接下来的这个小例子演示当手指在触摸屏上拖动的时候，一个红色的小球更随手指进行移动。不过这个例子大致演示了一下自定义UI组件。
先来看看效果吧：
代码大致如下：
AndroidDemoActivity.java
package Android.Demo;
import android.app.Activity;
import android.os.Bundle;
import android.provider.ContactsContract.CommonDataKinds.Event;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.LinearLayout;
public class AndroidDemoActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
LinearLayout layout = (LinearLayout) findViewById(R.id.root);
final DrawView draw = new DrawView(this);
draw.setMinimumHeight(300);
draw.setMinimumWidth(300);
draw.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View arg0, MotionEvent evnet) {
// TODO Auto-generated method stub
draw.currentX = evnet.getX();
draw.currentY = evnet.getY();
draw.invalidate();
return false;
}
});
layout.addView(draw);
}
}
DrawView.java代码如下：
package Android.Demo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;
public class DrawView extends View {
public DrawView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint p = new Paint();
p.setColor(Color.RED);
canvas.drawCircle(currentX, currentY, 15, p);
}
public float currentX = 40;
public float currentY = 40;
}
main.xml代码如下：