SimformSolutionsPvtLtd · rashi-simform · May 2, 2025
diff --git a/README.md b/README.md
@@ -64,6 +64,7 @@ Future<Uint8List> compressImage(Uint8List imageData) async {
     quality: 60,
     targetWidth: 400,
     imageQuality: ImageQuality.low,
+    imageFormat: ImageFormat.jpeg, 
   );
   return compressedImage;
 }
@@ -76,6 +77,7 @@ Future<List<Uint8List>> compressMultipleImages(List<Uint8List> imageList) async
     targetWidth: 800,
     batchSize: 3,
     imageQuality: ImageQuality.low,
+    imageFormat: ImageFormat.jpeg,
   );
   return result;
 }
@@ -88,21 +90,13 @@ Future<void> _cancelCompression() async {
 ```
 ## Parameters of `compressImage` function:
 
-| Parameter Name | Data type    | Default Value       | Description                                         |
-|----------------|--------------|---------------------|-----------------------------------------------------|
-| imageData      | Uint8List    | -                   | The image to be compressed                          |
-| quality        | int          | 60                  | The compression quality percentage                  |
-| targetWidth    | int?         | null                | The desired width for the compressed image          |
-| imageQuality   | ImageQuality | ImageQuality.medium | The quality of the image to store after compression |
-
-## Parameters of `compressImage` function:
-
 | Parameter Name | Data type    | Default Value       | Description                                               |
 |----------------|--------------|---------------------|-----------------------------------------------------------|
 | imageData      | Uint8List    | -                   | The image to be compressed                                |
 | quality        | int          | 60                  | The compression quality percentage                        |
 | targetWidth    | int?         | null                | The desired width for the compressed image                |
 | imageQuality   | ImageQuality | ImageQuality.medium | The quality of the image to store after compression       |
+| imageFormat    | ImageFormat  | ImageFormat.jpeg    | The format of the output image (jpeg or png)              |
 | batchSize      | int          | 3                   | The number of images to process simultaneously in a batch |
 
 ## About params
@@ -113,6 +107,7 @@ The `targetWidth` parameter allows you to resize the images to a specific width.
 
 Use this parameter when you need all images to have a uniform width. It is particularly useful for optimizing image processing performance.
 Recommended to use this parameter when image size or image width is large.
+
 ### batchSize
 
 The `batchSize` parameter determines how many images are processed in a single batch.
@@ -125,13 +120,26 @@ To dynamically adjust batchSize based on the number of CPU threads available on
 final maxAvailableCPUThreads = Platform.numberOfProcessors;
 final batchSize = maxAvailableCPUThreads > 0 ? maxAvailableCPUThreads ~/ 2 : 1;
 ```
+
+### quality
+
+Specifies the quality of the target image.
+
+Note: On iOS, quality is ignored for PNG because it's a lossless format with no adjustable compression.
+
 ### imageQuality
 
 The `imageQuality` parameter controls the quality of the processed images. It has three predefined values:
 - low
 - medium (default)
 - high
 
+### imageFormat
+
+The `imageFormat` parameter determines the output format of the compressed image:
+- `ImageFormat.jpeg` (default): Creates JPEG images with lossy compression. Better for photos and images without transparency.
+- `ImageFormat.png`: Creates PNG images with lossless compression. Preserves transparency but may result in larger file sizes.
+
 ## Android
 
 You may need to update Kotlin to version `1.5.20` or higher.

diff --git a/android/src/main/kotlin/com/example/fast_image_compress/Constants.kt b/android/src/main/kotlin/com/example/fast_image_compress/Constants.kt
@@ -6,7 +6,10 @@ object Constants {
     const val TARGET_WIDTH: String = "targetWidth"
     const val COMPRESSION_QUALITY: String = "compressionQuality"
     const val IMAGE_QUALITY: String = "imageQuality"
+    const val IMAGE_FORMAT: String = "imageFormat"
     const val IMAGE_QUALITY_HIGH: String = "high"
     const val IMAGE_QUALITY_LOW: String = "low"
     const val IMAGE_QUALITY_MEDIUM: String = "medium"
+    const val FORMAT_JPEG: String = "jpeg"
+    const val FORMAT_PNG: String = "png"
 }
diff --git a/android/src/main/kotlin/com/example/fast_image_compress/FastImageCompressPlugin.kt b/android/src/main/kotlin/com/example/fast_image_compress/FastImageCompressPlugin.kt
@@ -68,6 +68,8 @@ class FastImageCompressPlugin: FlutterPlugin, MethodCallHandler {
       val targetWidth = call.argument<Int?>(Constants.TARGET_WIDTH)
       val compressionQuality = call.argument<Int?>(Constants.COMPRESSION_QUALITY)
       val imageQualityInString = call.argument<String>(Constants.IMAGE_QUALITY)
+      // Get the desired output image format, default to JPEG
+      val imageFormat = call.argument<String>(Constants.IMAGE_FORMAT) ?: Constants.FORMAT_JPEG
 
       // Determine the image quality based on the input string
       val imageQuality =
@@ -117,7 +119,7 @@ class FastImageCompressPlugin: FlutterPlugin, MethodCallHandler {
           val resizedBitmap = resizeBitmap(correctedBitmap, targetWidth)
 
           // Compress the image and convert it to a byte array
-          val compressedBytes = bitmapToByteArray(resizedBitmap, compressionQuality)
+          val compressedBytes = bitmapToByteArray(resizedBitmap, compressionQuality, imageFormat)
           if (compressedBytes == null) {
             // Return the original image if compression fails or when compressed image
             // is larger than original image
@@ -183,26 +185,35 @@ class FastImageCompressPlugin: FlutterPlugin, MethodCallHandler {
   }
 
   // Compress a Bitmap into a byte array
-  private fun bitmapToByteArray(bitmap: Bitmap, compressionQuality: Int? = 80): ByteArray? {
+  private fun bitmapToByteArray(bitmap: Bitmap, compressionQuality: Int? = 80, imageFormat: String = Constants.FORMAT_JPEG): ByteArray? {
     val quality = compressionQuality ?: 80
     val stream = ByteArrayOutputStream()
-    bitmap.compress(Bitmap.CompressFormat.JPEG, quality, stream)
+
+    // Select compression format based on imageFormat parameter
+    val compressFormat = if (imageFormat == Constants.FORMAT_PNG) {
+      Bitmap.CompressFormat.PNG
+    } else {
+      Bitmap.CompressFormat.JPEG
+    }
+
+    bitmap.compress(compressFormat, quality, stream)
     var outputImageSize = stream.toByteArray().size
 
     //  To avoid increasing the size of an already compressed image, compare
     //  input and output sizes, and use lower compression quality if needed.
     if (outputImageSize > inputImageSize) {
-        var updatedCompQuality = quality;
-        while (outputImageSize > inputImageSize && updatedCompQuality >= 10) {
-          bitmap.compress(Bitmap.CompressFormat.JPEG, updatedCompQuality, stream)
-          updatedCompQuality = updatedCompQuality - 10;
-          outputImageSize = stream.toByteArray().size;
-        }
-        if (updatedCompQuality >= 10) {
-          return stream.toByteArray()
-        } else {
-          return null
-        }
+      var updatedCompQuality = quality
+      while (outputImageSize > inputImageSize && updatedCompQuality >= 10) {
+        stream.reset() // Clear the stream
+        bitmap.compress(Bitmap.CompressFormat.JPEG, updatedCompQuality, stream)
+        updatedCompQuality -= 10
+        outputImageSize = stream.toByteArray().size
+      }
+      if (updatedCompQuality >= 10) {
+        return stream.toByteArray()
+      } else {
+        return null
+      }
     }
     return stream.toByteArray()
   }

diff --git a/ios/Classes/FastImageCompressPlugin.swift b/ios/Classes/FastImageCompressPlugin.swift
@@ -32,9 +32,12 @@ enum Constants{
     static let targetWidth = "targetWidth"
     static let compressionQuality = "compressionQuality"
     static let imageQuality = "imageQuality"
+    static let imageFormat = "imageFormat"
     static let high = "high"
     static let low = "low"
     static let medium = "medium"
+    static let formatJPEG = "jpeg"
+    static let formatPNG = "png"
 }
 
 // Enum to represent image quality levels and their associated downscaling factors
@@ -88,6 +91,8 @@ public class FastImageCompressPlugin: NSObject, FlutterPlugin {
         // Optional arguments for compression quality and target width
         let compressionQuality = args[Constants.compressionQuality] as? Int
         let targetWidth = args[Constants.targetWidth] as? Int
+        // Get the desired output image format, default to JPEG
+        let imageFormat = args[Constants.imageFormat] as? String ?? Constants.formatJPEG
 
         // Determine the image quality based on the provided string
         let imageQuality: ImageQuality = {
@@ -100,7 +105,7 @@ public class FastImageCompressPlugin: NSObject, FlutterPlugin {
 
         isCancelled = false // Reset cancellation flag
         // Start resizing and compressing the image
-        resizeImage(imageData: imageData.data, targetWidth: targetWidth, compressionQuality: compressionQuality, imageQuality: imageQuality, result: result)
+        resizeImage(imageData: imageData.data, targetWidth: targetWidth, compressionQuality: compressionQuality, imageQuality: imageQuality, imageFormat: imageFormat, result: result)
     }
 
     // Handles the cancellation of image compression
@@ -112,7 +117,7 @@ public class FastImageCompressPlugin: NSObject, FlutterPlugin {
     // MARK: - Image Processing
 
     // Resizes the image and compresses it based on the provided parameters
-    private func resizeImage(imageData: Data, targetWidth: Int?, compressionQuality: Int? = 80, imageQuality: ImageQuality, result: FlutterResult) {
+    private func resizeImage(imageData: Data, targetWidth: Int?, compressionQuality: Int? = 80, imageQuality: ImageQuality, imageFormat: String, result: @escaping FlutterResult) {
         // Decode the image data into a UIImage
         guard let image = UIImage(data: imageData) else {
             result(FlutterError(code: "INVALID_IMAGE", message: "Unable to decode image data", details: nil))
@@ -127,7 +132,7 @@ public class FastImageCompressPlugin: NSObject, FlutterPlugin {
         }
 
         // Compress the resized image
-        compressImage(finalImage: finalImage, imageData: imageData, compressionQuality: compressionQuality, result: result)
+        compressImage(finalImage: finalImage, imageData: imageData, compressionQuality: compressionQuality, imageFormat: imageFormat, result: result)
     }
 
     // Resizes the image to the target width and quality
@@ -154,17 +159,23 @@ public class FastImageCompressPlugin: NSObject, FlutterPlugin {
     }
 
     // Compresses the resized image and returns the compressed data
-    private func compressImage(finalImage: UIImage, imageData: Data, compressionQuality: Int?, result: FlutterResult) {
-        var quality = Double(compressionQuality ?? 80) / 100.0 // Default quality is 80%
-        var compressedData = finalImage.jpegData(compressionQuality: quality)
-
+    private func compressImage(finalImage: UIImage, imageData: Data, compressionQuality: Int?, imageFormat: String, result: FlutterResult) {
+        let quality = Double(compressionQuality ?? 60) / 100.0 // Default quality is 80%
         let inputImageSize = imageData.count
-        var outputImageSize = compressedData?.count ?? Int.max
-
-        //  To avoid increasing the size of an already compressed image, compare
-        //  input and output sizes, and use lower compression quality if needed.
-        if outputImageSize > inputImageSize {
-            compressedData = performIterativeCompression(finalImage: finalImage, inputImageSize: inputImageSize, initialQuality: quality)
+        var compressedData: Data?
+
+        // Generate compressed data based on the requested format
+        if imageFormat == Constants.formatPNG {
+            compressedData = finalImage.pngData()
+        } else {
+            // Default to JPEG
+            compressedData = finalImage.jpegData(compressionQuality: quality)
+
+            // For JPEG, we can try iterative compression if the output size is larger than input
+            let outputImageSize = compressedData?.count ?? Int.max
+            if outputImageSize > inputImageSize {
+                compressedData = performIterativeCompression(finalImage: finalImage, inputImageSize: inputImageSize, initialQuality: quality)
+            }
         }
 
         // Return the compressed data or an error if compression failed

diff --git a/lib/src/fast_image_compress.dart b/lib/src/fast_image_compress.dart
@@ -53,12 +53,14 @@ class FastImageCompress {
   /// data or `null` if the compression is cancelled.
   ///
   /// - [imageData]: The image data as a `Uint8List` to be compressed.
-  /// - [quality]: The compression quality percentage (default is 80).
+  /// - [quality]: The compression quality percentage (default is 60).
   ///   Must be a value between 0 and 100, where 100 represents the highest quality.
   /// - [targetWidth]: The desired width for the compressed image (default is 500).
   ///   The height will be scaled proportionally to maintain the aspect ratio.
   /// - [imageQuality]: The quality of the image to undergo compression. This can be
   ///   `ImageQuality.high`, `ImageQuality.medium`, or `ImageQuality.low` (default is `ImageQuality.medium`).
+  /// - [imageFormat]: The format of the output image. This can be `ImageFormat.jpeg` (default)
+  ///   or `ImageFormat.png`. PNG format preserves transparency but may result in larger file sizes.
   ///
   /// ### Returns:
   /// A `Future<Uint8List?>` that resolves to the compressed image data as a `Uint8List`,
@@ -77,6 +79,7 @@ class FastImageCompress {
     int quality = 60,
     int? targetWidth = 500,
     ImageQuality imageQuality = ImageQuality.medium,
+    ImageFormat imageFormat = ImageFormat.jpeg,
   }) {
     assert(
       quality > 0 || quality < 100,
@@ -95,6 +98,7 @@ class FastImageCompress {
       quality,
       targetWidth,
       imageQuality,
+      imageFormat,
     );
   }
 
@@ -105,14 +109,16 @@ class FastImageCompress {
   /// processed in parallel batches to optimize performance.
   ///
   /// - [images]: A list of `Uint8List` objects representing the images to be compressed.
-  /// - [quality]: The compression quality percentage (default is 80).
+  /// - [quality]: The compression quality percentage (default is 60).
   ///   Must be a value between 0 and 100, where 100 represents the highest quality.
   /// - [targetWidth]: The desired width for the compressed images (default is 500).
   ///   The height will be scaled proportionally to maintain the aspect ratio.
   /// - [batchSize]: The number of images to process simultaneously in a batch (default is 3).
   ///   Must be at least 1.
   /// - [imageQuality]: The quality of the image to undergo compression. This can be
   ///   `ImageQuality.high`, `ImageQuality.medium`, or `ImageQuality.low` (default is `ImageQuality.medium`).
+  /// - [imageFormat]: The format of the output image. This can be `ImageFormat.jpeg` (default)
+  ///   or `ImageFormat.png`. PNG format preserves transparency but may result in larger file sizes.
   ///
   /// ### Returns:
   /// A `Future` that resolves to a `List<Uint8List>` containing the compressed images.
@@ -133,6 +139,7 @@ class FastImageCompress {
     int? targetWidth,
     int batchSize = 3,
     ImageQuality imageQuality = ImageQuality.medium,
+    ImageFormat imageFormat = ImageFormat.jpeg,
   }) async {
     assert(
       quality > 0 || quality < 100,
@@ -155,6 +162,7 @@ class FastImageCompress {
           quality,
           targetWidth,
           imageQuality,
+          imageFormat,
         );
         if (compressedImage != null) {
           compressedImages.add(compressedImage);

diff --git a/lib/src/image_compression_service.dart b/lib/src/image_compression_service.dart
@@ -46,15 +46,16 @@ class ImageCompressionService {
     int quality,
     int? targetWidth,
     ImageQuality imageQuality,
-  ) async {
+      [ImageFormat imageFormat = ImageFormat.jpeg]) async {
     if (!isInitialized) await initializeIsolate();
     final responsePort = ReceivePort();
     _isolateSendPort!.send({
       Constants.imageData: imageData,
       Constants.quality: quality,
       Constants.targetWidth: targetWidth,
       Constants.port: responsePort.sendPort,
-      Constants.imageQuality: imageQuality
+      Constants.imageQuality: imageQuality,
+      Constants.imageFormat: imageFormat.name,
     });
     return await responsePort.first as Uint8List?;
   }
@@ -75,13 +76,16 @@ class ImageCompressionService {
           final targetWidth = message[Constants.targetWidth] as int?;
           final responsePort = message[Constants.port] as SendPort;
           final imageQuality = message[Constants.imageQuality] as ImageQuality;
+          final imageFormat = message[Constants.imageFormat] as String? ??
+              ImageFormat.jpeg.name;
 
           Uint8List? processedImage;
           processedImage = await imageCompress(
             imageData,
             targetWidth,
             quality,
             imageQuality.name,
+            imageFormat,
           );
 
           responsePort.send(processedImage);
@@ -97,13 +101,15 @@ class ImageCompressionService {
     int? targetWidth,
     int compressionQuality,
     String imageQuality,
+    String imageFormat,
   ) async {
     try {
       final message = {
         Constants.imageData: imageData,
         Constants.targetWidth: targetWidth,
         Constants.compressionQuality: compressionQuality,
         Constants.imageQuality: imageQuality,
+        Constants.imageFormat: imageFormat,
       };
       final resizedImage = await platform.invokeMethod<Uint8List?>(
         Constants.compressImageMethodName,
@@ -130,3 +136,12 @@ enum ImageQuality {
   medium,
   high;
 }
+
+/// Specifies the format of the compressed image output
+enum ImageFormat {
+  /// JPEG format (default) - supports lossy compression with quality settings
+  jpeg,
+
+  /// PNG format - lossless compression that preserves transparency
+  png;
+}
diff --git a/lib/values/constants.dart b/lib/values/constants.dart
@@ -31,5 +31,6 @@ class Constants {
   static const String compressionQuality = 'compressionQuality';
   static const String targetWidth = 'targetWidth';
   static const String imageQuality = 'imageQuality';
+  static const String imageFormat = 'imageFormat';
   static const String port = 'port';
 }