为SurfaceView设置效果（圆角、渐变蒙层）

设置SurfaceView圆角

 /**
     * 设置Surfaceviewl圆角
     */
    private void setSurfaceviewCorner(final float radius) {
        mSurfaceView.setOutlineProvider(new ViewOutlineProvider() {
            @Override
            public void getOutline(View view, Outline outline) {
                Rect rect = new Rect();
                view.getGlobalVisibleRect(rect);
                int leftMargin = 0;
                int topMargin = 0;
                Rect selfRect = new Rect(leftMargin, topMargin, rect.right - rect.left - leftMargin, rect.bottom - rect.top - topMargin);
                outline.setRoundRect(selfRect, radius);
            }
        });
        mSurfaceView.setClipToOutline(true);
    }

为SurfaceView设置渐变蒙层，设置foreground属性

    <com.example.myapplication.CustomSurfaceView
        android:id="@+id/sv_test"
        android:layout_width="500dp"
        android:layout_height="500dp"
        android:foreground="@drawable/test_gradient" />

test_gradient.xml为上下往中间的渐变效果代码如下：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <gradient
        android:startColor="#60000000"
        android:centerColor="#20000000"
        android:endColor="#60000000"
        android:angle="90" />

</shape>```