Android 的 View 通常都是定义在 layout 目录下的 .xml 文件中,但是 Android 应用程序也支持使用继承自 View 的类来动态创建 View. 今天写了一个很简单的游戏例子,演示自定义 View 的使用。游戏非常简单,界面上的红色圆球会随着鼠标的移动而移动。
UserDefineViewActivity
package com.example.androidexample;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.LinearLayout;
public class UserDefineViewActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_draw);
LinearLayout layout = (LinearLayout)findViewById(R.id.DrawLayout);
final DrawView drawView = new DrawView(this);
layout.setMinimumHeight(500);
layout.setMinimumWidth(300);
drawView.setOnTouchListener(new OnTouchListener(){
@Override
public boolean onTouch(View view, MotionEvent event) {
// TODO Auto-generated method stub
drawView.currentX = event.getX();
drawView.currentY = event.getY();
drawView.invalidate();
return true;
}
});
layout.addView(drawView);
}
}
package com.example.androidexample;
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 float currentX;
public float currentY;
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(Color.RED);
canvas.drawCircle(currentX, currentY, 15, paint);
}
public DrawView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/DrawLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
</LinearLayout>