转角半径不适用于进度圆

Question

我正在尝试让我的进度圆具有圆角边缘，但似乎角半径属性没有做任何事情。

What I have

What I want

content_main.xml：

    <ProgressBar
    android:id="@+id/circularProgressbar"
    style="?android:attr/progressBarStyleHorizontal"
    android:layout_width="250dp"
    android:layout_height="250dp"
    android:layout_marginTop="16dp"
    android:indeterminate="false"
    android:max="500"
    android:onClick="reverseCount"
    android:progress="0"
    android:progressDrawable="@drawable/circular_progress"
    android:secondaryProgress="500"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

circular_progress.xml drawable：

             

        <solid
            android:color="@color/progressBackground"/>
    </shape>
</item>
<item android:id="@android:id/secondaryProgress">
    <shape
        android:innerRadiusRatio="3"
        android:shape="ring"
        android:thicknessRatio="14.0"
        android:useLevel="true">
        <gradient
            android:centerColor="@color/progressSecondary"
            android:endColor="@color/progressSecondary"
            android:startColor="@color/progressSecondary"
            android:type="sweep" />
    </shape>
</item>
<item android:id="@android:id/progress">
    <rotate
        android:fromDegrees="270"
        android:pivotX="50%"
        android:pivotY="50%"
        android:toDegrees="270">
        <shape
            android:innerRadiusRatio="3"
            android:shape="ring"
            android:thicknessRatio="14.0"
            android:useLevel="true">
            <rotate
                android:fromDegrees="0"
                android:pivotX="50%"
                android:pivotY="50%"
                android:toDegrees="360" />
            <gradient
                android:centerColor="@color/colorPrimary"
                android:endColor="@color/colorPrimaryDark"
                android:startColor="@color/colorPrimaryDark"
                android:type="sweep" />
            <corners
                android:radius="20dp"
                android:bottomLeftRadius="8dp"
                android:bottomRightRadius="8dp"
                android:topLeftRadius="8dp"
                android:topRightRadius="8dp"/>
        </shape>
    </rotate>
</item>

我非常感谢帮助，因为我已经看了太久了。