android 中的椭圆是什么意思

Android中的椭圆是指一个形状类似于椭圆的图形。椭圆是一种闭合曲线，其特点是离两个焦点的距离之和是固定值。在Android中，我们可以使用椭圆来绘制各种图形，如按钮、背景、进度条等。本文将介绍Android中椭圆的使用方法，并提供一些实例代码来帮助读者更好地理解。

java
@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Paint paint = new Paint();
    paint.setColor(Color.RED);
    paint.setStyle(Paint.Style.FILL);
    RectF rectF = new RectF(100, 100, 500, 300);
    canvas.drawOval(rectF, paint);
}

java
@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Paint paint = new Paint();
    paint.setColor(Color.RED);
    paint.setStyle(Paint.Style.FILL);
    RectF rectF = new RectF(100, 100, 500, 300);
    canvas.drawOval(rectF, paint);
    paint.setColor(Color.WHITE);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(5);
    canvas.drawOval(rectF, paint);
}

java
public class OvalButton extends AppCompatButton {
    private Paint mPaint;
    private RectF mRectF;
    public OvalButton(Context context) {
        super(context);
        init();
    }
    public OvalButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }
    private void init() {
        mPaint = new Paint();
        mPaint.setColor(Color.RED);
        mPaint.setStyle(Paint.Style.FILL);
        mRectF = new RectF();
    }
    @Override
    protected void onDraw(Canvas canvas) {
        mRectF.set(0, 0, getWidth(), getHeight());
        canvas.drawOval(mRectF, mPaint);
        super.onDraw(canvas);
    }
}