tasks/src/main/java/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.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 org.tasks.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 float mDragStartX;
	private DropListener mDropListener;
	private int mUpperBound;
	private int mLowerBound;
	private int mHeight;
	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;
	private Thread longPressThread;

	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
	final public void addHeaderView (View v, Object data, boolean isSelectable) {
		throw new RuntimeException("Headers are not supported with TouchListView");
	}

	@Override
	final public void addHeaderView (View v) {
		throw new RuntimeException("Headers are not supported with TouchListView");
	}

  @Override
  final public void addFooterView (View v, Object data, boolean isSelectable) {
    if (mRemoveMode == SLIDE_LEFT || mRemoveMode == SLIDE_RIGHT) {
      throw new RuntimeException("Footers are not supported with TouchListView in conjunction with remove_mode");
    }
  }

  @Override
  final public void addFooterView (View v) {
    if (mRemoveMode == SLIDE_LEFT || mRemoveMode == SLIDE_RIGHT) {
      throw new RuntimeException("Footers are not supported with TouchListView in conjunction with remove_mode");
    }
  }

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
			if (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;
									}

									View item = getChildAt(itemnum - getFirstVisiblePosition());

									if (isDraggableRow(item)) {
										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());
												item.setDrawingCacheEnabled(false);

												Rect listBounds=new Rect();

												getGlobalVisibleRect(listBounds, null);

												startDragging(bitmap, listBounds.left, y);
												mDragPos = itemnum;
												mFirstDragPos = mDragPos;
												mHeight = getHeight();
												mDragStartX = ev.getX();

												int touchSlop = mTouchSlop;
												mUpperBound = Math.min(y - touchSlop, mHeight / 3);
												mLowerBound = Math.max(y + touchSlop, mHeight * 2 /3);
												return false;
										}

										mDragView = null;
									}

									break;
					}
			}
			return super.onInterceptTouchEvent(ev);
	}

	protected boolean isDraggableRow(View view) {
    return(view.findViewById(grabberId)!=null);
	}

	/*
	 * 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 - (mItemHeightNormal/2);
			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) {
									// 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;
							}
					}

					if (isDraggableRow(v)) {
						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;
							}
					}

					if (isDraggableRow(vv)) {
						ViewGroup.LayoutParams params = vv.getLayoutParams();
						params.height = height;
						vv.setLayoutParams(params);
						vv.setVisibility(visibility);
					}
			}
			// Request re-layout since we changed the items layout
			// and not doing this would cause bogus hitbox calculation
			// in myPointToPosition
			layoutChildren();
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
			if ((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) {
											unExpandViews(true);
									} else if (mDragPos == mFirstDragPos && ev.getX() < mDragStartX - 20) {
											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) {
													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 x, int y) {
			stopDragging();

			mWindowParams = new WindowManager.LayoutParams();
			mWindowParams.gravity = Gravity.TOP|Gravity.LEFT;
			mWindowParams.x = x;
			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());
			v.setBackgroundColor(dragndropBackgroundColor);
			v.setImageBitmap(bm);
			mDragBitmap = bm;

			mWindowManager = (WindowManager)getContext().getSystemService(Context.WINDOW_SERVICE);
			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 (mDragBitmap != null) {
            mDragBitmap.recycle();
            mDragBitmap = null;
        }

        if (mDragView != null) {
            WindowManager wm = (WindowManager) getContext().getSystemService(
                    Context.WINDOW_SERVICE);
            wm.removeView(mDragView);
            mDragView.setImageDrawable(null);
            mDragView = null;
        }

        if(longPressThread != null) {
            longPressThread.interrupt();
            longPressThread = null;
        }
    }

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

	public interface GrabberClickListener {
	    public void onClick(View v);
	    public void onLongClick(View v);
	}

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