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  • Android开发——跟随手指的小球实现

     

    今天要实现的是一个跟随手指的小球,说白了就是让小球按着手指滑动的轨迹运动,实现起来还是比较容易的。

    用到的类是drawView,我们先自定义一个DrawView组件。

    DrawView.java:

                  

    package cn.csdn.android.view;

    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 = 300;
     public float currentY = 500;
     
     public DrawView(Context context) {
      super(context);
      // TODO Auto-generated constructor stub
     }

     @Override
     protected void onDraw(Canvas canvas) {
      // TODO Auto-generated method stub
      super.onDraw(canvas);
      Paint p = new Paint();
      p.setColor(Color.RED);
      canvas.drawCircle(currentX, currentY, 15, p);
     }
     
     
    }

    ==================================

    在main.xml文件中给一个android:id="@+id/root";

    然后写java代码实现跟踪效果:

    CustomView.java

    package cn.csdn.android.view;

    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 CustomViewActivity extends Activity{

     @Override
     protected void onCreate(Bundle savedInstanceState) {
      // TODO Auto-generated method stub
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      
      LinearLayout main = (LinearLayout) findViewById(R.id.root);
      final DrawView draw = new DrawView(this);
         draw.setMinimumWidth(300);
         draw.setMinimumHeight(500);
        
         draw.setOnTouchListener(new OnTouchListener() {
       
       @Override
       public boolean onTouch(View v, MotionEvent event) {
        draw.currentX = event.getX();
        draw.currentY = event.getY();
        draw.invalidate();
        return true;
       }
      });
         main.addView(draw);
     }
     
    }

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  • 原文地址:https://www.cnblogs.com/xgjblog/p/3897916.html
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