可拖拽的GridView

来源：互联网发布：数据科学北大编辑：程序博客网时间：2024/05/22 00:12

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.TranslateAnimation;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.ImageView;

import com.ebensz.enote.notepad.R;
import com.ebensz.enote.notepad.browser.BrowserController;
import com.ebensz.enote.notepad.ui.adapter.BrowserGridAdapter;

public class DraggableGridView extends GridView {

   private static final int DRAG_MODE_DELAY = 500;
   private static final int DRAG_MODE_MSG = 10001;

    private static final int UP_SCROLL_BOUNCE = 150;// 拖动的时候，开始向上滚动的边界
    private static final int DOWN_SCROLL_BOUNCE = 850;// 拖动的时候，开始向下滚动的边界

   public DraggableGridView(Context context, AttributeSet attrs) {
       super(context, attrs);
       columns = context.getResources().getInteger(R.integer.grid_columns);
   }

   public void setBrowserController(BrowserController browserController) {
       this.browserController = browserController;
   }

   public boolean isDataChanged() {
       return isDataChanged;
   }

   public void cancelDrag() {
       isDataChanged = false;
       isDragMode = false;
   }

   public int getDropPosition() {
       return dropPosition;
   }

   public int getColumns() {
       return columns;
   }

   public void sendMsgDelayed() {
       handler.removeMessages(DRAG_MODE_MSG);
       if (!browserController.isStartDragEnable() || startPosition == AdapterView.INVALID_POSITION || getAdapter().getCount() < 2) {
           return;
       }

       handler.sendEmptyMessageDelayed(DRAG_MODE_MSG, DRAG_MODE_DELAY);
   }

   public View getChildViewAt(int index) {
       int position = getVisibleItemIndex(index);

       if (position < 0 || position > (getCount() - 1)) {
           return null;
       }

       return getChildAt(position);
   }

   @Override
   public boolean onHoverEvent(MotionEvent event) {
       handler.removeMessages(DRAG_MODE_MSG);

       if (isDragMode) {
           isDragMode = false;
           onDrop();
       }

       return super.onHoverEvent(event);
   }

   @Override
   public boolean onTouchEvent(MotionEvent ev) {

       int x = (int) ev.getX();
       int y = (int) ev.getY();
       final int rawY = (int) ev.getRawY();
       final int action = ev.getActionMasked();

       switch (action) {
       case MotionEvent.ACTION_DOWN:
           init(ev);
           if (null == itemView) {
               return super.onTouchEvent(ev);
           }

           if (isDragMode) {
               prepareDrag(itemView);
           }

           break;

       case MotionEvent.ACTION_MOVE:
           if (isDragMode) {
               onDrag(x, y, rawY);

               if (!isMoving && (rawY > UP_SCROLL_BOUNCE && rawY < DOWN_SCROLL_BOUNCE)) {
                   onMove(x, y);
               }
           }

           break;

       case MotionEvent.ACTION_UP:
           handler.removeMessages(DRAG_MODE_MSG);

           if (!isDataChanged && null != itemView) {
               itemView.setVisibility(View.VISIBLE);
           }

           if (isDragMode) {
               onDrop();
           }

           isDragMode = false;

           break;
       }

       return super.onTouchEvent(ev);
   }

   private void prepareDrag(View itemView) {
       itemView.destroyDrawingCache();
       itemView.setDrawingCacheEnabled(true);
       itemView.setDrawingCacheBackgroundColor(0x000000);

       Bitmap drawingCache = Bitmap.createBitmap(itemView
               .getDrawingCache(true));

       Bitmap substitute = Bitmap.createBitmap(drawingCache, 0, 0,
               drawingCache.getWidth(),
               drawingCache.getHeight());

       startDrag(substitute, downX, downY);

       setDropItemVisible(false);

       itemView.setVisibility(View.INVISIBLE);
   }

   private Handler handler = new Handler(){
       @Override
       public void handleMessage(Message msg) {
           if (msg.what == DRAG_MODE_MSG) {
               isDragMode = true;
               prepareDrag(itemView);
           }
       }
   };

   private void init(MotionEvent ev){
       downX = (int) ev.getX();
        downY = (int) ev.getY();

        startPosition = dragPosition = dropPosition = pointToPosition(downX, downY);

        if (dragPosition == AdapterView.INVALID_POSITION) {
           itemView = null;
           return;
       }

        itemView = getChildAt(dragPosition - getFirstVisiblePosition());

        // 得到当前点在item内部的偏移量即相对于item左上角的坐标
       dragPointX = downX - itemView.getLeft();
       dragPointY = downY - itemView.getTop();

       dragOffsetX = (int) (ev.getRawX() - downX);
       dragOffsetY = (int) (ev.getRawY() - downY);

       isMoving = false;
   }

   private void startDrag(Bitmap bm, int x, int y) {
       stopDrag();

       windowParams = new WindowManager.LayoutParams();

       windowParams.gravity = Gravity.TOP | Gravity.LEFT;// 这个必须加
       // 得到preview左上角相对于屏幕的坐标
       windowParams.x = x - dragPointX + dragOffsetX - 10;
       windowParams.y = y - dragPointY + dragOffsetY - 10;
       // 设置宽和高
       windowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
       windowParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
       windowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
               | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
               | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
               | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;

       windowParams.format = PixelFormat.TRANSLUCENT;
       windowParams.windowAnimations = 0;

       ImageView iv = new ImageView(getContext());
       iv.setImageBitmap(bm);
       windowManager = (WindowManager) getContext().getSystemService(
               Context.WINDOW_SERVICE);// "window"
       windowManager.addView(iv, windowParams);
       dragImageView = iv;
   }

   private void enterDragMode() {
       browserController.exitSelectMode(false);
       browserController.enterDragMode();
   }

    private void onMove(int x, int y) {
        final int position = pointToPosition(x, y);

       if (position != AdapterView.INVALID_POSITION && position != dragPosition) {
           dropPosition = position;
       }

       dragPosition = startPosition;

        int moveNum = dropPosition - dragPosition;
        if (moveNum != 0) {

           enterDragMode();

            int moveNumAbs = Math.abs(moveNum);
            float offsetX, offsetY;

            for (int i = 0; i < moveNumAbs; i++) {

                int holdPosition;

                if (moveNum > 0) {
                    holdPosition = dragPosition + 1;
                    offsetX = (dragPosition / columns == holdPosition / columns) ? (-1) : (columns - 1);
                    offsetY = (dragPosition / columns == holdPosition / columns) ? 0 : (-1);
                }
                else {
                    holdPosition = dragPosition - 1;
                    offsetX = (dragPosition / columns == holdPosition / columns) ? 1 : (-(columns - 1));
                    offsetY = (dragPosition / columns == holdPosition / columns) ? 0 : 1;
                }

                final ViewGroup moveView = (ViewGroup) getChildViewAt(holdPosition);
                Animation animation = getMoveAnimation(offsetX, offsetY);
                moveView.startAnimation(animation);

                dragPosition = holdPosition;

                if (dragPosition == dropPosition) {
                    lastAnimationID = animation.toString();
                }

                final BrowserGridAdapter adapter = (BrowserGridAdapter)getAdapter();
                animation.setAnimationListener(new AnimationListener() {

                   @Override
                   public void onAnimationStart(Animation animation) {
                       isMoving = true;
                   }

                   @Override
                   public void onAnimationRepeat(Animation animation) {
                   }

                   @Override
                   public void onAnimationEnd(Animation animation) {
                       isMoved = true;
                       isDataChanged = true;
                        String animationId = animation.toString();

                        if (animationId.equalsIgnoreCase(lastAnimationID)) {
                            adapter.exchangePages(startPosition, dropPosition);
                            startPosition = dropPosition;
                            isMoving = false;
                        }

                        moveView.clearAnimation();
                   }
               });
            }
        }
    }

   private int getVisibleItemIndex(int dragPosition) {
       int firstVisiblePosition = getFirstVisiblePosition();

       int index = Math.abs(dragPosition - firstVisiblePosition);
       int visibleCount = getLastVisiblePosition() - firstVisiblePosition;
       if (index > visibleCount) {
           index = visibleCount - 1;
       }

       return index;
   }

    private void onDrop() {
       stopDrag();

        final BrowserGridAdapter adapter = (BrowserGridAdapter) this.getAdapter();
        adapter.showDropItem(true);
        adapter.notifyDataSetChanged();

        if (isMoved) {
           browserController.setSelectedPosition(dropPosition);
           adapter.draggedChangeData(dropPosition);
           isMoved = false;
       }
    }

   private void onDrag(int x, int y,int rawY) {

       if (dragImageView != null) {
           windowParams.alpha = 0.6f;
           windowParams.x = x - dragPointX + dragOffsetX;
           windowParams.y = y - dragPointY + dragOffsetY;
           windowManager.updateViewLayout(dragImageView, windowParams);
       }

        // 滚动
        int scrollHeight = 0;
        if (rawY < UP_SCROLL_BOUNCE) {
           scrollHeight = -150;
        }
        else if (rawY > DOWN_SCROLL_BOUNCE) {
            scrollHeight = 150;
        }

        if (scrollHeight != 0) {
           smoothScrollBy(scrollHeight,0);
        }
   }

   private void stopDrag() {
       if (dragImageView != null) {
           windowManager.removeView(dragImageView);
           dragImageView = null;
       }
   }

    private Animation getMoveAnimation(float x, float y) {

        TranslateAnimation go = new TranslateAnimation(
                Animation.RELATIVE_TO_SELF,
                0,
                Animation.RELATIVE_TO_SELF,
                x,
                Animation.RELATIVE_TO_SELF,
                0,
                Animation.RELATIVE_TO_SELF,
                y
        );

        go.setFillAfter(true);
        go.setDuration(150);

        return go;
    }

    private void setDropItemVisible(boolean isVisible) {
        final BrowserGridAdapter adapter = (BrowserGridAdapter) this.getAdapter();
        adapter.showDropItem(isVisible);
    }

    private BrowserController browserController;

    private View itemView;

    private boolean isDataChanged;
    private boolean isDragMode;

   private int columns;
   private int dragPosition;// 开始拖拽的位置
   private int dropPosition;// 结束拖拽的位置
   private int dragPointX; // 相对于item的x坐标
   private int dragPointY; // 相对于item的y坐标
   private int dragOffsetX;
   private int dragOffsetY;
   private ImageView dragImageView; // 拖动item的preview

   private WindowManager windowManager;
   private WindowManager.LayoutParams windowParams;

   private int startPosition;
   private int downX,downY;
    private String lastAnimationID;

    private boolean isMoved;
    private boolean isMoving;
}