如何解決listView或scrollView+viewpager手勢沖突的問題 · 學習Android從0開始

?因為我在項目中遇到了這樣一個問題：我的主頁面是一個scrollview，里面包含了一個橫向顯示圖片的listview，在滑動橫向listview的時候scrollview也在微微上下滑動，此時的橫向listview滑動起來也是出現非常卡頓的情況。因此我百度看了很多資料，很多都講了一大篇的理論，看得頭暈眼花。我后來總結了一下，實際怎么解決這樣的問題；首先，每個listview或則scrollview的源代碼中有這么一段代碼，如下： ~~~ @Override public boolean onInterceptTouchEvent(MotionEvent ev) { /* * This method JUST determines whether we want to intercept the motion. * If we return true, onMotionEvent will be called and we do the actual * scrolling there. */ /* * Shortcut the most recurring case: the user is in the dragging * state and he is moving his finger. We want to intercept this * motion. */ final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { return true; } /* * Don't try to intercept touch if we can't scroll anyway. */ if (getScrollY() == 0 && !canScrollVertically(1)) { return false; } switch (action & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_MOVE: { /* * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check * whether the user has moved far enough from his original down touch. */ /* * Locally do absolute value. mLastMotionY is set to the y value * of the down event. */ final int activePointerId = mActivePointerId; if (activePointerId == INVALID_POINTER) { // If we don't have a valid id, the touch down wasn't on content. break; } final int pointerIndex = ev.findPointerIndex(activePointerId); if (pointerIndex == -1) { Log.e(TAG, "Invalid pointerId=" + activePointerId + " in onInterceptTouchEvent"); break; } final int y = (int) ev.getY(pointerIndex); final int yDiff = Math.abs(y - mLastMotionY); if (yDiff > mTouchSlop) { mIsBeingDragged = true; mLastMotionY = y; initVelocityTrackerIfNotExists(); mVelocityTracker.addMovement(ev); if (mScrollStrictSpan == null) { mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); } final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } } break; } case MotionEvent.ACTION_DOWN: { final int y = (int) ev.getY(); if (!inChild((int) ev.getX(), (int) y)) { mIsBeingDragged = false; recycleVelocityTracker(); break; } /* * Remember location of down touch. * ACTION_DOWN always refers to pointer index 0. */ mLastMotionY = y; mActivePointerId = ev.getPointerId(0); initOrResetVelocityTracker(); mVelocityTracker.addMovement(ev); /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when * being flinged. */ mIsBeingDragged = !mScroller.isFinished(); if (mIsBeingDragged && mScrollStrictSpan == null) { mScrollStrictSpan = StrictMode.enterCriticalSpan("ScrollView-scroll"); } break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: /* Release the drag */ mIsBeingDragged = false; mActivePointerId = INVALID_POINTER; recycleVelocityTracker(); if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) { postInvalidateOnAnimation(); } break; case MotionEvent.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; } /* * The only time we want to intercept motion events is if we are in the * drag mode. */ return mIsBeingDragged; } ~~~ 其實大家只要知道這個方法是事件攔截就行了，關于他的具體機制去看看這篇博客[點擊打開鏈接](http://blog.csdn.net/chunqiuwei/article/details/41084921)，寫得很詳細，好了我們接下來就要在我們的自定義組件中覆寫這個方法就行了，一切就是這么簡單。我實現的是在scrollview中嵌套一個橫向滑動的ListView，先來看看我復寫的ScrollView： ~~~ import android.content.Context; import android.util.AttributeSet; import android.view.MotionEvent; import android.widget.ScrollView; public class MyScrollView extends ScrollView { private float mDX, mDY, mLX, mLY; int mLastAct = -1; boolean mIntercept = false; public MyScrollView(Context context, AttributeSet attrs) { super(context, attrs); // TODO Auto-generated constructor stub } public MyScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // TODO Auto-generated constructor stub } public MyScrollView(Context context) { super(context); // TODO Auto-generated constructor stub } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN : mDX = mDY = 0f; mLX = ev.getX(); mLY = ev.getY(); break; case MotionEvent.ACTION_MOVE : final float curX = ev.getX(); final float curY = ev.getY(); mDX += Math.abs(curX - mLX); mDY += Math.abs(curY - mLY); mLX = curX; mLY = curY; if (mIntercept && mLastAct == MotionEvent.ACTION_MOVE) { return false; } if (mDX > mDY) { mIntercept = true; mLastAct = MotionEvent.ACTION_MOVE; return false; } } mLastAct = ev.getAction(); mIntercept = false; return super.onInterceptTouchEvent(ev);} ~~~ 好了，接下來我為大家詳細講解這個方法的具體含義；首先，這方法是View的事件攔截，如果返回true的話，說明觸摸事件（包括DOWN,MOVE,UP）不會往下面傳遞，就在該view上面處理了，怎么理解呢？例如我的ScrollView是A ,橫向的ListView是B,?? B包含在A中，B是A的子view。那么觸摸事件是先讓A判斷了，然后再傳給B。如果在A中實現上面那個事件攔截事件，在特定情況下才將事件傳給B處理，如果不是B的事件，那個A就不會傳給B，這樣A和B就分離開了。其中 ~~~ if (mDX > mDY) ?{ mIntercept = true; mLastAct = MotionEvent.ACTION_MOVE; return false; } ~~~ 就是判斷手指在屏幕上面滑動的方向，這里判斷出是在橫向上面滑動，那么就返回false，表示不攔截這個事件，這個事件就會傳到B，讓B來處理這個事件，剛好B是橫向的Listview，就會對橫向方向的滑動事件進行處理。如果手指滑動的方向不是橫向，就supper父類的默認攔截事件。這里就相當于給攔截事件增加了一些判斷，而增加的判斷無非就是手指的滑動方向，ListView或ScrollView都是豎向的，而橫向的ListView和橫向滑動的Veiwpager是橫向的，不管是誰嵌套誰，只需要在重寫第一個View，把它的 ~~~ public boolean onInterceptTouchEvent(MotionEvent ev) ~~~ 方法重新寫一下，就可以解決手勢沖突的問題！希望對大家的學習和工作有所幫助，謝謝！