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Android自定義gridView仿頭條頻道拖動管理功能

來源：本站原創(chuàng)|時間：2020-01-10|欄目：Android|點(diǎn)擊： 次

項(xiàng)目中遇到這樣個需求：app的功能導(dǎo)航需要可拖動排序，類似頭條中的頻道拖動管理。效果如下，gif不是很順暢，真機(jī)會好很多。

雖然類似的文章網(wǎng)上搜一下有很多，但寫的都不令人滿意，注釋不清晰，而且動畫還不夠流暢。經(jīng)本人整理優(yōu)化后，拿出來供后續(xù)有需要的使用。

實(shí)現(xiàn)原理：

  • gridView作為基本控件
  • WindowManager.addView的方式實(shí)現(xiàn)可拖動的view
  • TranslateAnimation實(shí)現(xiàn)移動動畫，動畫完后更新adapter即可

主要的實(shí)現(xiàn)原理上面已經(jīng)說明，源碼中關(guān)鍵的地點(diǎn)也有注釋，因此下面直接上源碼。

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;
/**
 * 長按拖動圖標(biāo)可以調(diào)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;//拖動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();// 算出行數(shù)
    int left = (itemCount % getNumColumns());// 算出最后一行多余的數(shù)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左上角相對于屏幕的坐標(biāo)
  windowParams.x = rawX - viewL;
  windowParams.y = rawY - viewT;
  //設(shè)置拖拽item的寬和高
  windowParams.width = (int) (dragScale * dragBitmap.getWidth());// 放大dragScale倍，可以設(shè)置拖動后的倍數(shù)
  windowParams.height = (int) (dragScale * dragBitmap.getHeight());// 放大dragScale倍，可以設(shè)置拖動后的倍數(shù)
  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);//動畫還未執(zhí)行完的情況下，重設(shè)動畫會清除之前設(shè)置的動畫。
     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) {
    //移動位置在還未到新item內(nèi)
    return;
   }
   //移需要移動的動ITEM數(shù)量
   int moveCount = targetPosition - lastPosition;
   if (moveCount != 0) {
    if (isMoveUp) {//手指抬起時，不執(zhí)行動畫直接交換數(shù)據(jù)
     Adapter adapter = (Adapter) getAdapter();
     adapter.exchange(lastPosition, targetPosition);
     lastPosition = targetPosition;
     isMoving = false;
    } else {
     int moveCountAbs = Math.abs(moveCount);
     float toXvalue = 0, toYvalue = 0;
     //moveXP移動的距離百分比（相對于自己長度的百分比）
     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++) {
      //從左往右，或是從上往下
      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 {
       //從右往左，或是從下往上
       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) {
        // 如果為最后個動畫結(jié)束，那執(zhí)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);// 設(shè)置一個動畫效果執(zhí)行完畢后，View對象保留在終止的位置。
  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;
  }
 }
}

主要的代碼就是DragGridView，拿到此view實(shí)現(xiàn)起來就相當(dāng)簡單了。為了文章完整性，下面也貼上本效果圖的主要使用代碼。

String[] items = new String[]{"頭條", "視頻", "娛樂", "體育", "北京", "新時代"
      , "網(wǎng)易號", "段子", "冰雪運(yùn)動", "科技", "汽車", "輕松一刻"
      , "時尚", "直播", "圖片", "跟帖", "NBA", "態(tài)度公開課"
      , "推薦", "熱點(diǎn)", "社會", "趣圖", "美女", "軍事"};
      
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();
      }
  ...省略部分代碼
      @Override
      public View getView(int position, View convertView, ViewGroup parent) {
        //todo,這里需要優(yōu)化，沒有復(fù)用views。也不能按傳統(tǒng)方式服用view，否則會造成拖動的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;
      }
    });

本文到這就結(jié)束了，有需要的同學(xué)拿到輪子就可以直接使用了，謝謝！

不知道有沒有眼尖的同學(xué)發(fā)現(xiàn)Adapterd的getView方法中有個 todo需要優(yōu)化。原因是這樣：如果打開注釋中的代碼，復(fù)用convertView，會造成gridView釋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個convertView。
希

總結(jié)

以上所述是小編給大家介紹的Android自定義gridView仿頭條頻道拖動管理功能，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復(fù)大家的。在此也非常感謝大家對我們網(wǎng)站的支持！
如果你覺得本文對你有幫助，歡迎轉(zhuǎn)載，煩請注明出處，謝謝！

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