源碼解析
public boolean onTouchEvent(MotionEvent event) {
final float x = event.getX();
final float y = event.getY();
final int viewFlags = mViewFlags;
//View觸摸不考慮多點觸控
final int action = event.getAction();
//可點擊 || 長按 || （長按菜單&&鼠標右鍵）
final boolean clickable = ((viewFlags & CLICKABLE) == CLICKABLE
|| (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)
|| (viewFlags & CONTEXT_CLICKABLE) == CONTEXT_CLICKABLE;
//View不可用锰瘸，返回clickable
if ((viewFlags & ENABLED_MASK) == DISABLED) {
if (action == MotionEvent.ACTION_UP && (mPrivateFlags & PFLAG_PRESSED) != 0) {
setPressed(false);
}
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
// 按鈕本可點擊但是被設(shè)置為禁用状囱，仍然消耗掉事件, 只是不做出響應(yīng)绘盟。
return clickable;
}
//點擊代理
if (mTouchDelegate != null) {
if (mTouchDelegate.onTouchEvent(event)) {
return true;
}
}
//可點擊 || tooltip（長按提示磅叛，api28引入）
if (clickable || (viewFlags & TOOLTIP) == TOOLTIP) {
switch (action) {
case MotionEvent.ACTION_UP:
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
if ((viewFlags & TOOLTIP) == TOOLTIP) {
//松手后隱藏tooltip
handleTooltipUp();
}
if (!clickable) {
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
break;
}
boolean prepressed = (mPrivateFlags & PFLAG_PREPRESSED) != 0;
//按下狀態(tài) || 預(yù)按下狀態(tài)
if ((mPrivateFlags & PFLAG_PRESSED) != 0 || prepressed) {
// take focus if we don't have it already and we should in
// touch mode.
boolean focusTaken = false;
//isFocusableInTouchMode()秽荤，實體按鍵纷责，獲取焦點
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.
//預(yù)按下狀態(tài)設(shè)置為按下
setPressed(true, x, y);
}
//處理點擊
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)) {
performClickInternal();
}
}
}
if (mUnsetPressedState == null) {
mUnsetPressedState = new UnsetPressedState();
}
if (prepressed) {
//預(yù)按下哼丈，延時取消按下狀態(tài)，
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:
//DOWN事件是否是觸摸產(chǎn)生训枢，實體按鍵也可產(chǎn)生DOWN事件托修，
PFLAG3_FINGER_DOWN影響tooltip呼出位置
if (event.getSource() == InputDevice.SOURCE_TOUCHSCREEN) {
mPrivateFlags3 |= PFLAG3_FINGER_DOWN;
}
mHasPerformedLongPress = false;
//不可點擊，設(shè)置長按監(jiān)聽（用于呼出tooltip）恒界，
if (!clickable) {
checkForLongClick(0, x, y);
break;
}
//檢測鼠標右鍵點擊
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.
//在滑動控件中
if (isInScrollingContainer) {
//設(shè)置為預(yù)按下狀態(tài)
mPrivateFlags |= PFLAG_PREPRESSED;
if (mPendingCheckForTap == null)
mPendingCheckForTap = new CheckForTap();
}
mPendingCheckForTap.x = event.getX();
mPendingCheckForTap.y = event.getY();
//延時設(shè)置按下狀態(tài)
postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
}
//不在滑動控件中
else {
// Not inside a scrolling container, so show the feedback right away
//設(shè)置為按下狀態(tài)
setPressed(true, x, y);
//設(shè)置長按檢測監(jiān)聽
checkForLongClick(0, x, y);
}
break;
case MotionEvent.ACTION_CANCEL:
//重置
if (clickable) {
setPressed(false);
}
removeTapCallback();
removeLongPressCallback();
mInContextButtonPress = false;
mHasPerformedLongPress = false;
mIgnoreNextUpEvent = false;
mPrivateFlags3 &= ~PFLAG3_FINGER_DOWN;
break;
case MotionEvent.ACTION_MOVE:
if (clickable) {
//5.0移動水波紋中心位置
drawableHotspotChanged(x, y);
}
// Be lenient about moving outside of buttons
//是否在View范圍內(nèi)
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;
}
1睦刃、返回值表示是否消耗當(dāng)前事件組，標記事件的歸屬十酣。
2涩拙、是否消費事件取決于 ACTION_DOWN 返回值 ，僅ACTION_DOWN返回值有效耸采。
3兴泥、true,消耗ACTION_DOWN事件及后續(xù)事件，后續(xù)事件全部交由當(dāng)前View處理虾宇。
4搓彻、false,放棄ACTION_DOWN事件及后續(xù)事件，后續(xù)事件不會再觸發(fā)當(dāng)前View的onTouchEvent方法嘱朽。
5旭贬、ACTION_DOWN返回ture，ACTION_MOVE返回false搪泳，Activity onTouchEvent也會觸發(fā)MOVE事件稀轨。
6狼讨、圖1為手機橫截面，黃色和藍色同為灰色子控件凝赛，且黃色和藍色有部分重疊失都，重疊區(qū)域黃色在上方于未。箭頭為DOWN事件最遠路徑冠绢。
圖1.png
