android - 如何在android中画一个半圆

Question

我正在使用此代码在我的应用中绘制一半:

  <?xml version="1.0" encoding="utf-8" ?>
<layer-list
    xmlns:android="http://schemas.android.com/apk/res/android"
    >
    <item
        android:left="35dp"
        android:top="40dp"
        android:bottom="40dp"
        android:right="0dp">
        <shape
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:shape="oval" android:innerRadius="30dp" android:thickness="0dp">
            <solid android:color="@color/transparent"/>
            <stroke android:width="3dp" android:color="@color/White"/>

        </shape>
    </item>
</layer-list>

输出:

但我需要像下面这样的东西:

这个怎么画？

Answer 1

我建议通过代码绘制。

1- 创建类 MyView 并放置下面的代码。

public class MyView extends View {

    public MyView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    @Override
    protected void onDraw(Canvas canvas) {

        // TODO Auto-generated method stub
        super.onDraw(canvas);
        float width = (float) getWidth();
        float height = (float) getHeight();
        float radius;

        if (width > height) {
         radius = height / 4;
        } else {
         radius = width / 4;
        }

        Path path = new Path();
        path.addCircle(width / 2,
         height / 2, radius,
         Path.Direction.CW);

        Paint paint = new Paint();
        paint.setColor(Color.BLACK);
        paint.setStrokeWidth(5);
        paint.setStyle(Paint.Style.FILL);

        float center_x, center_y;
        final RectF oval = new RectF();
        paint.setStyle(Paint.Style.STROKE);

        center_x = width / 2;
        center_y = height / 2;

        oval.set(center_x - radius,
            center_y - radius,
            center_x + radius,
            center_y + radius);
        canvas.drawArc(oval, 90, 180, false, paint);
    }
}

2-在您的 Activity 或 fragment 中初始化此类:-

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new MyView(this));
}