实现拖动效果

http://www.roiding.com/index.php/archives/211

废话少说，要实现的效果就是在界面上拖动这一个按钮到处跑。

1. 布局文件

<?
xml
 
version
=
"1.0"
 
encoding
=
"utf-8"
?>
<
LinearLayout
 
xmlns:android
=
"http://schemas.android.com/apk/res/android"
android:orientation
=
"vertical"
 
android:layout_width
=
"fill_parent"
android:layout_height
=
"fill_parent"
>
<
Button
 
android:id
=
"@+id/btn_hello"
 
android:layout_width
=
"fill_parent"
android:layout_height
=
"wrap_content"
 
android:text
=
"@string/hello"
 
/>
</
LinearLayout
>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:id="@+id/btn_hello" android:layout_width="fill_parent"
android:layout_height="wrap_content" android:text="@string/hello" />
</LinearLayout>

2. 代码

package
 com.roiding.sample;

import
 android.app.Activity;
import
 android.os.Bundle;
import
 android.util.Log;
import
 android.view.MotionEvent;
import
 android.view.View;
import
 android.view.View.OnTouchListener;
import
 android.widget.Button;

public
 
class
 Touch 
extends
 Activity {
/** Called when the activity is first created. */
@Override
public
 
void
 onCreate(Bundle savedInstanceState) {
super
.onCreate(savedInstanceState);
setContentView(R.layout.main);

final
 Button btn = (Button) findViewById(R.id.btn_hello);

btn.setOnTouchListener(new
 OnTouchListener() {
int
[] temp = 
new
 
int
[] { 
0
, 
0
 };

public
 
boolean
 onTouch(View v, MotionEvent event) {

int
 eventaction = event.getAction();
Log.i("&&&"
, 
"onTouchEvent:"
 + eventaction);

int
 x = (
int
) event.getRawX();
int
 y = (
int
) event.getRawY();

switch
 (eventaction) {

case
 MotionEvent.ACTION_DOWN: 
// touch down so check if the
temp[0
] = (
int
) event.getX();
temp[1
] = y - v.getTop();
break
;

case
 MotionEvent.ACTION_MOVE: 
// touch drag with the ball
v.layout(x - temp[0
], y - temp[
1
], x + v.getWidth()
- temp[0
], y - temp[
1
] + v.getHeight());

v.postInvalidate();
break
;

case
 MotionEvent.ACTION_UP:
break
;
}

return
 
false
;
}

});

}
}