ImageCompressor

A lightweight Android utility for efficiently compressing images while preserving quality. Implemented as a Kotlin singleton object, ImageCompressor handles resizing, sampling, EXIF-based rotation, and dynamic quality selection based on file size.

🚀 Usage

Call compress from a coroutine scope (e.g., lifecycleScope) since it is a suspend function performing IO operations:

import com.example.utils.ImageCompressor

lifecycleScope.launch {
    val uriString: String = /* the URI string of the image to compress */
    val compressedPath: String? = ImageCompressor.compress(
        context = requireContext(),
        uriString = uriString
    )

    if (compressedPath != null) {
        // The absolute path of the compressed JPEG file
        println("Compressed image saved at: $compressedPath")
    } else {
        // Compression failed
        Toast.makeText(requireContext(), "Image compression failed", Toast.LENGTH_SHORT).show()
    }
}

Note: compress runs on the IO dispatcher. Always call it within a coroutine.

✨ Features

• Dimension Scaling: Resizes images to fit within 1920×1080 while preserving aspect ratio.
• Sampling Optimization: Calculates an optimal inSampleSize to reduce memory usage.
• High-Quality Scaling: Uses Canvas and Matrix for smooth bitmap scaling.
• EXIF Rotation: Reads EXIF orientation data to rotate images correctly.
• Dynamic Quality Selection: Adjusts JPEG compression quality based on the original file size.
• Automatic Naming: Generates unique filenames using timestamps and random suffixes.
• Simple API: Single compress method for easy integration.

⚙️ Dynamic Quality via chooseQuality

The chooseQuality function selects a JPEG quality level based on the input file size:

File Size	JPEG Quality
> 10 MB	30
> 5 MB	40
2–5 MB	50
1–2 MB	60
0.5–1 MB	70
0.25–0.5 MB	80
≤ 0.25 MB	90

You can modify chooseQuality to suit your project's requirements by changing size thresholds or quality values:

private fun chooseQuality(context: Context, uri: Uri): Int {
    val size = queryFileSize(context, uri)
    return when {
        size > 10_000_000 -> 30  // Lower quality for files > 10 MB
        size > 5_000_000  -> 40
        size > 2_000_000  -> 55  // Adjust threshold or quality here
        else              -> 85  // Higher base quality for small files
    }
}

Contributions and pull requests are welcome! 🌟