ViewDragHelper

最新推荐文章于 2025-05-17 14:03:41 发布

原创最新推荐文章于 2025-05-17 14:03:41 发布 · 300 阅读

CC 4.0 BY-SA版权

本文介绍了一个自定义的DragViewGroup组件实现方法，该组件使用ViewDragHelper处理视图的拖拽操作。通过覆盖关键的方法如onInterceptTouchEvent和onTouchEvent来实现视图的拖拽效果，并详细展示了如何初始化和配置ViewDragHelper。

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import android.content.Context;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;

/**
 * Created by Administrator on 2015/12/17.
 */
public class DragViewGroup extends FrameLayout {

    private ViewDragHelper mViewDragHelper;
    private View mMenuView,mMainView;
    private int mWtdth;

    public DragViewGroup(Context context) {
        super(context);
        initView();
    }

    public DragViewGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    public DragViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView();
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        mMenuView = getChildAt(0);
        mMainView = getChildAt(1);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mWtdth = mMenuView.getMeasuredWidth();
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return mViewDragHelper.shouldInterceptTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        mViewDragHelper.processTouchEvent(event);
        return true;
    }

    public void initView(){
        mViewDragHelper = ViewDragHelper.create(this,callback);
    }

    private ViewDragHelper.Callback callback = new ViewDragHelper.Callback() {
        @Override
        public boolean tryCaptureView(View child, int pointerId) {
            return mMainView == child;
        }

        @Override
        public int clampViewPositionVertical(View child, int top, int dy) {
            return 0;
        }

        @Override
        public int clampViewPositionHorizontal(View child, int left, int dx) {
            return left;
        }

        @Override
        public void onViewReleased(View releasedChild, float xvel, float yvel) {
            super.onViewReleased(releasedChild, xvel, yvel);
            if(mMainView.getLeft() < 500){
                mViewDragHelper.smoothSlideViewTo(mMainView,0,0);
                ViewCompat.postInvalidateOnAnimation(DragViewGroup.this);
            }else{
                mViewDragHelper.smoothSlideViewTo(mMainView,300,0);
                ViewCompat.postInvalidateOnAnimation(DragViewGroup.this);
            }
        }
    };

    @Override
    public void computeScroll() {
        if(mViewDragHelper.continueSettling(true)){
            ViewCompat.postInvalidateOnAnimation(this);
        }
    }
}