Android实现滑动选择控件实例代码

前言

最近做了个滑动选择的小控件，拿出来给大家分享一下，先上图

运行效果

实现步骤

这里分解为3个动作:Down、Move、Up来进行分析，博主文采不好，大家直接看流程图吧！！

代码分析

前置知识

1、这个地方使用的是RecyclerView的代码，使用RecyclerView只能使用LinearLayoutManager,ListView的运行效果稍微要比RecyclerView差一些

//这里使用dispatchTouchEvent，因为onTouchEvent容易被OnTouchListener截取
  @Override
  public boolean dispatchTouchEvent(MotionEvent ev) {
    LayoutManager manager = getLayoutManager();
    //获取第一个和最后一个显示的Item对应的相对Position
    if (manager instanceof LinearLayoutManager) {
      mFirstVisiblePosition = ((LinearLayoutManager) manager).findFirstVisibleItemPosition();
      mLastVisiblePosition = ((LinearLayoutManager) manager).findLastVisibleItemPosition();
    }
    switch (ev.getAction()) {
      case MotionEvent.ACTION_DOWN:
 //获取按下时的位置,x,y
 int startX = (int) ev.getX();
 int startY = (int) ev.getY();
 int preX = startX;
 mPreY = startY;
 mPreFirstVisiblePosition = mFirstVisiblePosition;
 mPrePosition = mStartPosition = pointToPosition(startX, startY);

 if (mStartPosition > -1) {
   //获取当前Item的View
   View child = getChildAt(mStartPosition);
   if (null != child) {
     //获取响应域，一般响应域里面就是一个CheckBox
     View tmpCheckBoxContainer = child.findViewWithTag("checkbox_layout");
     if (null != tmpCheckBoxContainer && tmpCheckBoxContainer.getVisibility() == VISIBLE) {
mCheckBoxWidth = tmpCheckBoxContainer.getWidth();
//获取响应域的范围，一定要用这种获取绝对位置的方式，不然会受到padding或者是margin的影响
int[] location = new int[2];
tmpCheckBoxContainer.getLocationOnScreen(location);
mCheckBoxX = location[0];
//判断按下的位置是否是在响应域内
if (startX >= mCheckBoxX && startX <= (mCheckBoxX + mCheckBoxWidth)) {
  Log.d(LOG_TAG, "dispatchTouchEvent() DOWN mStartPosition: " + mStartPosition);
  //设置截取事件的标志位
  mIsNeedScrollCheck = true;
  //设置为第一次滑动，这是用作判断折返的
  mIsFirstMove = true;
  setStartCheckBoxState();
  //截获Checkbox的点击事件，防止两次选中
  return true;
} else {
  mIsNeedScrollCheck = false;
}
     } else {
mIsNeedScrollCheck = false;
Log.e(LOG_TAG, "dispatchTouchEvent() ", new Throwable("Cannot get CheckBoxContainer!"));
     }

   } else {
     Log.e(LOG_TAG, "dispatchTouchEvent() ", new Throwable("Cannot get item view!"));
   }
 }
 break;
      case MotionEvent.ACTION_MOVE:
 //获取当前位置
 int currentX = (int) ev.getX();
 int currentY = (int) ev.getY();
 //获取当前的item
 int currentPosition = pointToPosition(currentX, currentY);
 //判断是否允许滑动选中
 if (mIsNeedScrollCheck && -1 != mFirstVisiblePosition && -1 != mLastVisiblePosition && -1 != currentPosition) {
   //判断是否在下一个Item的像英语
   if ((currentPosition + mFirstVisiblePosition) != (mPrePosition + mPreFirstVisiblePosition) &&
currentX >= mCheckBoxX && currentX <= (mCheckBoxX + mCheckBoxWidth)) {

     Log.i(LOG_TAG, "********************************** dispatchTouchEvent() ********************************");
     Log.d(LOG_TAG, "dispatchTouchEvent() MOVE mCurrentPosition: " + currentPosition);
     Log.d(LOG_TAG, "dispatchTouchEvent() MOVE mFirstVisiblePosition: " + mFirstVisiblePosition);
     Log.d(LOG_TAG, "dispatchTouchEvent() MOVE mPrePosition: " + mPrePosition);
     Log.d(LOG_TAG, "dispatchTouchEvent() MOVE mPreFirstVisiblePosition: " + mPreFirstVisiblePosition);
     Log.i(LOG_TAG, "********************************** dispatchTouchEvent() ********************************");

     //折返回来时要改变前一个的Checkbox的状态

     if (mIsFirstMove) {
mIsFirstMove = false;
if (currentY >= mPreY) {
  mUpOrDown = false;
} else {
  mUpOrDown = true;
}
     } else {
if ((currentPosition + mFirstVisiblePosition) > (mPrePosition + mPreFirstVisiblePosition) && mUpOrDown) {
  changeCheckBoxState(mPrePosition);
  mUpOrDown = false;
} else if ((currentPosition + mFirstVisiblePosition) < (mPrePosition + mPreFirstVisiblePosition) && !mUpOrDown) {
  changeCheckBoxState(mPrePosition);
  mUpOrDown = true;
}
     }


     changeCheckBoxState(currentPosition);

   }

   //判断是否是在最后一个item上滑动，如果是则进行自动向下滑动，如果是在第一个上下滑动，则自动向上滑动
   //Log.d(LOG_TAG, "dispatchTouchEvent() MOVE: " + (mLastVisiblePosition - mCurrentPosition - mFirstVisiblePosition));
   if ((mLastVisiblePosition - mFirstVisiblePosition - currentPosition) < 1 && currentY > mPreY) {
     //自动向下滑
     Log.d(LOG_TAG, "dispatchTouchEvent() MOVE mCount: " + mCount);
     View child = getChildAt(currentPosition);
     if (null != child && 0 == mCount % 5) {
scrollToPosition(mLastVisiblePosition + 1);
     }
     mCount++;
   } else if (currentPosition < 2 && currentY < mPreY) {
     //自动向上滑
     View child = getChildAt(currentPosition);
     Log.d(LOG_TAG, "dispatchTouchEvent() MOVE mCount: " + mCount);
     //mCount用于降低滑动的频率，频率太快容易滑动的看不清楚
     if (null != child && 0 == mCount % 5) {
scrollToPosition(mFirstVisiblePosition - 1);
     }
     mCount++;
   }
   mPreY = currentY;
   mPrePosition = currentPosition;
   mPreFirstVisiblePosition = mFirstVisiblePosition;

   return true;
 }
 break;

      case MotionEvent.ACTION_UP:
 if (mIsNeedScrollCheck) {
   mCount = 0;
   return false;

 }
 break;


    }
    return super.dispatchTouchEvent(ev);
  }

其他的代码片段

//改变开始的CheckBox状态
  private void setStartCheckBoxState() {
    View child = getChildAt(mStartPosition);
    if (null != child) {
      ViewGroup checkBoxContainer = (ViewGroup) child.findViewWithTag("checkbox_layout");
      if (null != checkBoxContainer) {
 CheckBox checkBox = (CheckBox) checkBoxContainer.getChildAt(0);
 if (null != checkBox && checkBox.getVisibility() == VISIBLE) {
   checkBox.toggle();
 }
      }

    }
  }

//判断当前Item的Position，相对位置
  private int pointToPosition(int x, int y) {
    Rect frame = mTouchframe;
    if (frame == null) {
      mTouchframe = new Rect();
      frame = mTouchframe;
    }

    final int count = getChildCount();
    for (int i = count - 1; i >= 0; i--) {
      final View child = getChildAt(i);
      if (child.getVisibility() == View.VISIBLE) {
 child.getHitRect(frame);
 if (frame.contains(x, y)) {
   return i;
 }
      }
    }
    return -1;
  }

//改变Position的选中状态
  public void changeCheckBoxState(int position) {
    if (position < 0 || position >= getChildCount()) {
      return;
    }

    View child = getChildAt(position);
    if (null != child) {
      ViewGroup checkBoxLayout = (ViewGroup) child.findViewWithTag("checkbox_layout");
      if (null != checkBoxLayout && checkBoxLayout.getVisibility() == VISIBLE) {
 CheckBox checkBox = (CheckBox) checkBoxLayout.getChildAt(0);
 if (null != checkBox) {
   Log.d(LOG_TAG, "changeCheckBoxState() selectCheckBox: " + position);
   //checkBox.performClick();
   checkBox.toggle();
   //checkBox.setClickable(false);
   //checkBox.callonClick();
 }
      }

    }
  }

项目源码：ScrollCheckBox_jb51.rar

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