How to save a JPEG image on Android with a custom quality level

Question

On Android, how do I save an image file as a JPEG at 30% quality?

In standard Java, I would use ImageIO to read the image as a BufferedImage

Answer 1

Using Kotlin to save a file in path to tmpPath:

Files.newInputStream(path).use { inputStream ->
    Files.newOutputStream(tmpPath).use { tmpOutputStream ->
        BitmapFactory
            .decodeStream(inputStream)
            .compress(Bitmap.CompressFormat.JPEG, 30, tmpOutputStream)
    }
}

Edit: make sure you check for the possibility of the decode failing (and returning null) and also that compress actually worked (boolean return type).

    val success: Boolean = Files.newInputStream(path).use { inputStream ->
        Files.newOutputStream(tmpPath).use { tmpOutputStream ->
            BitmapFactory
                .decodeStream(inputStream)
                ?.compress(Bitmap.CompressFormat.JPEG, config.qualityLevel, tmpOutputStream)
                ?: throw Exception("Failed to decode image")
        }
    }

    if (!success) {
        throw Exception("Failed to compress and save image")
    }