Android Open Source - SpeechWriter Drag N Drop List View

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License

The source code is released under:

MIT License

Java Source Code

/*
 * Copyright (C) 2010 Eric Harlow/*from   w  w  w  .jav  a2  s.co m*/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * THE ORIGINAL FILE WAS MODIFIED
 */

package com.ericharlow.DragNDrop;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.ListView;

public class DragNDropListView extends ListView {

  boolean mDragMode;

  int mStartPosition;
  int mEndPosition;
  int mDragPointOffset;    //Used to adjust drag view location
  
  //Used to recognize a click.
  private final float SCROLL_THRESHOLD = 10;
  private boolean isOnClick;
  
  ImageView mDragView;
  GestureDetector mGestureDetector;
  
  DropListener mDropListener;
  RemoveListener mRemoveListener;
  DragListener mDragListener;
  
  public DragNDropListView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }
  
  public void setDropListener(DropListener l) {
    mDropListener = l;
  }

  public void setRemoveListener(RemoveListener l) {
    mRemoveListener = l;
  }
  
  public void setDragListener(DragListener l) {
    mDragListener = l;
  }

  @Override
  public boolean onTouchEvent(MotionEvent ev) {
    final int action = ev.getAction();
    final int x = (int) ev.getX();
    final int y = (int) ev.getY();  
    
    if (action == MotionEvent.ACTION_DOWN && x < this.getWidth()/4) {
      mDragMode = true;
    }

    if (!mDragMode) 
      return super.onTouchEvent(ev);

    switch (action) {
      case MotionEvent.ACTION_DOWN:
        mStartPosition = pointToPosition(x,y);
        if (mStartPosition != INVALID_POSITION) {
          int mItemPosition = mStartPosition - getFirstVisiblePosition();
                    mDragPointOffset = y - getChildAt(mItemPosition).getTop();
                    mDragPointOffset -= ((int)ev.getRawY()) - y;
          startDrag(mItemPosition,y);
          drag(0,y);// replace 0 with x if desired
          isOnClick = true;
        }  
        break;
      case MotionEvent.ACTION_MOVE:
          if (isOnClick && (Math.abs(x - ev.getX()) > SCROLL_THRESHOLD || Math.abs(y - ev.getY()) > SCROLL_THRESHOLD)) {
                  isOnClick = false;
              }
        drag(0,y);// replace 0 with x if desired
        break;
      case MotionEvent.ACTION_CANCEL:
      case MotionEvent.ACTION_UP:
          if (isOnClick) {
                  mDragMode = false;
                  mEndPosition = pointToPosition(x,y);
                  stopDrag(mStartPosition - getFirstVisiblePosition());
                  if (mDropListener != null && mStartPosition != INVALID_POSITION && mEndPosition != INVALID_POSITION) 
                       mDropListener.onDrop(mStartPosition, mEndPosition);
                  return super.onTouchEvent(ev);
              }
      default:
        mDragMode = false;
        mEndPosition = pointToPosition(x,y);
        stopDrag(mStartPosition - getFirstVisiblePosition());
        if (mDropListener != null && mStartPosition != INVALID_POSITION && mEndPosition != INVALID_POSITION) 
               mDropListener.onDrop(mStartPosition, mEndPosition);
      
        break;
    }
    return true;
  }  
  
  // move the drag view
  private void drag(int x, int y) {
    if (mDragView != null) {
      WindowManager.LayoutParams layoutParams = (WindowManager.LayoutParams) mDragView.getLayoutParams();
      layoutParams.x = x;
      layoutParams.y = y - mDragPointOffset;
      WindowManager mWindowManager = (WindowManager) getContext()
          .getSystemService(Context.WINDOW_SERVICE);
      mWindowManager.updateViewLayout(mDragView, layoutParams);

      if (mDragListener != null)
        mDragListener.onDrag(x, y, null);// change null to "this" when ready to use
    }
  }

  // enable the drag view for dragging
  private void startDrag(int itemIndex, int y) {
    stopDrag(itemIndex);

    View item = getChildAt(itemIndex);
    if (item == null) return;
    item.setDrawingCacheEnabled(true);
    if (mDragListener != null)
      mDragListener.onStartDrag(item);
    
        // Create a copy of the drawing cache so that it does not get recycled
        // by the framework when the list tries to clean up memory
        Bitmap bitmap = Bitmap.createBitmap(item.getDrawingCache());
        
        WindowManager.LayoutParams mWindowParams = new WindowManager.LayoutParams();
        mWindowParams.gravity = Gravity.TOP;
        mWindowParams.x = 0;
        mWindowParams.y = y - mDragPointOffset;

        mWindowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
        mWindowParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
        mWindowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
                | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
                | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN
                | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;
        mWindowParams.format = PixelFormat.TRANSLUCENT;
        mWindowParams.windowAnimations = 0;
        
        Context context = getContext();
        ImageView v = new ImageView(context);
        v.setImageBitmap(bitmap);      

        WindowManager mWindowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        mWindowManager.addView(v, mWindowParams);
        mDragView = v;
  }

  // destroy drag view
  private void stopDrag(int itemIndex) {
    if (mDragView != null) {
      if (mDragListener != null)
        mDragListener.onStopDrag(getChildAt(itemIndex));
            mDragView.setVisibility(GONE);
            WindowManager wm = (WindowManager)getContext().getSystemService(Context.WINDOW_SERVICE);
            wm.removeView(mDragView);
            mDragView.setImageDrawable(null);
            mDragView = null;
        }
  }

//  private GestureDetector createFlingDetector() {
//    return new GestureDetector(getContext(), new SimpleOnGestureListener() {
//            @Override
//            public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
//                    float velocityY) {           
//                if (mDragView != null) {                
//                  int deltaX = (int)Math.abs(e1.getX()-e2.getX());
//                  int deltaY = (int)Math.abs(e1.getY() - e2.getY());
//               
//                  if (deltaX > mDragView.getWidth()/2 && deltaY < mDragView.getHeight()) {
//                    mRemoveListener.onRemove(mStartPosition);
//                  }
//                  
//                  stopDrag(mStartPosition - getFirstVisiblePosition());
//
//                    return true;
//                }
//                return false;
//            }
//        });
//  }
}

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