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;
}
});本文到这就结束了，有需要的同学拿到轮子就可以直接使用了，谢谢！
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，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对得得之家网站的支持！
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