一个可以拖动的自定义Gridview代码

public class DragGridView extends GridView {

private long dragResponseMS = 700; // item长按响应的时间
private int mDragPosition;// 正在拖拽的position

private boolean isDrag = false; // 是否可以拖拽，用于控件内部逻辑实现
private boolean canDrag = true; // 是否可用拖拽，主要用于外部开放设置
private boolean mAnimationEnd = true;

private int mDownX;
private int mDownY;
private int moveX;
private int moveY;

private View mStartDragItemView = null; // 刚开始拖拽的item对应的View
private ImageView mDragImageView; // 用于拖拽时显示的幻影镜像
private Bitmap mDragBitmap; // 幻影镜像对应的Bitmap

private final Vibrator mVibrator; // 震动器
private final int mStatusHeight;// 状态栏的高度
private final WindowManager mWindowManager;
private WindowManager.LayoutParams mWindowLayoutParams; // item镜像的布局参数

private int mPoint2ItemTop; // 按下的点到所在item的上边缘的距离
private int mPoint2ItemLeft;
private int mOffset2Top; // DragGridView距离屏幕顶部的偏移量
private int mOffset2Left;

private int mDownScrollBorder; // DragGridView自动向下滚动的边界值
private int mUpScrollBorder; // DragGridView自动向上滚动的边界值

private DragGridBaseAdapter mDragAdapter;
private int mNumColumns;
private int mColumnWidth;
private boolean mNumColumnsSet;
private int mHorizontalSpacing;

private static final int speed = 20; // DragGridView自动滚动的速度
private static final int MOVE_OFFSET = 25;
private boolean moved = false;

public static final int HANDLE_START = 0x3587;
public static final int HANDLE_CANCLE = 0x3588;
public static final int HANDLE_FINISH = 0x3589;
private static OnMoveListener moveListener; // 拖拽开始与结束监听器
private OnDeleteListener deleteListener; // 移动到垃圾桶时的监听器

private float dragViewScale = 1.3f;

private final TouchRect moveRect = new TouchRect();
private final TouchRect gridRect = new TouchRect();
private final TouchRect trashRect = new TouchRect();

public DragGridView(Context context) {
this(context, null);
}

public DragGridView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public DragGridView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mVibrator = (Vibrator) context
.getSystemService(Context.VIBRATOR_SERVICE);
mWindowManager = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
mStatusHeight = getStatusHeight(context); // 获取状态栏的高度

if (!mNumColumnsSet) {
mNumColumns = AUTO_FIT;
}
}

/**
* 获取状态栏的高度
*
* @param context
* @return
*/
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;
}

private static final Handler mHandler = new Handler() {
@Override
public void handleMessage(android.os.Message msg) {
if (moveListener != null) {
if (msg.what == HANDLE_START) {
moveListener.startMove();
} else if (msg.what == HANDLE_FINISH) {
moveListener.finishMove();
} else if (msg.what == HANDLE_CANCLE) {
moveListener.cancleMove();
}
}
}

;
};

// 用来处理是否为长按的Runnable
private final Runnable mLongClickRunnable = new Runnable() {
@Override
public void run() {
if (!canDrag) {
return;
}
isDrag = true; // 设置可以拖拽
moved = true;
mHandler.sendEmptyMessage(HANDLE_START);
mVibrator.vibrate(50); // 震动一下

mStartDragItemView.setVisibility(View.INVISIBLE);// 隐藏该item

createDragImage(mDragBitmap, mDownX, mDownY);
mDragBitmap = null;
}
};

/**
* 若设置为AUTO_FIT，计算有多少列
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (mNumColumns == AUTO_FIT) {
int numFittedColumns = 1; // 可用列

if (mColumnWidth > 0) {
int gridWidth = Math.max(MeasureSpec.getSize(widthMeasureSpec)
- getPaddingLeft() - getPaddingRight(), 0);
numFittedColumns = gridWidth / mColumnWidth;
if (numFittedColumns > 0) {
while (numFittedColumns != 1) {
if (numFittedColumns * mColumnWidth
+ (numFittedColumns - 1) * mHorizontalSpacing > gridWidth) {
numFittedColumns--;
} else {
break;
}
}
}
} else {
numFittedColumns = 2;
}
mNumColumns = numFittedColumns;
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
initRecord();
}

/**
* 初始化坐标数据
*/
private void initRecord() {
gridRect.left = this.getLeft();
gridRect.right = this.getRight();
gridRect.top = this.getTop();
gridRect.bottom = this.getBottom();
}

@Override
public void setAdapter(ListAdapter adapter) {
super.setAdapter(adapter);

if (adapter instanceof DragGridBaseAdapter) {
mDragAdapter = (DragGridBaseAdapter) adapter;
} else {
throw new IllegalStateException(
"the adapter must be implements DragGridAdapter");
}
}

@Override
public void setNumColumns(int numColumns) {
super.setNumColumns(numColumns);
mNumColumnsSet = true;
this.mNumColumns = numColumns;
}

@Override
public void setColumnWidth(int columnWidth) {
super.setColumnWidth(columnWidth);
mColumnWidth = columnWidth;
}

@Override
public void setHorizontalSpacing(int horizontalSpacing) {
super.setHorizontalSpacing(horizontalSpacing);
this.mHorizontalSpacing = horizontalSpacing;
}

/**
* 设置响应拖拽的毫秒数，默认是700毫秒
* @param dragResponseMS
*/
public void setDragResponseMS(long dragResponseMS) {
this.dragResponseMS = dragResponseMS;
}

public void setOnDeleteListener(OnDeleteListener l) {
this.deleteListener = l;
}

public void setDragEnable(boolean isDrag) {
this.canDrag = isDrag;
if (canDrag) {
mHandler.removeCallbacks(mLongClickRunnable);
}
}

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
if (canDrag) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mDownX = (int) ev.getX();
mDownY = (int) ev.getY();
moveRect.left = mDownX - MOVE_OFFSET;
moveRect.right = mDownX + MOVE_OFFSET;
moveRect.top = mDownY - MOVE_OFFSET;
moveRect.bottom = mDownY + MOVE_OFFSET;

// 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 || mDragPosition == getDragAdapter().getRealCount()) {
return super.dispatchTouchEvent(ev);
}

// 使用Handler延迟dragResponseMS执行mLongClickRunnable
mHandler.postDelayed(mLongClickRunnable, dragResponseMS);

// 根据position获取该item所对应的View
mStartDragItemView = getChildAt(mDragPosition
- getFirstVisiblePosition());

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() / 5;
// 大于这个值，DragGridView向上滚动
mUpScrollBorder = getHeight() * 4 / 5;

// 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:
// 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(moveRect, ev.getX(), ev.getY())) {
mHandler.removeCallbacks(mLongClickRunnable);
}
break;
case MotionEvent.ACTION_UP:
mHandler.removeCallbacks(mScrollRunnable);
mHandler.removeCallbacks(mLongClickRunnable);
if (moved && getAdapter().getCount() > 0) {
mHandler.sendEmptyMessage(HANDLE_FINISH);
} else {
mHandler.sendEmptyMessage(HANDLE_CANCLE);
}
moved = false;
break;
}
}
return super.dispatchTouchEvent(ev);
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
if (isDrag && canDrag && mDragImageView != null) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
initRecord();
break;
case MotionEvent.ACTION_MOVE:
moveX = (int) ev.getX();
moveY = (int) ev.getY();

onDragItem(moveX, moveY);// 拖动item
break;
case MotionEvent.ACTION_UP:
onStopDrag();
isDrag = false;
break;
}
return true;
}
return super.onTouchEvent(ev);
}

/**
* 是否点击在GridView的item上面
*
* @param moveRect
* @param x
* @param y
* @return
*/
private boolean isTouchInItem(TouchRect moveRect, float x, float y) {
// 防止手抖的处理，如果是横向在item上移动是没有影响的，
// 但是纵向由于外层上下拉控件还是会有影响，具体解决请看NoteBookFragment类中的mSwipeRefreshLayout.setOnTouchListener方法
if (x < moveRect.right && x > moveRect.left && y < moveRect.bottom
&& y > moveRect.top) {
return true;
} else {
return false;
}
}

/**
* 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;
initDragOffset(bitmap);
mWindowLayoutParams.x = downX - mPoint2ItemLeft + mOffset2Left;
mWindowLayoutParams.y = downY - mPoint2ItemTop + mOffset2Top - mStatusHeight;
mWindowLayoutParams.alpha = 0.618f; // 透明度
mWindowLayoutParams.width = (int) (bitmap.getWidth() * dragViewScale);
mWindowLayoutParams.height = (int) (bitmap.getHeight() * dragViewScale);
mWindowLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;

mDragImageView = new ImageView(getContext());
mDragImageView.setScaleType(ImageView.ScaleType.FIT_XY);
mDragImageView.setImageBitmap(bitmap);
mWindowManager.addView(mDragImageView, mWindowLayoutParams);
}

private void initDragOffset(Bitmap bitmap){
mOffset2Left = mOffset2Left - (int) (bitmap.getWidth() * (dragViewScale - 1) / 2);
mOffset2Top = mOffset2Top - (int) (bitmap.getHeight() * (dragViewScale - 1) / 2);
}

/**
* 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 moveX
* @param moveY
*/
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，触发GridView自动向下滚动
* 否则不进行滚动
*/
private final Runnable mScrollRunnable = new Runnable() {

@Override
public void run() {
int scrollY;
if (getFirstVisiblePosition() == 0
|| getLastVisiblePosition() == getCount() - 1) {
mHandler.removeCallbacks(mScrollRunnable);
}

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);
}

smoothScrollBy(scrollY, 10);
}
};

/**
* 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

final 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
&& tempPosition != getDragAdapter().getRealCount()
&& mAnimationEnd) {
mDragAdapter.reorderItems(mDragPosition, tempPosition);
mDragAdapter.setHideItem(tempPosition);

final ViewTreeObserver observer = getViewTreeObserver();
observer.addOnPreDrawListener(new OnPreDrawListener() {

@Override
public boolean onPreDraw() {
observer.removeOnPreDrawListener(this);
animateReorder(mDragPosition, tempPosition);
mDragPosition = tempPosition;
return true;
}
});

}
}

/**
* 创建移动动画
*
* @param view
* @param startX
* @param endX
* @param startY
* @param endY
* @return
*/
private AnimatorSet createTranslationAnimations(View view, float startX,
float endX, float startY, float endY) {
ObjectAnimator animX = ObjectAnimator.ofFloat(view, "translationX",
startX, endX);
ObjectAnimator animY = ObjectAnimator.ofFloat(view, "translationY",
startY, endY);
AnimatorSet animSetXY = new AnimatorSet();
animSetXY.playTogether(animX, animY);
return animSetXY;
}

/**
* item的交换动画效果
*
* @param oldPosition
* @param newPosition
*/
private void animateReorder(final int oldPosition, final int newPosition) {
boolean isForward = newPosition > oldPosition;
List<Animator> resultList = new LinkedList<Animator>();
if (isForward) {
for (int pos = oldPosition; pos < newPosition; pos++) {
View view = getChildAt(pos - getFirstVisiblePosition());
if (view == null) {
continue;
}
if ((pos + 1) % mNumColumns == 0) {
resultList.add(createTranslationAnimations(view,
-view.getWidth() * (mNumColumns - 1), 0,
view.getHeight(), 0));
} else {
resultList.add(createTranslationAnimations(view,
view.getWidth(), 0, 0, 0));
}
}
} else {
for (int pos = oldPosition; pos > newPosition; pos--) {
View view = getChildAt(pos - getFirstVisiblePosition());
if ((pos + mNumColumns) % mNumColumns == 0) {
resultList.add(createTranslationAnimations(view,
view.getWidth() * (mNumColumns - 1), 0,
-view.getHeight(), 0));
} else {
resultList.add(createTranslationAnimations(view,
-view.getWidth(), 0, 0, 0));
}
}
}

AnimatorSet resultSet = new AnimatorSet();
resultSet.playTogether(resultList);
resultSet.setDuration(300);
resultSet.setInterpolator(new AccelerateDecelerateInterpolator());
resultSet.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationStart(Animator animation) {
mAnimationEnd = false;
}

@Override
public void onAnimationEnd(Animator animation) {
mAnimationEnd = true;
}
});
resultSet.start();
}

/**
* 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() {
View view = getChildAt(mDragPosition - getFirstVisiblePosition());
if (view != null) {
view.setVisibility(View.VISIBLE);
}
mDragAdapter.setHideItem(-1);
removeDragImage();
}

private DragGridBaseAdapter getDragAdapter() {
return (DragGridBaseAdapter) getAdapter();
}

public void setOnMoveListener(OnMoveListener listener) {
moveListener = listener;
}

public interface OnMoveListener {
void startMove();

void finishMove();

void cancleMove();
}

public interface OnDeleteListener {
void onDelete(int position);
}

public interface DragGridBaseAdapter {
/**
* 移动时回调
*/
void reorderItems(int oldPosition, int newPosition);

/**
* 隐藏时回调
*/
void setHideItem(int hidePosition);

int getRealCount();
}

private class TouchRect {
int top;
int bottom;
int left;
int right;
}
}