIndex = i;
while (insertIndex > 0 && mPreSortedChildren.get(insertIndex - 1).getZ() > currentZ) {
insertIndex--;
}
// xml中佈局 靠後的，放在集合後面
mPreSortedChildren.add(insertIndex, nextChild);
}
return mPreSortedChildren;
}
private int getAndVerifyPreorderedIndex(int childrenCount, int i, boolean customOrder) {
final int childIndex;
if (customOrder) {
final int childIndex1 = getChildDrawingOrder(childrenCount, i);
if (childIndex1 >= childrenCount) {
throw new IndexOutOfBoundsException("getChildDrawingOrder() "
+ "returned invalid index " + childIndex1
+ " (child count is " + childrenCount + ")");
}
childIndex = childIndex1;
} else {
childIndex = i;
}
return childIndex;
}
1.4、詢問子View處理，還是自己處理
private boolean dispatchTransformedTouchEvent(MotionEvent event, boolean cancel,
View child, int desiredPointerIdBits) {
final boolean handled;
// Canceling motions is a special case. We don't need to perform any transformations
// or filtering. The important part is the action, not the contents.
final int oldAction = event.getAction();
//當取消事件會執行這裏，內部攔截也會走
if (cancel || oldAction == MotionEvent.ACTION_CANCEL) {
//把事件先設爲 ACTION_CANCEL
event.setAction(MotionEvent.ACTION_CANCEL);
if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
handled = child.dispatchTouchEvent(event);
}
//設至回原來的事件
event.setAction(oldAction);
return handled;
}
// Calculate the number of pointers to deliver.
final int oldPointerIdBits = event.getPointerIdBits();
final int newPointerIdBits = oldPointerIdBits & desiredPointerIdBits;
// If for some reason we ended up in an inconsistent state where it looks like we
// might produce a motion event with no pointers in it, then drop the event.
if (newPointerIdBits == 0) {
return false;
}
final MotionEvent transformedEvent;
if (newPointerIdBits == oldPointerIdBits) {
if (child == null || child.hasIdentityMatrix()) {
if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
event.offsetLocation(offsetX, offsetY);
handled = child.dispatchTouchEvent(event);
event.offsetLocation(-offsetX, -offsetY);
}
return handled;
}
transformedEvent = MotionEvent.obtain(event);
} else {
transformedEvent = event.split(newPointerIdBits);
}
// Perform any necessary transformations and dispatch.
if (child == null) {
// View.dispatchTouchEvent(處理事件)
handled = super.dispatchTouchEvent(transformedEvent);
} else {
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
transformedEvent.offsetLocation(offsetX, offsetY);
if (! child.hasIdentityMatrix()) {
transformedEvent.transform(child.getInverseMatrix());
}
// child是容器，ViewGroup.dispatchTouchEvent;child是View，View.dispatchTouchEvent(處理事件)
handled = child.dispatchTouchEvent(transformedEvent);
}
// Done.
transformedEvent.recycle();
return handled;
}
二、在View中 事件處理
public boolean dispatchTouchEvent(MotionEvent event) {
// 最前面這一段就是判斷當前事件是否能獲得焦點，如果不能獲得焦點或者不存在一個View，
// 那我們就直接返回False跳出循環
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);
}
//設置返回的默認值，判斷時間是否消費
boolean result = false;
//這段是系統調試方面，可以直接忽略
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}
//Android用一個32位的整型值表示一次TouchEvent事件,低8位表示touch事件的具體動作，
// 比如按下，擡起，滑動，還有多點觸控時的按下，擡起，這個和單點是區分開的，下面看具體的方法:
//1 getAction:觸摸動作的原始32位信息，包括事件的動作，觸控點信息
//2 getActionMasked:觸摸的動作,按下，擡起，滑動，多點按下，多點擡起
//3 getActionIndex:觸控點信息
final int actionMasked = event.getActionMasked();
if (actionMasked == MotionEvent.ACTION_DOWN) {
// 當我們手指按到View上時,其他的依賴滑動都要先停下
stopNestedScroll();
}
//過濾掉一些不合法的事件,比如當前的View的窗口被遮擋了。
if (onFilterTouchEventForSecurity(event)) {
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
result = true;
}
//ListenerInfo 是view的一個內部類 裏面有各種各樣的listener
ListenerInfo li = mListenerInfo;
//判斷是否執行 OnTouch 事件
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
//事件消費
result = true;
}
//onTouch 返回 false 執行，即事件沒有消費
if (!result && onTouchEvent(event)) {
//事件消費
result = true;
}
}
if (!result && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
// 如果這是手勢的結尾，則在嵌套滾動後清理
if (actionMasked == MotionEvent.ACTION_UP ||
actionMasked == MotionEvent.ACTION_CANCEL ||
(actionMasked == MotionEvent.ACTION_DOWN && !result)) {
stopNestedScroll();
}
return result;
}
接下來看View#onTouchEvent判斷是否消費
public boolean onTouchEvent(MotionEvent event) {
// 獲取動作點擊屏幕的位置座標
final float x = event.getX();
final float y = event.getY();
final int viewFlags = mViewFlags;
final int action = event.getAction();
//如果當前View是一個DISABLED狀態，且當前View是一個可點擊或者是可長按的狀態
// 則clickable返回true。表示當前事件在此消耗且不做處理
final boolean clickable = ((viewFlags & CLICKABLE) == CLICKABLE
|| (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)
|| (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE;
//如果當前View狀態爲DISABLED
if ((viewFlags & ENABLED_MASK) == DISABLED) {
//如果View的狀態是被按壓過，且當擡起事件產生，重置View狀態爲未按壓，刷新Drawable的狀態
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;
}
// 如果設置了觸摸代理
if (mTouchDelegate != null) {
//就交給mTouchDelegate.onTouchEvent處理，如果返回true，則事件被處理了，則不會向下傳遞
if (mTouchDelegate.onTouchEvent(event)) {
return true;
}
}
//如果當前View的狀態是可點擊或者是可長按的，就對事件流進行細節處理
if (clickable || (viewFlags & TOOLTIP) == TOOLTIP) {
switch (action) {
case MotionEvent.ACTION_UP:
//如果是擡起的手勢
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
if ((viewFlags & TOOLTIP) == TOOLTIP) {
handleTooltipUp();
}
//清除各種狀態
if (!clickable) {
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
break;
}
//prepressed指的是，如果view包裹在一個scrolling View中，可能會進行滑動處理，
// 所以設置了一個prePress的狀態
//大致是等待一定時間，然後沒有被父類攔截了事件，則認爲是點擊到了當前的view,從而顯示點擊態
boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
//如果是pressed狀態或者是prepressed狀態，才進行處理
if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
// 如果設定了獲取焦點，那麼調用requestFocus獲得焦點
boolean focusTaken = false;
if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
focusTaken = requestFocus();
}
////在釋放之前給用戶顯示View的prepressed的狀態，狀態需要改變爲PRESSED，
// 並且需要將背景變爲按下的狀態爲了讓用戶感知到
if (prepressed) {
setPressed(true, x, y);
}
//是否處理過長按操作了，如果是，則直接返回
if (!mHasPerformedLongPress && !mIgnoreNextUpEvent) {
// 如果不是長按的話，僅僅是一個Tap，所以移除長按的回調
removeLongPressCallback();
// Only perform take click actions if we were in the pressed state
if (!focusTaken) {
//UI子線程去執行click，爲了讓click事件開始的時候其他視覺發生變化不影響。
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
//如果post消息失敗，直接調用處理click事件
if (!post(mPerformClick)) {
performClickInternal();
}
}
}
if (mUnsetPressedState == null) {
mUnsetPressedState = new UnsetPressedState();
}
if (prepressed) {
//ViewConfiguration.getPressedStateDuration() 獲得的是按下效果顯示的時間
//由PRESSED_STATE_DURATION常量指定,目的是讓用戶感知到click的效果
postDelayed(mUnsetPressedState,
ViewConfiguration.getPressedStateDuration());
} else if (!post(mUnsetPressedState)) {
// 如果通過post(Runnable runnable)方式調用失敗，則直接調用
mUnsetPressedState.run();
}
//移除Tap的回調 重置View的狀態
removeTapCallback();
}
mIgnoreNextUpEvent = false;
break;
case MotionEvent.ACTION_DOWN:
//如果是按下的手勢
if (event.getSource() == InputDevice.SOURCE_TOUCHSCREEN) {
mPrivateFlags3 |= PFLAG3_FINGER_DOWN;
}
//在觸摸事件中執行按鈕相關的動作,如果返回true則表示已經消耗了down
mHasPerformedLongPress = false;
if (!clickable) {
//僅在View支持長按時執行有效，否則直接退出方法
checkForLongClick(
ViewConfiguration.getLongPressTimeout(),
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__LONG_PRESS);
break;
}
//處理如鼠標的右鍵的
if (performButtonActionOnTouchDown(event)) {
break;
}
//判斷當前view是否是在滾動器當中
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;
//將view的狀態變爲PREPRESSED，檢測是Tap還是長按事件
if (mPendingCheckForTap == null) {
mPendingCheckForTap = new CheckForTap();
}
//如果是在滾動器當中，在滾動器當中的話延遲返回事件，
// 延遲時間爲 ViewConfiguration.getTapTimeout()=100毫秒
//在給定的tapTimeout時間之內,用戶的觸摸沒有移動,就當作用戶是想點擊,而不是滑動.
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(
ViewConfiguration.getLongPressTimeout(),
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__LONG_PRESS);
}
break;
case MotionEvent.ACTION_CANCEL:
//接收到系統發出的ACTION_CANCLE事件時，重置狀態， 將所有的狀態設置爲最初始
if (clickable) {
setPressed(false);
}
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
break;
case MotionEvent.ACTION_MOVE:
if (clickable) {
//將實時位置傳遞給背景（前景）圖片
drawableHotspotChanged(x, y);
}
final int motionClassification = event.getClassification();
final boolean ambiguousGesture =
motionClassification == MotionEvent.CLASSIFICATION_AMBIGUOUS_GESTURE;
int touchSlop = mTouchSlop;
if (ambiguousGesture && hasPendingLongPressCallback()) {
if (!pointInView(x, y, touchSlop)) {
// The default action here is to cancel long press. But instead, we
// just extend the timeout here, in case the classification
// stays ambiguous.
removeLongPressCallback();
long delay = (long) (ViewConfiguration.getLongPressTimeout()
* mAmbiguousGestureMultiplier);
// Subtract the time already spent
delay -= event.getEventTime() - event.getDownTime();
checkForLongClick(
delay,
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__LONG_PRESS);
}
touchSlop *= mAmbiguousGestureMultiplier;
}
// 判斷當前滑動事件是否還在當前view當中，不是就執行下面的方法
if (!pointInView(x, y, touchSlop)) {
// 移除PREPRESSED狀態和對應回調s
removeTapCallback();
removeLongPressCallback();
if ((mPrivateFlags & PFLAG_PRESSED) != 0) {
//是PRESSED就移除長按檢測，並移除PRESSED狀態
setPressed(false);
}
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
}
final boolean deepPress =
motionClassification == MotionEvent.CLASSIFICATION_DEEP_PRESS;
if (deepPress && hasPendingLongPressCallback()) {
// process the long click action immediately
removeLongPressCallback();
checkForLongClick(
0 /* send immediately */,
x,
y,
TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__DEEP_PRESS);
}
break;
}
return true;
}
return false;
}
三、onTouch 和 onClick 執行的位置和關係
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
btn.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
//當返回 true, onClick不會執行
//當返回 false, onClick會執行
return false;
}
});
事件關係
當 onTouch 返回 true, onClick不會執行
當 onTouch 返回 false, onClick會執行
1.1、源碼流程
我們從View的dispatchTouchEvent處事件處理開始分析
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) {
// 如果是Down停止滾動
stopNestedScroll();
}
if (onFilterTouchEventForSecurity(event)) {
if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
result = true;
}
//ListenerInfo 裏面存儲初始化的事件
ListenerInfo li = mListenerInfo;
//ListenerInfo ， mOnTouchListener 非空執行 onTouch 事件
if (li != null && li.mOnTouchListener != null
&& (mViewFlags & ENABLED_MASK) == ENABLED
//執行 onTouch 事件
&& li.mOnTouchListener.onTouch(this, event)) {
result = true;
}
//短路與，當result 爲true ，onTouchEvent不執行
//在 onTouchEvent 裏面會處理 onClick 事件
if (!result && onTouchEvent(event)) {
result = true;
}
}
if (!result && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
// of the gesture.
if (actionMasked == MotionEvent.ACTION_UP ||
actionMasked == MotionEvent.ACTION_CANCEL ||
(actionMasked == MotionEvent.ACTION_DOWN && !result)) {
stopNestedScroll();
}
return result;
}
執行點擊事件，調用View的內部類PerformClick
private final class PerformClick implements Runnable {
@Override
public void run() {
recordGestureClassification(TOUCH_GESTURE_CLASSIFIED__CLASSIFICATION__SINGLE_TAP);
performClickInternal();
}
}
private boolean performClickInternal() {
// be interested on.
notifyAutofillManagerOnClick();
return performClick();
}
在View#onTouchEvent裏面的ACTION_UP事件中處理點擊事件的
case MotionEvent.ACTION_UP:
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
if ((viewFlags & TOOLTIP) == TOOLTIP) {
handleTooltipUp();
}
if (!clickable) {
//清除各種狀態
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
break;
}
//prepressed指的是，如果view包裹在一個scrolling View中，
//可能會進行滑動處理，所以設置了一個prePress的狀態
//大致是等待一定時間，然後沒有被父類攔截了事件，
//則認爲是點擊到了當前的view,從而顯示點擊態
boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
// 如果設定了獲取焦點，那麼調用requestFocus獲得焦點
boolean focusTaken = false;
if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
focusTaken = requestFocus();
}
//在釋放之前給用戶顯示View的prepressed的狀態，狀態需要改變爲PRESSED，
//並且需要將背景變爲按下的狀態爲了讓用戶感知到
if (prepressed) {
setPressed(true, x, y);
}
if (!mHasPerformedLongPress && !mIgnoreNextUpEvent) {
//如果不是長按的話，僅僅是一個Tap，所以移除長按的回調
removeLongPressCallback();
// Only perform take click actions if we were in the pressed state
if (!focusTaken) {
// UI子線程去執行click，爲了讓click事件開始的時候其他視覺發生變化不影響
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
//如果post消息失敗，直接調用處理click事件
if (!post(mPerformClick)) {
performClickInternal();
}
}
}
if (mUnsetPressedState == null) {
mUnsetPressedState = new UnsetPressedState();
}
if (prepressed) {
//ViewConfiguration.getPressedStateDuration() 獲得的是按下效果顯示的時間,
//由PRESSED_STATE_DURATION = 64 常量指定，單位爲毫秒
//目的是讓用戶感知到click的效果
postDelayed(mUnsetPressedState,
ViewConfiguration.getPressedStateDuration());
} else if (!post(mUnsetPressedState)) {
//如果通過post(Runnable runnable)方式調用失敗，則直接調用
mUnsetPressedState.run();
}
//移除Tap的回調 重置View的狀態
removeTapCallback();
}
mIgnoreNextUpEvent = false;
break;
在 post 方法中發送消息
public boolean post(Runnable action) {
final AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null) {
return attachInfo.mHandler.post(action);
}
getRunQueue().post(action);
return true;
}
點擊事件最終在View#performClick()方法中執行
public boolean performClick() {
notifyAutofillManagerOnClick();
final boolean result;
final ListenerInfo li = mListenerInfo;
if (li != null && li.mOnClickListener != null) {
playSoundEffect(SoundEffectConstants.CLICK);
//執行onClick事件
li.mOnClickListener.onClick(this);
result = true;
} else {
result = false;
}
sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
notifyEnterOrExitForAutoFillIfNeeded(true);
return result;
}