android canvas使用line画半圆

本文实例为大家分享了android canvas使用line画半圆具体代码，供大家参考，具体内容如下

LineView.java

public class LineView extends View {
  private int progress = 0;
  private int max = 100;
  private int roundWidth = 50;
  public LineView(Context context) {
    super(context);
  }

  public LineView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  public LineView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
  }

  public void setProgress(int progress) {
    this.progress = progress;
    invalidate();
  }

  @Override
  protected void onDraw(Canvas canvas) {

    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setColor(Color.RED);

    paint.setStrokeWidth(roundWidth);
    paint.setStyle(Paint.Style.STROKE);

    canvas.drawCircle(getWidth() / 2, getHeight() / 2, 200, paint);

    paint.setStyle(Paint.Style.FILL);
    paint.setStrokeWidth(10);
    paint.setColor(Color.BLUE);
    int startX = 0, startY = 0, stopX = 0, stopY = 0;

    startX=0;
    stopX=500;
    for (int i = 0; i <= progress; i++) {
      startY = stopY = getHeight()/2+200-roundWidth/2 - i*(400-roundWidth)/max;
      double v = Math.pow((200 - roundWidth / 2), 2) - (Math.pow((startY-getHeight()/2), 2));
      startX = (int)(getWidth()/2-Math.sqrt(v));
      stopX = (int)(getWidth()/2+Math.sqrt(v));
      canvas.drawLine(startX, startY, stopX, stopY, paint);
    }
  }
}

MainActivity.java

public class MainActivity extends Activity {

  private LineView lv;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    lv = (LineView)findViewById(R.id.lv);

    lv.setonClickListener(new View.onClickListener() {
      @Override
      public void onClick(View v) {
 lv.setEnabled(false);


 new Thread() {
   @Override
   public void run() {
     for (int i = 0; i <= 100; i++) {

final int finalI = i;
runonUiThread(new Runnable() {
  @Override
  public void run() {
    lv.setProgress(finalI);
  }
});
try {
  sleep(10);
} catch (InterruptedException e) {
  e.printStackTrace();
}
     }

     runonUiThread(new Runnable() {
@Override
public void run() {
  lv.setEnabled(true);
}
     });
   }
 }.start();

      }
    });
  }
}

activity_main.xml

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。