SlidingCheckLayout是一个滑动选中RecyclerView中Item的布局，手指滑过Item时多项选中。
作者：竹尘居士
github：https://github.com/homgwu/SlidingCheckLayout
示例
特性
SlidingCheckLayout继承自FrameLayout，使用时把RecyclerView放在SlidingCheckLayout里层。
左右滑动时手指滑到某项即回调该项的Position，上下滑动时根据position，回调开始和结束的position。
长按进入滑选模式。
实现方式
-
在dispatchTouchEvent中检测长按和处理滑动的位置：
@Override
public boolean dispatchTouchEvent(MotionEvent event) {if (!isSlidingEnable() || !isEnabled()) {return super.dispatchTouchEvent(event);
}
if (!isCanIntercept()) {return super.dispatchTouchEvent(event);
}
final int action = event.getActionMasked();
switch (action) {case MotionEvent.ACTION_DOWN:
// Log.i(TAG, "dispatchTouchEvent ACTION_DOWN mStartingCheck:" + mStartingCheck);
mInitDownY = mLastY = event.getY();
mInitDownX = mLastX = event.getX();
checkForLongClick(0, mInitDownX, mInitDownY);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
// Log.i(TAG, "dispatchTouchEvent ACTION_CANCEL||ACTION_UP mStartingCheck:" + mStartingCheck);
removeLongPressCallback();
mLastPosition = RecyclerView.NO_POSITION;
mIncrease = 0;
if (mStartingCheck) {mStartingCheck = false;
return true;
}
break;
case MotionEvent.ACTION_MOVE:
// Log.i(TAG, "dispatchTouchEvent ACTION_MOVE mStartingCheck:" + mStartingCheck);
float y = event.getY();
float x = event.getX();
final float yInitDiff = y - mInitDownY;
final float xInitDiff = x - mInitDownX;
mLastY = y;
mLastX = x;
if (!mStartingCheck && (Math.abs(yInitDiff) > mTouchSlop || Math.abs(xInitDiff) > mTouchSlop)) {removeLongPressCallback();
}
if (mStartingCheck) {checkSlidingPosition(x, y);
return true;
}
break;
}
boolean result = super.dispatchTouchEvent(event);
// Log.i(TAG, "dispatchTouchEvent super.dispatchTouchEvent result:" + result);
return result;
}
为何要在dispatchTouchEvent中处理而不在onInterceptTouchEvent和onTouchEvent中处理呢，因为如果是一些复杂的界面，SlidingCheckLayout的某上层还有可以滑动的布局如RecyclerView,ViewPager，他们可能会在Down或Move你返回false，里层RecyclerView也返回false时截断事件(而你又不能直接都返回True，在没进入滑选模式时要保证里层的RecyclerView还可以响应点击等事件)，那么SlidingCheckLayout会收不到后续的事件，而dispatchTouchEvent方法可以在SlidingCheckLayout不截断事件的情况下每次被调用到(询问是否要截断或分发到里层)。
为何要在ACTION_UP时返回true，因为如果不在up时返回true那么这个up事件可能会被里层的RecyclerView响应成点击事件而多次处理点击的这个item。
-
长按处理：
检查长按和移除(长按的代码是从View长按源码中copy出来改改的)，
private void checkForLongClick(int delayOffset, float x, float y) {if (mPendingCheckForLongPress == null) {mPendingCheckForLongPress = new CheckForLongPress();
}
mPendingCheckForLongPress.setAnchor(x, y);
mPendingCheckForLongPress.rememberPressedState();
mHandler.postDelayed(mPendingCheckForLongPress,
sLongPressTime - delayOffset);
}
private void removeLongPressCallback() {if (mPendingCheckForLongPress != null) {mHandler.removeCallbacks(mPendingCheckForLongPress);
}
}
进入长按：
private final class CheckForLongPress implements Runnable {private float mX;
private float mY;
private boolean mOriginalPressedState;
@Override
public void run() {if ((mOriginalPressedState == isPressed()) && (mLastPosition = checkDownPosition(mX, mY)) != RecyclerView.NO_POSITION) {if (mOnSlidingPositionListener != null) {mOnSlidingPositionListener.onSlidingPosition(mLastPosition);
}
requestDisallowInterceptTouchEvent(true);
mStartingCheck = true;
}
}
public void setAnchor(float x, float y) {mX = x;
mY = y;
}
public void rememberPressedState() {mOriginalPressedState = isPressed();
}
}
-
检查滑过的是哪个item，并回调position
private void checkSlidingPosition(float x, float y) {View childViewUnder = mTargetRv.findChildViewUnder(x, y);
if (mOnSlidingPositionListener == null || childViewUnder == null) return;
int currentPosition = mTargetRv.getChildAdapterPosition(childViewUnder);
// Log.w(TAG, "checkSlidingPosition currentPosition:" + currentPosition + ",mLastPosition:" + mLastPosition);
if (currentPosition == mLastPosition || currentPosition == RecyclerView.NO_POSITION) return;
if (mLastPosition != RecyclerView.NO_POSITION && Math.abs(currentPosition - mLastPosition) > 1) {if (mLastPosition > currentPosition) {mOnSlidingPositionListener.onSlidingRangePosition(currentPosition, mIncrease > 0 ? mLastPosition : mLastPosition - 1);
} else {mOnSlidingPositionListener.onSlidingRangePosition(mIncrease < 0 ? mLastPosition : mLastPosition + 1, currentPosition);
}
} else {if ((mIncrease > 0 && mLastPosition > currentPosition) || (mIncrease < 0 && currentPosition > mLastPosition)) {mOnSlidingPositionListener.onSlidingPosition(mLastPosition);
}
mOnSlidingPositionListener.onSlidingPosition(currentPosition);
}
mIncrease = currentPosition > mLastPosition ? 1 : -1;
mLastPosition = currentPosition;
}
通过RecyclerView的findChildViewUnder方法用坐标找到对应的子View，再getChildAdapterPosition就可以得到子View的位置了。
使用方法
-
布局:
<?xml version="1.0" encoding="utf-8"?>
<com.homg.scl.SlidingCheckLayout
android:id="@+id/scl"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/reminder_tv">
<android.support.v7.widget.RecyclerView
android:id="@+id/rv"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</com.homg.scl.SlidingCheckLayout>
-
设置Listener:
mSlidingCheckLayout.setOnSlidingPositionListener(this);
@Override
public void onSlidingPosition(int position) {MainEntity entity = mMainRvAdapter.getEntityByPosition(position);
entity.setSelect(!entity.isSelect());
mMainRvAdapter.notifyItemChanged(position);
}
@Override
public void onSlidingRangePosition(int startPosition, int endPosition) {for (int i = startPosition; i <= endPosition; i++) {MainEntity entity = mMainRvAdapter.getEntityByPosition(i);
entity.setSelect(!entity.isSelect());
}
mMainRvAdapter.notifyItemRangeChanged(startPosition, endPosition - startPosition + 1);
}