Android拖动实现很简单，主要就是实现OnTouchListener事件监听，获取到触碰点之后，重新设置View的位置即可。
下面是这个例子的描述：
首先点击create按钮，将会产生一个新的ImageView对象，然后移动新的ImageView到任何你想要去的地方。如下图：
下面是源码：
创建一个新的View，并添加到Window中：
package com.mandr.test;
import android.content.Context;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class CreatView {
public static final String Tag = 'CreatView';
private Context mContext;
protected static CreatView mCreatView;
private int[] location;
private ImageView mImageView;
public WindowManager mWm;
public WindowManager.LayoutParams layoutParams;
public CreatView(Context context)
{
this.mContext = context;
mWm = (WindowManager)
mContext.getSystemService(Context.WINDOW_SERVICE);
layoutParams = new
WindowManager.LayoutParams();
}
public synchronized static CreatView
getCreatView(Context context) {
Log.d(Tag, 'getCreatView');
if (mCreatView == null) {
mCreatView = new CreatView(context);
}
return mCreatView;
}
public void setLocation(int[]
location) {
this.location = location;
}
private View createNewView() {
Log.d(Tag, 'createNewView');
ImageView mImageView = new
ImageView(mContext);
mImageView.setImageDrawable(mContext.getResources().getDrawable(
R.drawable.apple));
mImageView.setLayoutParams(new
LinearLayout.LayoutParams(40, 40));
return mImageView;
}
public void addViewToScreen() {
Log.d(Tag, 'addViewToScreen');
mImageView = (ImageView) createNewView();
mImageView.setOnTouchListener(new
TouchListener());
layoutParams.gravity =
Gravity.LEFT | Gravity.TOP;
layoutParams.x = location[0] + 30; //偏移量x
layoutParams.y = location[1];
//偏移量y
layoutParams.width = 40;
layoutParams.height = 40;
layoutParams.alpha = 1.0f;
mWm.addView(mImageView, layoutParams);
}
class TouchListener implements
OnTouchListener {
int lastX;
int lastY;
int screenWidth;
int screenHeight;
public TouchListener() {
DisplayMetrics dm =
mContext.getResources().getDisplayMetrics();
screenWidth = dm.widthPixels;
screenHeight = dm.heightPixels;
Log.d(Tag, 'screen width =' + screenWidth +
',screen height='
+ screenHeight);
}
@Override
public boolean onTouch(View v, MotionEvent event)
{
Log.d(Tag, 'TouchListener --
onTouch');
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
Log.d(Tag, 'down x=' + lastX + ',
y=' + lastY);
break;
case MotionEvent.ACTION_MOVE:
int dx = (int) event.getRawX() -
lastX;
int dy = (int) event.getRawY() -
lastY;
Log.d(Tag, 'move dx=' + dx + ',
dy=' + dy);
int left = v.getLeft() + dx;
int top = v.getTop() + dy;
int right = v.getRight() + dx;
int bottom = v.getBottom() +
dy;
Log.d(Tag, 'view left=' +
left + ', top=' + top + ', right='
+ right + ',bottom='
+ bottom);
// set bound
if (left < 0) {
left = 0;
right = left +
v.getWidth();
}
if (right > screenWidth) {
right = screenWidth;
left = right -
v.getWidth();
}
if (top < 0) {
top = 0;
bottom = top +
v.getHeight();
}
if (bottom > screenHeight)
{
bottom = screenHeight;
top = bottom -
v.getHeight();
}
v.layout(left,
top, right, bottom);
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
layoutParams.x = lastX;
layoutParams.y = lastY-30;
mWm.updateViewLayout(v,
layoutParams);
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
}
}
测试的Activity：
package com.mandr.test;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity
{
public static final String Tag =
'MainActivity';
private Button creatorBtn;
private CreatView mCreatView;
@Override
public void onCreate(Bundle
savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mCreatView
= CreatView.getCreatView(this);
creatorBtn
= (Button)this.findViewById(R.id.button1);
creatorBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(Tag, 'creatorBtn
click');
int[] location = new int[2];
v.getLocationInWindow(location);
Log.d(Tag, 'x = '+location[0]+',y =
'+location[1]);
mCreatView.setLocation(location);
mCreatView.addViewToScreen();
}
});
}
}
触控事件的处理，例如照片的放大和缩小，桌面ICON的删除等等，应用也是很广泛的，希望我能和大家一起学习，成长。
