android listview拖拽，拖动item 改变位置

转自：http://blog.csdn.net/dany1202/article/details/6109160#comments

在packages/apps/Music/src/touchIncepter.java中

该类提供了listview的拖动效果，并提供接口，在程序接口中实现数据的交换即可。

[java] view
plaincopy

package com.and.DragListview;



import java.util.ArrayList;

import java.util.List;



import android.app.ListActivity;

import android.content.Context;

import android.os.Bundle;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.ImageView;

import android.widget.TextView;



public class DragListview extends ListActivity {

MyAdapter adapter;

TouchInterceptor list;

List<String> arrayText;



@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);



list = (TouchInterceptor) getListView();//(TouchInterceptor)findViewById(android.R.id.list);

getText();



adapter = new MyAdapter(this);

setListAdapter(adapter);



list.setDropListener(mDropListener);

// list.setRemoveListener(mRemoveListener);

}

public void getText(){

arrayText = new ArrayList<String>();

arrayText.add("传奇");

arrayText.add("红豆");

arrayText.add("流年");

arrayText.add("棋子");

}



//交换listview的数据

private TouchInterceptor.DropListener mDropListener =

new TouchInterceptor.DropListener() {

public void drop(int from, int to) {

String item = arrayText.get(from);

arrayText.remove(item);//.remove(from);

arrayText.add(to, item);

adapter.notifyDataSetChanged();

}

};



private TouchInterceptor.RemoveListener mRemoveListener =

new TouchInterceptor.RemoveListener() {

public void remove(int which) {

}

};



class MyAdapter extends BaseAdapter{

private LayoutInflater mInflater;

Context mContext;

public MyAdapter(Context c){

mInflater = LayoutInflater.from(c);

}

public int getCount() {

return arrayText.size();

}



public Object getItem(int arg0) {

return arrayText.get(arg0);

}



public long getItemId(int arg0) {

return arg0;

}



public View getView(int arg0, View contentView, ViewGroup arg2) {

ImageView img;

TextView text;

if(contentView==null){

contentView = mInflater.inflate(R.layout.list_layout, null);

//contentView = mInflater.inflate(R.layout.list_layout,null);

}

img = (ImageView)contentView.findViewById(R.id.img);

img.setBackgroundResource(R.drawable.icon);

text = (TextView)contentView.findViewById(R.id.text);

text.setText(arrayText.get(arg0).toString());



return contentView;

}



}

}

源码中的类：

[java] view
plaincopy

/*

* 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.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.view.GestureDetector.SimpleOnGestureListener;

import android.widget.AdapterView;

import android.widget.ImageView;

import android.widget.ListView;



public class TouchInterceptor 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 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 int mRemoveMode = -1;

private Rect mTempRect = new Rect();

private Bitmap mDragBitmap;

private final int mTouchSlop;

private int mItemHeightNormal;

private int mItemHeightExpanded;

private int mItemHeightHalf;



public TouchInterceptor(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 = 48;//res.getDimensionPixelSize(R.dimen.normal_height);

mItemHeightHalf = mItemHeightNormal / 2;

mItemHeightExpanded = 96;//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(mFirstDragPos);

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());

mDragPoint = y - item.getTop();

mCoordOffset = ((int)ev.getRawY()) - y;

View dragger = item.findViewById(R.id.img);//..........................

Rect r = mTempRect;

dragger.getDrawingRect(r);

// The dragger icon itself is quite small, so pretend the touch area is bigger

if (x < r.right * 2) {

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);

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 - mDragPoint - mItemHeightHalf;

int pos = myPointToPosition(0, adjustedy);

if (pos >= 0) {

if (pos <= mFirstDragPos) {

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;

}

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;

}

}

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 (mRemoveMode == SLIDE && ev.getX() > r.right * 3 / 4) {

if (mRemoveListener != null) {

mRemoveListener.remove(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

| WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;

mWindowParams.format = PixelFormat.TRANSLUCENT;

mWindowParams.windowAnimations = 0;



Context context = getContext();

ImageView v = new ImageView(context);

// int backGroundColor = context.getResources().getColor(R.color.dragndrop_background);

// v.setBackgroundColor(backGroundColor);

v.setImageBitmap(bm);

mDragBitmap = bm;



mWindowManager = (WindowManager)context.getSystemService("window");

mWindowManager.addView(v, mWindowParams);

mDragView = v;

}



private void dragView(int x, int y) {

if (mRemoveMode == SLIDE) {

float alpha = 1.0f;

int width = mDragView.getWidth();

if (x > width / 2) {

alpha = ((float)(width - x)) / (width / 2);

}

mWindowParams.alpha = alpha;

}

if (mRemoveMode == FLING) {

mWindowParams.x = x;

}

mWindowParams.y = y - mDragPoint + mCoordOffset;

mWindowManager.updateViewLayout(mDragView, mWindowParams);

}



private void stopDragging() {

if (mDragView != null) {

WindowManager wm = (WindowManager)getContext().getSystemService("window");

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 setRemoveListener(RemoveListener l) {

mRemoveListener = l;

}



public interface DragListener {

void drag(int from, int to);

}

public interface DropListener {

void drop(int from, int to);

}

public interface RemoveListener {

void remove(int which);

}

}



<com.and.DragListview.TouchInterceptor

android:id="@android:id/list"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:textSize="18sp"

android:drawSelectorOnTop="false"

android:fastScrollEnabled="true" />

如果想要实现源码音乐播放器那种顺畅的拖动效果，则需注意2点：

1.<!-- height of a normal list item in edit playlist mode -->

<dimen name="normal_height">48dip</dimen>

<!-- height of an expanded list item in edit playlist mode -->

<dimen name="expanded_height">96dip</dimen>

后者的高度要为前者的2倍。

2.item对应的布局要在listview的item的bottom位置，即：

[java] view
plaincopy

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout

xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="match_parent"

android:layout_height="48dip">

<com.android.weather.CityListItemLayout

android:id="@+id/item_layout"

android:orientation="horizontal"

android:layout_width="match_parent"

android:layout_height="48dip"

android:gravity="center_vertical"

android:layout_alignParentBottom="true">

。。。

</com.android.weather.CityListItemLayout>

</RelativeLayout>