画布裁剪图像 Android

Question

I use canvas to create a circle. Now I want to export that circle to a png file, removing everything other than the circle and taking what is in the circle. Note I have 2 frames on top of each other.

Answer 1

You can do that using Android PorterDuffMode Here is the code

private fun crop(bitmapImage: Bitmap): Bitmap {
    val bitmap = Bitmap.createBitmap(
            bitmapImage.width,
            bitmapImage.height,
            Bitmap.Config.ARGB_8888
    )
    val canvas = Canvas(bitmap)
    val paint = Paint(Paint.ANTI_ALIAS_FLAG)
    canvas.drawCircle(100.0f, 100.0f, 50.0f, paint)
    paint.xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC_OUT)
    canvas.drawBitmap(bitmapImage, 0.0f, 0.0f, paint)
    return bitmap
}

you can change the circle pivot and radius to achieve your result, If you pass the bitmap of the image, it will return the bitmap and you can save to file