Android如何自定义gridView仿头条频道拖动管理功能

这篇文章主要介绍Android如何自定义gridView仿头条频道拖动管理功能，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！

项目中遇到这样个需求：app的功能导航需要可拖动排序，类似头条中的频道拖动管理。效果如下，gif不是很顺畅，真机会好很多。

虽然类似的文章网上搜一下有很多，但写的都不令人满意，注释不清晰，而且动画还不够流畅。经本人整理优化后，拿出来供后续有需要的使用。

实现原理：

gridView作为基本控件  WindowManager.addView的方式实现可拖动的view  TranslateAnimation实现移动动画，动画完后更新adapter即可

主要的实现原理上面已经说明，源码中关键的地点也有注释，因此下面直接上源码。

package com.hai.draggrid;import android.content.Context;import android.graphics.Bitmap;import android.graphics.PixelFormat;import android.util.AttributeSet;import android.view.Gravity;import android.view.MotionEvent;import android.view.View;import android.view.WindowManager;import android.view.animation.Animation;import android.view.animation.TranslateAnimation;import android.widget.AdapterView;import android.widget.BaseAdapter;import android.widget.GridView;import android.widget.ImageView;/** * 长按拖动图标可以调整item位置的Gridview * Created by huanghp on 2019/10/15. * Email h2132760021@sina.com */public class DragGridView extends GridView { private static final String TAG = "DragGridView"; private int downX, downY; private int rawX, rawY; private int lastPosition = INVALID_POSITION; private int viewL, viewT; private int itemHeight, itemWidth; private int itemCount; private double dragScale = 1.2D;//拖动view的放大比例 private ImageView dragImageView; private WindowManager windowManager = null; private WindowManager.LayoutParams windowParams = null; private boolean isMoving = false; private Animation lastAnimation; private static final long TIME_ANIMATE = 300; public DragGridView(Context context, AttributeSet attrs) {  this(context, attrs, 0); } public DragGridView(Context context, AttributeSet attrs, int defStyleAttr) {  super(context, attrs, defStyleAttr);  setOnItemLongClickListener(new OnItemLongClickListener() {   @Override   public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {    lastPosition = position;    View dragView = getChildAt(lastPosition - getFirstVisiblePosition());    itemHeight = dragView.getHeight();    itemWidth = dragView.getWidth();    itemCount = getCount();    int rows = itemCount / getNumColumns();// 算出行数    int left = (itemCount % getNumColumns());// 算出最后一行多余的数量    if (lastPosition != INVALID_POSITION) {     viewL = downX - dragView.getLeft();     viewT = downY - dragView.getTop();     dragView.destroyDrawingCache();     dragView.setDrawingCacheEnabled(true);     Bitmap bitmap = Bitmap.createBitmap(dragView.getDrawingCache());     startDrag(bitmap);     dragView.setVisibility(INVISIBLE);     isMoving = false;     ((Adapter) getAdapter()).setIsDrag(true);     requestDisallowInterceptTouchEvent(true);     return true;    }    return false;   }  }); } private void startDrag(Bitmap dragBitmap) {  stopDrag();  windowParams = new WindowManager.LayoutParams();  windowParams.gravity = Gravity.TOP | Gravity.LEFT;  //得到preview左上角相对于屏幕的坐标  windowParams.x = rawX - viewL;  windowParams.y = rawY - viewT;  //设置拖拽item的宽和高  windowParams.width = (int) (dragScale * dragBitmap.getWidth());// 放大dragScale倍，可以设置拖动后的倍数  windowParams.height = (int) (dragScale * dragBitmap.getHeight());// 放大dragScale倍，可以设置拖动后的倍数  this.windowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE    | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE    | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON    | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;  this.windowParams.format = PixelFormat.TRANSLUCENT;  this.windowParams.windowAnimations = 0;  ImageView iv = new ImageView(getContext());  iv.setImageBitmap(dragBitmap);  windowManager = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);  windowManager.addView(iv, windowParams);  dragImageView = iv; } private void stopDrag() {  if (dragImageView != null && windowManager != null) {   windowManager.removeView(dragImageView);   dragImageView = null;  } } @Override public boolean onTouchEvent(MotionEvent ev) {  int x = (int) ev.getX();  int y = (int) ev.getY();  switch (ev.getAction()) {   case MotionEvent.ACTION_DOWN:    downX = x;    downY = y;    rawX = (int) ev.getRawX();    rawY = (int) ev.getRawY();    break;   case MotionEvent.ACTION_MOVE:    if (dragImageView != null && lastPosition != INVALID_POSITION) {     updateDrag((int) ev.getRawX(), (int) ev.getRawY());     if (!isMoving) onMove(x, y, false);    }    break;   case MotionEvent.ACTION_UP://    Log.e(TAG, "dragImageView is null=" + (dragImageView == null) + ",lastposition=" + lastPosition//      + ",pointToPosition=" + pointToPosition(x, y) + ",ismove=" + isMoving);    if (dragImageView != null && lastPosition != INVALID_POSITION) {//     if (isMoving) onMove(x, y, true);//动画还未执行完的情况下，重设动画会清除之前设置的动画。     stopDrag();     ((Adapter) getAdapter()).setIsDrag(false);     ((BaseAdapter) getAdapter()).notifyDataSetChanged();     requestDisallowInterceptTouchEvent(false);    }    break;  }  return super.onTouchEvent(ev); } private void onMove(int moveX, int moveY, boolean isMoveUp) {  final int targetPosition = pointToPosition(moveX, moveY);  if (targetPosition != INVALID_POSITION) {   if (targetPosition == lastPosition) {    //移动位置在还未到新item内    return;   }   //移需要移动的动ITEM数量   int moveCount = targetPosition - lastPosition;   if (moveCount != 0) {    if (isMoveUp) {//手指抬起时，不执行动画直接交换数据     Adapter adapter = (Adapter) getAdapter();     adapter.exchange(lastPosition, targetPosition);     lastPosition = targetPosition;     isMoving = false;    } else {     int moveCountAbs = Math.abs(moveCount);     float toXvalue = 0, toYvalue = 0;     //moveXP移动的距离百分比（相对于自己长度的百分比）     float moveXP = ((float) getHorizontalSpacing() / (float) itemWidth) + 1.0f;     float moveYP = ((float) getVerticalSpacing() / (float) itemHeight) + 1.0f;     int holdPosition;//     Log.d(TAG, "start annimation=" + moveCountAbs);     for (int i = 0; i < moveCountAbs; i++) {      //从左往右，或是从上往下      if (moveCount > 0) {       holdPosition = lastPosition + i + 1;       //同一行       if (lastPosition / getNumColumns() == holdPosition / getNumColumns()) {        toXvalue = -moveXP;        toYvalue = 0;       } else if (holdPosition % getNumColumns() == 0) {        toXvalue = (getNumColumns() - 1) * moveXP;        toYvalue = -moveYP;       } else {        toXvalue = -moveXP;        toYvalue = 0;       }      } else {       //从右往左，或是从下往上       holdPosition = lastPosition - i - 1;       if (lastPosition / getNumColumns() == holdPosition / getNumColumns()) {        toXvalue = moveXP;        toYvalue = 0;       } else if ((holdPosition + 1) % getNumColumns() == 0) {        toXvalue = -(getNumColumns() - 1) * moveXP;        toYvalue = moveYP;       } else {        toXvalue = moveXP;        toYvalue = 0;       }      }      View holdView = getChildAt(holdPosition);      Animation moveAnimation = createAnimation(toXvalue, toYvalue);      moveAnimation.setAnimationListener(new Animation.AnimationListener() {       @Override       public void onAnimationStart(Animation animation) {        isMoving = true;       }       @Override       public void onAnimationRepeat(Animation animation) {       }       @Override       public void onAnimationEnd(Animation animation) {        // 如果为最后个动画结束，那执行下面的方法        if (animation == lastAnimation) {         Adapter adapter = (Adapter) getAdapter();         adapter.exchange(lastPosition, targetPosition);         lastPosition = targetPosition;         isMoving = false;        }       }      });      holdView.startAnimation(moveAnimation);      if (holdPosition == targetPosition) {       lastAnimation = moveAnimation;      }     }    }   }  } } public Animation createAnimation(float toXValue, float toYValue) {  TranslateAnimation mTranslateAnimation = new TranslateAnimation(    Animation.RELATIVE_TO_SELF, 0.0F, Animation.RELATIVE_TO_SELF, toXValue,    Animation.RELATIVE_TO_SELF, 0.0F, Animation.RELATIVE_TO_SELF, toYValue);  mTranslateAnimation.setFillAfter(true);// 设置一个动画效果执行完毕后，View对象保留在终止的位置。  mTranslateAnimation.setDuration(TIME_ANIMATE);  return mTranslateAnimation; } private void updateDrag(int rawX, int rawY) {  windowParams.alpha = 0.6f;  windowParams.x = rawX - viewL;  windowParams.y = rawY - viewT;  windowManager.updateViewLayout(dragImageView, windowParams); } static abstract class Adapter extends BaseAdapter {  protected boolean isDrag;  protected int holdPosition = -1;  public void setIsDrag(boolean isDrag) {   this.isDrag = isDrag;  }  public void exchange(int startPosition, int endPositon) {   holdPosition = endPositon;  } }}

主要的代码就是DragGridView，拿到此view实现起来就相当简单了。为了文章完整性，下面也贴上本效果图的主要使用代码。

String[] items = new String[]{"头条", "视频", "娱乐", "体育", "北京", "新时代"      , "网易号", "段子", "冰雪运动", "科技", "汽车", "轻松一刻"      , "时尚", "直播", "图片", "跟帖", "NBA", "态度公开课"      , "推荐", "热点", "社会", "趣图", "美女", "军事"};      gridView.setAdapter(new DragGridView.Adapter() {      @Override      public void exchange(int startPosition, int endPositon) {        super.exchange(startPosition, endPositon);        String item = list.get(startPosition);        if (startPosition < endPositon) {          list.add(endPositon + 1, item);          list.remove(startPosition);        } else {          list.add(endPositon, item);          list.remove(startPosition + 1);        }        for (int i = 0; i < list.size(); i++) {          Log.e(TAG, "exchange: =" + list.get(i));        }        notifyDataSetChanged();      }  ...省略部分代码      @Override      public View getView(int position, View convertView, ViewGroup parent) {        //todo,这里需要优化，没有复用views。也不能按传统方式服用view，否则会造成拖动的view空白//        if (convertView == null) {        convertView = getLayoutInflater().inflate(R.layout.item, parent, false);//        }        ((TextView) convertView.findViewById(R.id.tv)).setText(getItem(position));        if (isDrag && position == holdPosition) {          convertView.setVisibility(View.INVISIBLE);        } else convertView.setVisibility(View.VISIBLE);        return convertView;      }    });

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