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
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。