tasks/astrid/common-src/com/commonsware/cwac/tlv/TouchListView.java

/*
 * Copyright (c) 2010 CommonsWare, LLC
 * Portions Copyright (C) 2008 The Android Open Source Project
 *
 * 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.
 */

package com.commonsware.cwac.tlv;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;

import com.timsu.astrid.R;

public class TouchListView extends ListView {
	private ImageView mDragView;
	private WindowManager mWindowManager;
	private WindowManager.LayoutParams mWindowParams;
	private int mDragPos;      // which item is being dragged
	private int mFirstDragPos; // where was the dragged item originally
	private int mDragPoint;    // at what offset inside the item did the user grab it
	private int mCoordOffset;  // the difference between screen coordinates and coordinates in this view
	private int mDragStartX;
	private DragListener mDragListener;
	private DropListener mDropListener;
	private SwipeListener mSwipeListener;
	private int mUpperBound;
	private int mLowerBound;
	private int mHeight;
	private GestureDetector mGestureDetector;
	public static final int FLING = 0;
	public static final int SLIDE_RIGHT = 1;
	public static final int SLIDE_LEFT = 2;
	private int mRemoveMode = -1;
	private final Rect mTempRect = new Rect();
	private Bitmap mDragBitmap;
	private final int mTouchSlop;
	private int mItemHeightNormal=-1;
	private int mItemHeightExpanded=-1;
	private int grabberId=-1;
	private int dragndropBackgroundColor=0x00000000;

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

	public TouchListView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);

		mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();

		if (attrs!=null) {
			TypedArray a=getContext()
										.obtainStyledAttributes(attrs,
																							R.styleable.TouchListView,
																							0, 0);

			mItemHeightNormal=a.getDimensionPixelSize(R.styleable.TouchListView_normal_height, 0);
			mItemHeightExpanded=a.getDimensionPixelSize(R.styleable.TouchListView_expanded_height, mItemHeightNormal);
			grabberId=a.getResourceId(R.styleable.TouchListView_grabber, -1);
			dragndropBackgroundColor=a.getColor(R.styleable.TouchListView_dragndrop_background, 0x00000000);
			mRemoveMode=a.getInt(R.styleable.TouchListView_remove_mode, -1);

			a.recycle();
		}
  }

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
			if (mDragListener != null || mDropListener != null) {
					switch (ev.getAction()) {
							case MotionEvent.ACTION_DOWN:
									int x = (int) ev.getX();
									int y = (int) ev.getY();
									int itemnum = pointToPosition(x, y);
									if (itemnum == AdapterView.INVALID_POSITION) {
											break;
									}
									ViewGroup item = (ViewGroup) getChildAt(itemnum - getFirstVisiblePosition());
									mDragPoint = y - item.getTop();
									mCoordOffset = ((int)ev.getRawY()) - y;
									View dragger = item.findViewById(grabberId);
									Rect r = mTempRect;
//									dragger.getDrawingRect(r);

									r.left=dragger.getLeft();
									r.right=dragger.getRight();
									r.top=dragger.getTop();
									r.bottom=dragger.getBottom();

									if ((r.left<x) && (x<r.right)) {
											item.setDrawingCacheEnabled(true);
											// 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());
											startDragging(bitmap, y);
											mDragPos = itemnum;
											mFirstDragPos = mDragPos;
											mHeight = getHeight();
											int touchSlop = mTouchSlop;
											mUpperBound = Math.min(y - touchSlop, mHeight / 3);
											mLowerBound = Math.max(y + touchSlop, mHeight * 2 /3);
											mDragStartX = x;
											return false;
									}
									mDragView = null;
									break;
					}
			}
			return super.onInterceptTouchEvent(ev);
	}

	/*
	 * pointToPosition() doesn't consider invisible views, but we
	 * need to, so implement a slightly different version.
	 */
	private int myPointToPosition(int x, int y) {
			Rect frame = mTempRect;
			final int count = getChildCount();
			for (int i = count - 1; i >= 0; i--) {
					final View child = getChildAt(i);
					child.getHitRect(frame);
					if (frame.contains(x, y)) {
							return getFirstVisiblePosition() + i;
					}
			}
			return INVALID_POSITION;
	}

	private int getItemForPosition(int y) {
			int adjustedy = y - mDragPoint - 32;
			int pos = myPointToPosition(0, adjustedy);
			if (pos >= 0) {
					if (pos <= mFirstDragPos) {
							pos += 1;
					}
			} else if (adjustedy < 0) {
					pos = 0;
			}
			return pos;
	}

	private void adjustScrollBounds(int y) {
			if (y >= mHeight / 3) {
					mUpperBound = mHeight / 3;
			}
			if (y <= mHeight * 2 / 3) {
					mLowerBound = mHeight * 2 / 3;
			}
	}

	/*
	 * Restore size and visibility for all listitems
	 */
	private void unExpandViews(boolean deletion) {
			for (int i = 0;; i++) {
					View v = getChildAt(i);
					if (v == null) {
							if (deletion && getCount() > 0) {
									// HACK force update of mItemCount
									int position = getFirstVisiblePosition();
									int y = getChildAt(0).getTop();
									setAdapter(getAdapter());
									setSelectionFromTop(position, y);
									// end hack
							}
							layoutChildren(); // force children to be recreated where needed
							v = getChildAt(i);
							if (v == null) {
									break;
							}
					}
					ViewGroup.LayoutParams params = v.getLayoutParams();
					params.height = mItemHeightNormal;
					v.setLayoutParams(params);
					v.setVisibility(View.VISIBLE);
			}
	}

	/* Adjust visibility and size to make it appear as though
	 * an item is being dragged around and other items are making
	 * room for it:
	 * If dropping the item would result in it still being in the
	 * same place, then make the dragged listitem's size normal,
	 * but make the item invisible.
	 * Otherwise, if the dragged listitem is still on screen, make
	 * it as small as possible and expand the item below the insert
	 * point.
	 * If the dragged item is not on screen, only expand the item
	 * below the current insertpoint.
	 */
	private void doExpansion() {
			int childnum = mDragPos - getFirstVisiblePosition();
			if (mDragPos > mFirstDragPos) {
					childnum++;
			}

			View first = getChildAt(mFirstDragPos - getFirstVisiblePosition());

			for (int i = 0;; i++) {
					View vv = getChildAt(i);
					if (vv == null) {
							break;
					}
					int height = mItemHeightNormal;
					int visibility = View.VISIBLE;
					if (vv.equals(first)) {
							// processing the item that is being dragged
							if (mDragPos == mFirstDragPos) {
									// hovering over the original location
									visibility = View.INVISIBLE;
							} else {
									// not hovering over it
									height = 1;
							}
					} else if (i == childnum) {
							if (mDragPos < getCount() - 1) {
									height = mItemHeightExpanded;
							}
					}
					ViewGroup.LayoutParams params = vv.getLayoutParams();
					params.height = height;
					vv.setLayoutParams(params);
					vv.setVisibility(visibility);
			}
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
			if (mGestureDetector != null) {
					mGestureDetector.onTouchEvent(ev);
			}
			if ((mDragListener != null || mDropListener != null) && mDragView != null) {
					int action = ev.getAction();
					switch (action) {
							case MotionEvent.ACTION_UP:
							case MotionEvent.ACTION_CANCEL:
									Rect r = mTempRect;
									mDragView.getDrawingRect(r);
									stopDragging();
									if (mDragPos == mFirstDragPos && ev.getX() > mDragStartX + 20) {
											if (mSwipeListener!= null) {
													mSwipeListener.swipeRight(mFirstDragPos);
											}
											unExpandViews(true);
									} else if (mDragPos == mFirstDragPos && ev.getX() < mDragStartX - 20) {
    									    if (mSwipeListener!= null) {
    									        mSwipeListener.swipeLeft(mFirstDragPos);
    									    }
											unExpandViews(true);
									} else {
											if (mDropListener != null && mDragPos >= 0 && mDragPos < getCount()) {
													mDropListener.drop(mFirstDragPos, mDragPos);
											}
											unExpandViews(false);
									}
									break;

							case MotionEvent.ACTION_DOWN:
							case MotionEvent.ACTION_MOVE:
									int x = (int) ev.getX();
									int y = (int) ev.getY();
									dragView(x, y);
									int itemnum = getItemForPosition(y);
									if (itemnum >= 0) {
											if (action == MotionEvent.ACTION_DOWN || itemnum != mDragPos) {
													if (mDragListener != null) {
															mDragListener.drag(mDragPos, itemnum);
													}
													mDragPos = itemnum;
													doExpansion();
											}
											int speed = 0;
											adjustScrollBounds(y);
											if (y > mLowerBound) {
													// scroll the list up a bit
													speed = y > (mHeight + mLowerBound) / 2 ? 16 : 4;
											} else if (y < mUpperBound) {
													// scroll the list down a bit
													speed = y < mUpperBound / 2 ? -16 : -4;
											}
											if (speed != 0) {
													int ref = pointToPosition(0, mHeight / 2);
													if (ref == AdapterView.INVALID_POSITION) {
															//we hit a divider or an invisible view, check somewhere else
															ref = pointToPosition(0, mHeight / 2 + getDividerHeight() + 64);
													}
													View v = getChildAt(ref - getFirstVisiblePosition());
													if (v!= null) {
															int pos = v.getTop();
															setSelectionFromTop(ref, pos - speed);
													}
											}
									}
									break;
					}
					return true;
			}
			return super.onTouchEvent(ev);
	}

	private void startDragging(Bitmap bm, int y) {
			stopDragging();

			mWindowParams = new WindowManager.LayoutParams();
			mWindowParams.gravity = Gravity.TOP;
			mWindowParams.x = 0;
			mWindowParams.y = y - mDragPoint + mCoordOffset;

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

			ImageView v = new ImageView(getContext());
//        int backGroundColor = getContext().getResources().getColor(R.color.dragndrop_background);
			v.setBackgroundColor(dragndropBackgroundColor);
			v.setImageBitmap(bm);
			mDragBitmap = bm;

			mWindowManager = (WindowManager)getContext().getSystemService("window"); //$NON-NLS-1$
			mWindowManager.addView(v, mWindowParams);
			mDragView = v;
	}

	private void dragView(int x, int y) {
			float alpha = 1.0f;
			int width = mDragView.getWidth();

			if (mRemoveMode == SLIDE_RIGHT) {
					if (x > width / 2) {
							alpha = ((float)(width - x)) / (width / 2);
					}
					mWindowParams.alpha = alpha;
			}
			else if (mRemoveMode == SLIDE_LEFT) {
					if (x < width / 2) {
							alpha = ((float)x) / (width / 2);
					}
					mWindowParams.alpha = alpha;
			}
			mWindowParams.y = y - mDragPoint + mCoordOffset;
			mWindowManager.updateViewLayout(mDragView, mWindowParams);
	}

	private void stopDragging() {
			if (mDragView != null) {
					WindowManager wm = (WindowManager)getContext().getSystemService("window"); //$NON-NLS-1$
					wm.removeView(mDragView);
					mDragView.setImageDrawable(null);
					mDragView = null;
			}
			if (mDragBitmap != null) {
					mDragBitmap.recycle();
					mDragBitmap = null;
			}
	}

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

	public void setDropListener(DropListener l) {
			mDropListener = l;
	}

	public void setSwipeListener(SwipeListener l) {
			mSwipeListener = l;
	}

	public interface DragListener {
			void drag(int from, int to);
	}
	public interface DropListener {
			void drop(int from, int to);
	}
	public interface SwipeListener {
			void swipeLeft(int which);
			void swipeRight(int which);
	}
}