Android自定义gridView仿头条频道拖动管理功能

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 h1132760021@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;
     }
   });

不知道有没有眼尖的同学发现Adapterd的getView方法中有个 todo需要优化。原因是这样：如果打开注释中的代码，复用convertView，会造成gridView释放后的新位置一片空白，不知道什么原因，因此折中的方法就是每次都是新生成一个convertView。
希

总结

以上所述是小编给大家介绍的Android自定义gridView仿头条频道拖动管理功能网站的支持！
如果你觉得本文对你有帮助，欢迎转载，烦请注明出处，谢谢！

来源：https://blog.csdn.net/u014763302/article/details/103682923