Question

android怎么实现 图像随着手指的移动而移动

Answer 1

activity内容：

Java code
?

public class CustomView extends Activity
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}

DrawView组件：

Java code
?

public class DrawView extends View
{
public float currentX = 40;
public float currentY = 50;
/**
* @param context
*/
public DrawView(Context context , AttributeSet set)
{
super(context , set);
}
@Override
public void onDraw (Canvas canvas)
{
super.onDraw(canvas);
//创建画笔
Paint p = new Paint();
//设置画笔的颜色
p.setColor(Color.RED);
//绘制一个小圆（作为小球）
canvas.drawCircle(currentX , currentY , 15 , p);
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
//当前组件的currentX、currentY两个属性
this.currentX = event.getX();
this.currentY = event.getY();
//通知改组件重绘
this.invalidate();
//返回true表明处理方法已经处理该事件
return true;
}
}

xml布局文件：

XML/HTML code
?

<?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"
>
<!-- 使用自定义组件 -->
<org.crazyit.event.DrawView
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
</LinearLayout>