Android Bitmap裁剪椭圆形

Question

假设我有一个用前置摄像头拍摄的人像位图。 拍照后，如何将位图裁剪为椭圆形叠加层的形状？ 椭圆形位于屏幕的中心。 椭圆形具有固定的高度和宽度

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:tools="http://schemas.android.com/tools"
         android:orientation="vertical"
         android:layout_width="match_parent"
         android:layout_height="match_parent">

<FrameLayout
    android:id="@+id/content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

<!-- camera viewfinder here which fits the whole screen-->
<RelativeLayout
    android:id="@+id/cameraLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:paddingTop="10dp">

        <!--Custom buttons-->

    </RelativeLayout>

    <RelativeLayout
        android:id="@+id/record_panel"
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:background="@android:color/transparent"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

        <!--Capture button-->

    </RelativeLayout>

</RelativeLayout>

<!--the oval-shaped overlay-->
<ImageView 
    android:layout_width="210dp"
    android:layout_height="318dp"
    android:id="@+id/overlay"
    android:layout_gravity="center"
    android:src="@mipmap/oval" />

</FrameLayout>

截图：

Answer 1

您可以根据如何从位图裁剪圆来解决问题：

    @Override
    public Bitmap crop(Bitmap source) {
        int size = Math.min(source.getWidth(), source.getHeight());

        int x = (source.getWidth() - size) / 2;
        int y = (source.getHeight() - size) / 2;

        Bitmap squaredBitmap = Bitmap.createBitmap(source, x, y, size, size);
        if (squaredBitmap != source) {
            source.recycle();
        }

        Bitmap bitmap = Bitmap.createBitmap(size, size, source.getConfig());

        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();
        BitmapShader shader = new BitmapShader(squaredBitmap,
                BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);
        paint.setShader(shader);
        paint.setAntiAlias(true);

        float r = size / 2f;
        canvas.drawCircle(r, r, r, paint);

        squaredBitmap.recycle();
        return bitmap;
    }

现在，只需将canvas.drawCircle更改为canvas.drawOval并为其提供适当的值即可。