fc_native_image_resize

A Flutter plugin that resizes images using native APIs and saves the result to a file or returns encoded image bytes.

	iOS	Android	macOS	Windows 11
Path	✅	✅	✅	✅
URI	✅	✅	✅	-

Android requires API 28 (Android 9) or later. Windows support targets Windows 11.

Image Formats

• Input: JPEG, PNG, and other formats supported by the operating system, such as HEIF/AVIF on supported iOS and macOS versions. Windows input formats depend on the available Windows Imaging Component (WIC) codecs.
• Output: JPEG and lossless PNG.

Usage

Save to a File

import 'package:fc_native_image_resize/fc_native_image_resize.dart';

final plugin = FcNativeImageResize();

await plugin.resizeFile(
  srcFile: srcFile,
  destFile: destFile,
  width: 300,
  height: 300,
  keepAspectRatio: true,
  format: 'jpeg',
  quality: 90,
);

Return Encoded Bytes

Use resizeFileToBytes when you do not need a destination file:

final bytes = await plugin.resizeFileToBytes(
  srcFile: srcFile,
  width: 300,
  height: 300,
  keepAspectRatio: true,
  format: 'jpeg',
  quality: 90,
);

The result is a Uint8List containing a complete encoded image, not raw pixels. It can be displayed with Image.memory(bytes) or uploaded directly.

Both methods share the same native decoding, orientation correction, resizing, and encoding pipeline. resizeFile writes the result to destFile, overwriting an existing file. resizeFileToBytes returns the result without creating a file.

Options

Option	Meaning
srcFile	The source image's local file path, or a URI when srcFileUri is true.
srcFileUri	Defaults to false. URI input is supported on Android, iOS, and macOS, but not Windows.
destFile	The local destination path. Only required by resizeFile.
width, height	Output dimensions or maximum bounds, in pixels, as described below.
keepAspectRatio	Preserves the aspect ratio without upscaling when true; stretches to the exact dimensions when false.
format	'png' or 'jpeg'. Determines the encoding independently of the destination file extension.
quality	JPEG quality from 1 to 100, where 100 is the highest quality. Defaults to 90. Ignored for PNG, but a supplied value must still be valid.

With keepAspectRatio: true, width and height are maximum bounds, not necessarily the final dimensions. For example, an 800 × 400 image resized within 300 × 300 bounds becomes 300 × 150. Either dimension may be -1 to calculate it from the other dimension; both cannot be -1. Images are never upscaled in this mode, and each calculated dimension is at least one pixel.

With keepAspectRatio: false, both dimensions must be positive. The output matches the requested size exactly, even if that requires stretching or upscaling.

Errors

• ArgumentError: invalid dimensions, output format, or quality. Validation happens before the native platform is called.
• FailedToDecodeImageFileException: the source image cannot be opened or decoded.
• PlatformException: another native operation fails, such as encoding the image or writing the destination file.