package com.zhy.blogcodes.vdh;
import android.content.Context;
import android.graphics.Point;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.LinearLayout;
/**
* Created by zhy on 15/6/3.
*/
public class VDHLayout extends LinearLayout
{
private ViewDragHelper mDragger;
private View mDragView;
private View mAutoBackView;
private View mEdgeTrackerView;
private Point mAutoBackOriginPos = new Point();
public VDHLayout(Context context, AttributeSet attrs)
{
super(context, attrs);
mDragger = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback()
{
@Override
public boolean tryCaptureView(View child, int pointerId)
{
//mEdgeTrackerView禁止直接移动
return child == mDragView || child == mAutoBackView;
}
@Override
public int clampViewPositionHorizontal(View child, int left, int dx)
{
return left;
}
@Override
public int clampViewPositionVertical(View child, int top, int dy)
{
return top;
}
//手指释放的时候回调
@Override
public void onViewReleased(View releasedChild, float xvel, float yvel)
{
//mAutoBackView手指释放时可以自动回去
if (releasedChild == mAutoBackView)
{
mDragger.settleCapturedViewAt(mAutoBackOriginPos.x, mAutoBackOriginPos.y);
invalidate();
}
}
//在边界拖动时回调
@Override
public void onEdgeDragStarted(int edgeFlags, int pointerId)
{
mDragger.captureChildView(mEdgeTrackerView, pointerId);
}
@Override
public int getViewHorizontalDragRange(View child)
{
return getMeasuredWidth()-child.getMeasuredWidth();
}
@Override
public int getViewVerticalDragRange(View child)
{
return getMeasuredHeight()-child.getMeasuredHeight();
}
});
mDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_LEFT);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event)
{
return mDragger.shouldInterceptTouchEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
mDragger.processTouchEvent(event);
return true;
}
@Override
public void computeScroll()
{
if(mDragger.continueSettling(true))
{
invalidate();
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
super.onLayout(changed, l, t, r, b);
mAutoBackOriginPos.x = mAutoBackView.getLeft();
mAutoBackOriginPos.y = mAutoBackView.getTop();
}
@Override
protected void onFinishInflate()
{
super.onFinishInflate();
mDragView = getChildAt(0);
mAutoBackView = getChildAt(1);
mEdgeTrackerView = getChildAt(2);
}
}