android中拖动ListItem的源代码。

/* * 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.and.DragListView; import android.content.Context; import android.content.SharedPreferences; import android.content.res.Resources; import android.graphics.Bitmap; import android.graphics.PixelFormat; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.util.AttributeSet; import android.view.GestureDetector; import android.view.GestureDetector.SimpleOnGestureListener; 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; public class TouchListView extends ListView { private ImageView mDragView; private WindowManager mWindowManager; private WindowManager.LayoutParams mWindowParams; /** * At which position is the item currently being dragged. Note that this * takes in to account header items. */ private int mDragPos; /** * At which position was the item being dragged originally */ private int mSrcDragPos; private int mDragPointX; // at what x offset inside the item did the user grab it private int mDragPointY; // at what y offset inside the item did the user grab it private int mXOffset; // the difference between screen coordinates and coordinates in this view private int mYOffset; // the difference between screen coordinates and coordinates in this view private DragListener mDragListener; private DropListener mDropListener; private RemoveListener mRemoveListener; private int mUpperBound; private int mLowerBound; private int mHeight; private GestureDetector mGestureDetector; private static final int FLING = 0; private static final int SLIDE = 1; private static final int TRASH = 2; private int mRemoveMode = -1; private Rect mTempRect = new Rect(); private Bitmap mDragBitmap; private final int mTouchSlop; private int mItemHeightNormal; private int mItemHeightExpanded; private int mItemHeightHalf; private Drawable mTrashcan; public TouchListView(Context context) { this(context, null); } public TouchListView(Context context, AttributeSet attrs) { super(context, attrs); SharedPreferences pref = context.getSharedPreferences("Music", 3); mRemoveMode = pref.getInt("deletemode", -1); mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); Resources res = getResources(); mItemHeightNormal = res.getDimensionPixelSize(R.dimen.normal_height); mItemHeightHalf = mItemHeightNormal / 2; mItemHeightExpanded = res.getDimensionPixelSize(R.dimen.expanded_height); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { if (mRemoveListener != null && mGestureDetector == null) { if (mRemoveMode == FLING) { mGestureDetector = new GestureDetector(getContext(), new SimpleOnGestureListener() { @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { if (mDragView != null) { if (velocityX > 1000) { Rect r = mTempRect; mDragView.getDrawingRect(r); if ( e2.getX() > r.right * 2 / 3) { // fast fling right with release near the right edge of the screen stopDragging(); mRemoveListener.remove(mSrcDragPos); unExpandViews(true); } } // flinging while dragging should have no effect return true; } return false; } }); } } 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()); mDragPointX = x - item.getLeft(); mDragPointY = y - item.getTop(); mXOffset = ((int)ev.getRawX()) - x; mYOffset = ((int)ev.getRawY()) - y; // The left side of the item is the grabber for dragging the item if (x < 64) { 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, x, y); mDragPos = itemnum; mSrcDragPos = mDragPos; mHeight = getHeight(); int touchSlop = mTouchSlop; mUpperBound = Math.min(y - touchSlop, mHeight / 3); mLowerBound = Math.max(y + touchSlop, mHeight * 2 /3); return false; } stopDragging(); 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) { if (y < 0) { // when dragging off the top of the screen, calculate position // by going back from a visible item int pos = myPointToPosition(x, y + mItemHeightNormal); if (pos > 0) { return pos - 1; } } 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 - mDragPointY - mItemHeightHalf; int pos = myPointToPosition(0, adjustedy); if (pos >= 0) { if (pos <= mSrcDragPos) { pos += 1; } } else if (adjustedy < 0) { // this shouldn't happen anymore now that myPointToPosition deals // with this situation pos = 0; } return pos; } private void adjustScrollBounds(int y) { if (y >= mHeight / 3) { mUpperBound = mHeight / 3; }