如何在圆周上绘制渐变笔画？

Question

如何围绕圆圈绘制渐变笔划？ 我试过像

// inside init called only once
            mGlowMenuPaint.setStyle(Style.STROKE);
            mGlowMenuPaint.setColor(Color.TRANSPARENT);
            mGlowMenuPaint.setStrokeWidth(15);
            Shader s = new SweepGradient(0, 0, Color.BLACK, Color.WHITE);
            mGlowMenuPaint.setShader(s);


// inside onDraw method
            canvas.drawArc(mMenuRect, mStartAngle, 360, true, mGlowMenuPaint);

但它不是渐变。有谁知道什么是问题？

Answer 1

您可以尝试这样的事情：

<<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
    <shape
        android:innerRadius="80dp"
        android:shape="ring"
        android:thickness="20dp"
        android:useLevel="false">
        <size
            android:width="200dp"
            android:height="200dp" />
        <gradient
            android:endColor="#00ff0000"
            android:gradientRadius="200"
            android:startColor="#ffff0000"
            android:type="radial" />
    </shape>
</item>
<item
    android:bottom="20dp"
    android:left="20dp"
    android:right="20dp"
    android:top="20dp">
    <shape android:shape="oval">
        <stroke
            android:width="1dp"
            android:color="#ff0000" />
    </shape>
</item>
</layer-list>