long1eu/flutter_native_image

Native Flutter Image tools

flutter_native_image

Native Flutter Image tools

This plugin aims to have native tools to resize images and reduce their quality by compression. The code is somewhat hacky (especially the iOS part), but it works for my needs and hasn't crashed on me. Feel free to improve it if you want to.

Right now there is only a compression function available.

Usage

Install

Add the following lines to your pubspec.yaml under dependencies

flutter_native_image:
  git: https://github.com/btastic/flutter_native_image.git

Compress an image

File compressedFile = await FlutterNativeImage.compressImage(file.path,
    quality: quality, percentage: percentage);

You have to give it a file from the file system and optionally provide a quality (1-100) and a resizing percentage (1-100). Each platform will use it's proper tools to handle the resizing.

To resize the image to the certain size, use following code:

ImageProperties properties = await FlutterNativeImage.getImageProperties(file.path);
File compressedFile = await FlutterNativeImage.compressImage(file.path, quality: 80, 
    targetWidth: 600, targetHeight: 300);

Keep aspect ratio of the file:

ImageProperties properties = await FlutterNativeImage.getImageProperties(file.path);
File compressedFile = await FlutterNativeImage.compressImage(file.path, quality: 80, 
    targetWidth: 600, 
    targetHeight: (properties.height * 600 / properties.width).round());

Get image properties

ImageProperties properties = await FlutterNativeImage.getImageProperties(file.path);

It returns an ImageProperties object containing the width and the height of the image.

Crop an image

File croppedFile = await FlutterNativeImage.cropImage(file.path, originX, originY, width, height);

Returns a file containing the image cropped with the given dimensions.

Contributions

Alexis Leblond (a-leblond) the image properties feature.

Eugene Strokin the resize to target height/width feature

Credits

Shoutouts to Trevor from Vocaro.com. He had the fitting algorithm for resizing images in Objective-C.

Source: http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/

For preserving exif information, I took the code from googles image_picker github (https://github.com/flutter/plugins/tree/master/packages/image_picker)