android view 随意滑动 android 拖动view

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墨染心语 2023-07-31 17:51:52

文章标签 android view 随意滑动 android java 自定义View 可拖拽的GridView 文章分类 Android 移动开发

效果图

android view 随意滑动 android 拖动view_android view 随意滑动

思路分析

新建一个类继承于GridView

public class DragGridView extends GridView

既然是自定义view,那就疯狂得DIY,花样肯定要整起来

既然是推拽，肯定要选择一个国际通用的触发方式——长按啦

既然是长按肯定要有个长按响应的时间

震动器也要加上，增强互交感变量的注释写再上面

/**
     * DragGridView的item长按响应的时间， 默认是1000毫秒，也可以自行设置
     */
    private long dragResponseMS = 1000;
    /**
     * 是否可以拖拽，默认不可以
     */
    private boolean isDrag = false;
    private int mDownX;
    private int mDownY;
    private int moveX;
    private int moveY;
    /**
     * 正在拖拽的position
     */
    private int mDragPosition;
    /**
     * 刚开始拖拽的item对应的View
     */
    private View mStartDragItemView = null;
    /**
     * 用于拖拽的镜像，这里直接用一个ImageView
     */
    private ImageView mDragImageView;
    /**
     * 震动器
     */
    private Vibrator mVibrator;
    private WindowManager mWindowManager;
    /**
     * item镜像的布局参数
     */
    private WindowManager.LayoutParams mWindowLayoutParams;
    /**
     * 我们拖拽的item对应的Bitmap
     */
    private Bitmap mDragBitmap;
    /**
     * 按下的点到所在item的上边缘的距离
     */
    private int mPoint2ItemTop ; 
    /**
     * 按下的点到所在item的左边缘的距离
     */
    private int mPoint2ItemLeft;
    /**
     * DragGridView距离屏幕顶部的偏移量
     */
    private int mOffset2Top;
    /**
     * DragGridView距离屏幕左边的偏移量
     */
    private int mOffset2Left;
    /**
     * 状态栏的高度
     */
    private int mStatusHeight; 
    /**
     * DragGridView自动向下滚动的边界值
     */
    private int mDownScrollBorder;
    /**
     * DragGridView自动向上滚动的边界值
     */
    private int mUpScrollBorder;
    
    /**
     * DragGridView自动滚动的速度
     */
    private static final int speed = 80;
    
    /**
     * item发生变化回调的接口
     */
    private OnChanageListener onChanageListener;

初始化

在DragGridView(Context context, AttributeSet attrs, int defStyle)下

初始化震动器

mVibrator = (Vibrator) context.getSystemService(Context.VIBRATOR_SERVICE);

获取状态栏的高度

mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        mStatusHeight = getStatusHeight(context);

用来处理是否为长按的Runnable

调用Vibrator.vibrate(int i);可以在里面实现震动效果

private Runnable mLongClickRunnable = new Runnable() {
        @Override
        public void run() {
            isDrag = true; //设置可以拖拽
            mVibrator.vibrate(50); //震动一下
            mStartDragItemView.setVisibility(View.INVISIBLE);//隐藏该item            
            //根据我们按下的点显示item镜像
            createDragImage(mDragBitmap, mDownX, mDownY);
        }
    };

拦截触摸事件

这里简单说下MotionEvent

事件	简介
ACTION_DOWN	手指初次接触到屏幕时触发。
ACTION_MOVE	手指在屏幕上滑动时触发，会多次触发。
ACTION_UP	手指离开屏幕时触发。
ACTION_CANCEL	事件被上层拦截时触发。
ACTION_OUTSIDE	手指不在控件区域时触发。

移动之前要判断是否点击在GridView的item上面

/**
     * 是否点击在GridView的item上面
     * @param itemView
     * @param x
     * @param y
     * @return
     */
    private boolean isTouchInItem(View dragView, int x, int y){
        int leftOffset = dragView.getLeft();
        int topOffset = dragView.getTop();
        if(x < leftOffset || x > leftOffset + dragView.getWidth()){
            return false;
        }
        
        if(y < topOffset || y > topOffset + dragView.getHeight()){
            return false;
        }
        
        return true;
    }

@Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        switch(ev.getAction()){
        case MotionEvent.ACTION_DOWN:
            //使用Handler延迟dragResponseMS执行mLongClickRunnable
            mHandler.postDelayed(mLongClickRunnable, dragResponseMS);
            
            mDownX = (int) ev.getX();
            mDownY = (int) ev.getY();
            
            //根据按下的X,Y坐标获取所点击item的position
            mDragPosition = pointToPosition(mDownX, mDownY);
            
            if(mDragPosition == AdapterView.INVALID_POSITION){
                return super.dispatchTouchEvent(ev);
            }
            
            //根据position获取该item所对应的View
            mStartDragItemView = getChildAt(mDragPosition - getFirstVisiblePosition());
            
            //下面这几个距离大家可以参考我的博客上面的图来理解下
            mPoint2ItemTop = mDownY - mStartDragItemView.getTop();
            mPoint2ItemLeft = mDownX - mStartDragItemView.getLeft();
            
            mOffset2Top = (int) (ev.getRawY() - mDownY);
            mOffset2Left = (int) (ev.getRawX() - mDownX);
            
            //获取DragGridView自动向上滚动的偏移量，小于这个值，DragGridView向下滚动
            mDownScrollBorder = getHeight() /4;
            //获取DragGridView自动向下滚动的偏移量，大于这个值，DragGridView向上滚动
            mUpScrollBorder = getHeight() * 3/4;        
            //开启mDragItemView绘图缓存
            mStartDragItemView.setDrawingCacheEnabled(true);
            //获取mDragItemView在缓存中的Bitmap对象
            mDragBitmap = Bitmap.createBitmap(mStartDragItemView.getDrawingCache());
            //这一步很关键，释放绘图缓存，避免出现重复的镜像
            mStartDragItemView.destroyDrawingCache();            
            break;
        case MotionEvent.ACTION_MOVE:
            int moveX = (int)ev.getX();
            int moveY = (int) ev.getY();
            
            //如果我们在按下的item上面移动，只要不超过item的边界我们就不移除mRunnable
            if(!isTouchInItem(mStartDragItemView, moveX, moveY)){
                mHandler.removeCallbacks(mLongClickRunnable);
            }
            break;
        case MotionEvent.ACTION_UP:
            mHandler.removeCallbacks(mLongClickRunnable);
            mHandler.removeCallbacks(mScrollRunnable);
            break;
        }
        return super.dispatchTouchEvent(ev);
    }
        
        @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if(isDrag && mDragImageView != null){
            switch(ev.getAction()){
            case MotionEvent.ACTION_MOVE:
                moveX = (int) ev.getX();
                moveY = (int) ev.getY();
                //拖动item
                onDragItem(moveX, moveY);
                break;
            case MotionEvent.ACTION_UP:
                onStopDrag();
                isDrag = false;
                break;
            }
            return true;
        }
        return super.onTouchEvent(ev);
    }

优化视觉体验

拖动过程中要实现拖动的镜像

/**
     * 创建拖动的镜像
     * @param bitmap 
     * @param downX
     *             按下的点相对父控件的X坐标
     * @param downY
     *             按下的点相对父控件的X坐标
     */
    private void createDragImage(Bitmap bitmap, int downX , int downY){
        mWindowLayoutParams = new WindowManager.LayoutParams();
        mWindowLayoutParams.format = PixelFormat.TRANSLUCENT; //图片之外的其他地方透明
        mWindowLayoutParams.gravity = Gravity.TOP | Gravity.LEFT;
        mWindowLayoutParams.x = downX - mPoint2ItemLeft + mOffset2Left;
        mWindowLayoutParams.y = downY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
        mWindowLayoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT;  
        mWindowLayoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;  
        mWindowLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE  
                    | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE ;
          
        mDragImageView = new ImageView(getContext());  
        mDragImageView.setImageBitmap(bitmap);  
        mWindowManager.addView(mDragImageView, mWindowLayoutParams);  
    }

要想拖动的item实现半透明效果就加上

mWindowLayoutParams.alpha = 0.55f; //透明度

/**
     * 从界面上面移动拖动镜像
     */
    private void removeDragImage(){
        if(mDragImageView != null){
            mWindowManager.removeView(mDragImageView);
            mDragImageView = null;
        }
    }
    
    /**
     * 拖动item，在里面实现了item镜像的位置更新，item的相互交换以及GridView的自行滚动
     * @param x
     * @param y
     */
    private void onDragItem(int moveX, int moveY){
        mWindowLayoutParams.x = moveX - mPoint2ItemLeft + mOffset2Left;
        mWindowLayoutParams.y = moveY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
        mWindowManager.updateViewLayout(mDragImageView, mWindowLayoutParams); //更新镜像的位置
        onSwapItem(moveX, moveY);
        
        //GridView自动滚动
        mHandler.post(mScrollRunnable);
    }
    
    
    /**
     * 当moveY的值大于向上滚动的边界值，触发GridView自动向上滚动
     * 当moveY的值小于向下滚动的边界值，触犯GridView自动向下滚动
     * 否则不进行滚动
     */
    private Runnable mScrollRunnable = new Runnable() {
        
        @Override
        public void run() {
            int scrollY;
            if(moveY > mUpScrollBorder){
                 scrollY = -speed;
                 mHandler.postDelayed(mScrollRunnable, 25);
            }else if(moveY < mDownScrollBorder){
                scrollY = speed;
                 mHandler.postDelayed(mScrollRunnable, 25);
            }else{
                scrollY = 0;
                mHandler.removeCallbacks(mScrollRunnable);
            }
            
            //当我们的手指到达GridView向上或者向下滚动的偏移量的时候，可能我们手指没有移动，但是DragGridView在自动的滚动
            //所以我们在这里调用下onSwapItem()方法来交换item
            onSwapItem(moveX, moveY);
            
            View view = getChildAt(mDragPosition - getFirstVisiblePosition());
            //实现GridView的自动滚动
            smoothScrollToPositionFromTop(mDragPosition, view.getTop() + scrollY);
        }
    };
    
    /**
     * 交换item,并且控制item之间的显示与隐藏效果
     * @param moveX
     * @param moveY
     */
    private void onSwapItem(int moveX, int moveY){
        //获取我们手指移动到的那个item的position
        int tempPosition = pointToPosition(moveX, moveY);
        //假如tempPosition 改变了并且tempPosition不等于-1,则进行交换
        if(tempPosition != mDragPosition && tempPosition != AdapterView.INVALID_POSITION){
            getChildAt(tempPosition - getFirstVisiblePosition()).setVisibility(View.INVISIBLE);//拖动到了新的item,新的item隐藏掉
            getChildAt(mDragPosition - getFirstVisiblePosition()).setVisibility(View.VISIBLE);//之前的item显示出来
            
            if(onChanageListener != null){
                onChanageListener.onChange(mDragPosition, tempPosition);
            }
            
            mDragPosition = tempPosition;
        }
    }

停止拖拽我们将之前隐藏的item显示出来，并将镜像移除

private void onStopDrag(){
        getChildAt(mDragPosition - getFirstVisiblePosition()).setVisibility(View.VISIBLE);
        removeDragImage();
    }

获取状态栏的高度

private static int getStatusHeight(Context context){
        int statusHeight = 0;
        Rect localRect = new Rect();
        ((Activity) context).getWindow().getDecorView().getWindowVisibleDisplayFrame(localRect);
        statusHeight = localRect.top;
        if (0 == statusHeight){
            Class<?> localClass;
            try {
                localClass = Class.forName("com.android.internal.R$dimen");
                Object localObject = localClass.newInstance();
                int i5 = Integer.parseInt(localClass.getField("status_bar_height").get(localObject).toString());
                statusHeight = context.getResources().getDimensionPixelSize(i5);
            } catch (Exception e) {
                e.printStackTrace();
            } 
        }
        return statusHeight;
    }

    public interface OnChanageListener{
        
        /**
         * 当item交换位置的时候回调的方法，我们只需要在该方法中实现数据的交换即可
         * @param form
         *             开始的position
         * @param to 
         *             拖拽到的position
         */
        public void onChange(int form, int to);
    }

设置响应拖拽的毫秒数和回调接口

public void setOnChangeListener(OnChanageListener onChanageListener){
        this.onChanageListener = onChanageListener;
    }
    
    public void setDragResponseMS(long dragResponseMS) {
        this.dragResponseMS = dragResponseMS;
    }

加上震动权限

<!--控制振动-->
    <uses-permission android:name="android.permission.VIBRATE"/>

使用方法

<{你的包名}.DragGridView
        android:id="@+id/dragGridView"
        android:listSelector="@android:color/transparent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:cacheColorHint="@android:color/transparent"
        android:verticalSpacing="10dip"
        android:horizontalSpacing="10dip"
        android:stretchMode="columnWidth"  
        ndroid:gravity="center" 
        android:numColumns="3" />

位置的标记

private List<HashMap<String, Object>> dataSourceList = new ArrayList<HashMap<String, Object>>();

初始化

DragGridView mDragGridView = (DragGridView) findViewById(R.id.dragGridView);

设置数据

for (int i = 0; i < 30; i++) {
            HashMap<String, Object> itemHashMap = new HashMap<String, Object>();
            itemHashMap.put("item_image",R.drawable.com_tencent_open_notice_msg_icon_big);
            itemHashMap.put("item_text", "拖拽 " + Integer.toString(i));
            dataSourceList.add(itemHashMap);
        }

拖动监听 Collections处理拖动的数据

final SimpleAdapter mSimpleAdapter = new SimpleAdapter(this, dataSourceList,
                R.layout.grid_item, new String[] { "item_image", "item_text" },
                new int[] { R.id.item_image, R.id.item_text });
        
        mDragGridView.setAdapter(mSimpleAdapter);
        
        mDragGridView.setOnChangeListener(new OnChanageListener() {
            
            @Override
            public void onChange(int from, int to) {
                HashMap<String, Object> temp = dataSourceList.get(from);
                //直接交互item
//                dataSourceList.set(from, dataSourceList.get(to));
//                dataSourceList.set(to, temp);
                
                
                //这里的处理需要注意下
                if(from < to){
                    for(int i=from; i<to; i++){
                        Collections.swap(dataSourceList, i, i+1);
                    }
                }else if(from > to){
                    for(int i=from; i>to; i--){
                        Collections.swap(dataSourceList, i, i-1);
                    }
                }
                
                dataSourceList.set(to, temp);
                
                mSimpleAdapter.notifyDataSetChanged();
                
                
            }
        });

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