Android开发实现跟随手指的小球效果示例

2019-12-12 00:13:25

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本文实例讲述了Android开发实现跟随手指的小球效果。分享给大家供大家参考，具体如下：

配置DrawView类用于绘制小球

public class DrawView extends View {  public float currentX = 40;  public float currentY = 50;  //定义并创建画笔  Paint p = new Paint();  public DrawView(Context context)  {    super(context);  }  public DrawView(Context context , AttributeSet set)  {    super(context,set);  }  @Override  public void onDrawForeground(Canvas canvas) {    super.onDrawForeground(canvas);    //设置画笔颜色    p.setColor(Color.RED);    //绘制一个小球    canvas.drawCircle(currentX , currentY , 30 , p);  }  //为组建的触碰实践重写处理方法  @Override  public boolean onTouchEvent(MotionEvent event) {    //修改currentX,currentY的两个属性    currentX = event.getX();    currentY = event.getY();    //通知当前组建重绘自己    invalidate();    //放回true表明该处理方法已经处理该事件    return true;  }}

MainActivity

public class MainActivity extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //获取Linearlayout布局容器    LinearLayout root = (LinearLayout) findViewById(R.id.root);    //创建DrawView组件    final DrawView draw = new DrawView(this);    //设定自定义组件的最小宽度、高度    draw.setMinimumWidth(300);    draw.setMinimumHeight(500);    root.addView(draw);  }}

xml文件

<?xml version="1.0" encoding="utf-8"?><LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:app="http://schemas.android.com/apk/res-auto"  xmlns:tools="http://schemas.android.com/tools"  android:id="@+id/root"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical">  <com.example.a30797.myapplication.DrawView    android:layout_width="match_parent"    android:layout_height="match_parent" /></LinearLayout>

**注：**由上面布局，已经添加了自定义组件，因此Activity代码可简化为：

public class MainActivity extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);  }}

示例：