Android下图片可拖动到任意位置的效果
下面为Activity的代码：
public class DraftTest extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sign);
DisplayMetrics dm = getResources().getDisplayMetrics();
final int screenWidth = dm.widthPixels;
final int screenHeight = dm.heightPixels - 50;
//拖动的按钮
final Button b=(Button)findViewById(R.id.startBtn);
//添加触摸事件
b.setOnTouchListener(new OnTouchListener(){
int lastX, lastY; //记录移动的最后的位置
public boolean onTouch(View v, MotionEvent event) {
//获取Action
int ea=event.getAction();
Log.i("TAG", "Touch:"+ea);
switch(ea){
case MotionEvent.ACTION_DOWN://按下
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
/**
* layout(l,t,r,b)
* lLeft position, relative to parent
tTop position, relative to parent
rRight position, relative to parent
bBottom position, relative to parent
* */
case MotionEvent.ACTION_MOVE://移动
//移动中动态设置位置
int dx =(int)event.getRawX() - lastX;
int dy =(int)event.getRawY() - lastY;
int left = v.getLeft() + dx;
int top = v.getTop() + dy;
int right = v.getRight() + dx;
int bottom = v.getBottom() + dy;
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);
Log.i("", "position：" + left +", " + top + ", " + right + ", " + bottom);
//将当前的位置再次设置
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
case MotionEvent.ACTION_UP://脱离
break;
}
return false;
}});
}
}
XML配置文件Sign.xml的代码:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/layoutRacingNeedForSpeed" android:padding="0px"
android:layout_width="fill_parent" android:layout_height="fill_parent">
<Button
android:id="@+id/startBtn"
android:text="tuodongdeanniu"
android:layout_centerInParent="true"
android:layout_width="wrap_content" android:layout_height="wrap_content"/>
</RelativeLayout>
这样就可以实现了~
