ViewDrawHelper实现滑动删除

package org.itheima62.sweep;import org.itheima62.sweep.SweepView.OnSweepListener;import android.content.Context;import android.support.v4.view.ViewCompat;import android.support.v4.widget.ViewDragHelper;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;public class SweepView extends ViewGroup {   private static final String TAG = "SweepView";   private View mContentView;   private View mDeleteView;   private int mDeleteWidth;   private ViewDragHelper mHelper;   private boolean isOpened;   private OnSweepListener mListener;   public SweepView(Context context) {      this(context, null);   }   public SweepView(Context context, AttributeSet attrs) {      super(context, attrs);      mHelper = ViewDragHelper.create(this, new MyCallBack());   }   @Override   protected void onFinishInflate() {      mContentView = getChildAt(0);      mDeleteView = getChildAt(1);      LayoutParams params = mDeleteView.getLayoutParams();      mDeleteWidth = params.width;   }   @Override   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {      measureChildren(widthMeasureSpec, heightMeasureSpec);      super.onMeasure(widthMeasureSpec, heightMeasureSpec);   /* // 测量内容      mContentView.measure(widthMeasureSpec, heightMeasureSpec);      // 测量删除部分      int deleteWidthMeasureSpec = MeasureSpec.makeMeasureSpec(mDeleteWidth,            MeasureSpec.EXACTLY);      mDeleteView.measure(deleteWidthMeasureSpec, heightMeasureSpec);      // 确定自己的高度      int width = MeasureSpec.getSize(widthMeasureSpec);      int height = MeasureSpec.getSize(heightMeasureSpec);      setMeasuredDimension(width, height);*/   }   @Override   protected void onLayout(boolean changed, int l, int t, int r, int b) {      // 布局孩子      // 布局内容区域      mContentView.layout(0, 0, mContentView.getMeasuredWidth(),            mContentView.getMeasuredHeight());      // 布局删除的部分      mDeleteView.layout(mContentView.getMeasuredWidth(), 0,            mContentView.getMeasuredWidth() + mDeleteWidth,            mDeleteView.getMeasuredHeight());   }   @Override   public boolean onTouchEvent(MotionEvent event) {      mHelper.processTouchEvent(event);      return true;   }   class MyCallBack extends ViewDragHelper.Callback {      // 是否分析view的touch      @Override      public boolean tryCaptureView(View child, int pointerId) {         // child:触摸的view         // pointerId：touch的id         Log.d(TAG, (child == mContentView) + "");         // 去分析child         return child == mContentView || child == mDeleteView;      }      @Override      public int clampViewPositionHorizontal(View child, int left, int dx) {         // 当touch移动后的回调         // @child : 谁移动了         // @left: child的左侧的边距         // @dx: 增量的x         if (child == mContentView) {            if (left < 0 && -left > mDeleteWidth) {               return -mDeleteWidth;            } else if (left > 0) {               return 0;            }         } else if (child == mDeleteView) {            int measuredWidth = mContentView.getMeasuredWidth();            if (left < measuredWidth - mDeleteWidth) {               return measuredWidth - mDeleteWidth;            } else if (left > measuredWidth) {               return measuredWidth;            }         }         // 确定要移动多少         return left;      }      @Override      public void onViewPositionChanged(View changedView, int left, int top,            int dx, int dy) {         // 当控件位置移动时的回调         // @changedView: 哪个view移动了         // @left,top:view的左上角的坐标         // @dx,dy: 移动的增量         ViewCompat.postInvalidateOnAnimation(SweepView.this);         int contentWidth = mContentView.getMeasuredWidth();         int contentHeight = mContentView.getMeasuredHeight();         int deleteHeight = mDeleteView.getMeasuredHeight();         if (changedView == mContentView) {            // 如果移动的是内容的view            mDeleteView.layout(contentWidth + left, 0, contentWidth + left                  + mDeleteWidth, deleteHeight);         } else if (changedView == mDeleteView) {            mContentView                  .layout(left - contentWidth, 0, left, contentHeight);         }      }      @Override      public void onViewReleased(View releasedChild, float xvel, float yvel) {         // up时的回调         // @releasedChild:松开了哪个view         // @xvel,yvel:速率         int left = mContentView.getLeft();         if (-left < mDeleteWidth / 2f) {            // 关闭            close();         } else {            // 打开            open();         }         // invalidate();      }   }   public void open() {      isOpened = true;      if (mListener != null) {         mListener.onSweepChanged(SweepView.this, isOpened);      }      int contentWidth = mContentView.getMeasuredWidth();      int contentHeight = mContentView.getMeasuredHeight();      int deleteHeight = mDeleteView.getMeasuredHeight();      // // 布局内容区域      // mContentView.layout(-mDeleteWidth, 0, contentWidth      // - mDeleteWidth, mContentView.getMeasuredHeight());      //      // // 布局删除的部分      // mDeleteView.layout(contentWidth - mDeleteWidth, 0,      // contentWidth, mDeleteView.getMeasuredHeight());      // 数据的模拟      mHelper.smoothSlideViewTo(mContentView, -mDeleteWidth, 0);      mHelper.smoothSlideViewTo(mDeleteView, contentWidth - mDeleteWidth, 0);      ViewCompat.postInvalidateOnAnimation(SweepView.this);   }   public void close() {      isOpened = false;      if (mListener != null) {         mListener.onSweepChanged(SweepView.this, isOpened);      }      // // 布局内容区域      // mContentView.layout(0, 0, mContentView.getMeasuredWidth(),      // mContentView.getMeasuredHeight());      //      // // 布局删除的部分      // mDeleteView.layout(mContentView.getMeasuredWidth(), 0,      // mContentView.getMeasuredWidth() + mDeleteWidth,      // mDeleteView.getMeasuredHeight());      // 数据的模拟      mHelper.smoothSlideViewTo(mContentView, 0, 0);      mHelper.smoothSlideViewTo(mDeleteView, mContentView.getMeasuredWidth(),            0);      ViewCompat.postInvalidateOnAnimation(SweepView.this);   }   @Override   public void computeScroll() {      if (mHelper.continueSettling(true)) {         ViewCompat.postInvalidateOnAnimation(SweepView.this);      }   }   public void setOnSweepListener(OnSweepListener listener) {      this.mListener = listener;   }   public interface OnSweepListener {      void onSweepChanged(SweepView view, boolean isOpened);   }}