Android Jpeg Encoder for Titanium

Description

By default, Titanium encodes jpeg image with the highest quality possible, sometimes resulting in heavy files sent through the network. JpegEncoder provides a small set of functions to scale, crop and compress an image.

Jpeg Encoder only works on Android platforms. If you need another module which offers similar features on iOS device, take a look at gudmundurh's Titanium Imaging.

This module is still in beta, feel free to report any issues. Or fork it, patch the issue and send a pull request.

Install the module

You can either download a precompiled build from Github (downloads button, if so skip steps one and two) or get the source code and build it yourself.

At root, run ant build.xml
Get the generated zip file from the dist/ directory
Copy the downloaded (or generated) archive to the root of the Titanium app, or to the root of the system Titanium installation.
Edit tiapp.xml to add the module

<modules>
    <module version="{VERSION_NUMBER}" platform="android">com.novelys.jpegencoder</module>
</modules>

Accessing the Jpeg Encoder Module

To access this module from JavaScript, you would do the following:

var JpegEncoder = require("com.novelys.jpegencoder");

The JpegEncoder variable is a reference to the Module object.

Usage

You need to pass a blob image to the encoder, set the imageBlob property with the given blob.

Compressing

You can choose the compression level by setting the compressionQuality property, then call the encode method. Supported values range from 1 (lowest quality) to 100 (highest quality). If compressionQuality is left blank, 70 will be used as default. The minimal example would be:

var first = JpegEncoder.createEncoder({
	imageBlob: imageBlob,
	compressionQuality: 70
});

first.encode();

var newImageBlob = first.imageBlob;

Scaling

Scaling an image is just as easy. Set the newHeight and newWidth properties and call the scaleAndEncode method.

var second = JpegEncoder.createEncoder({
	imageBlob: imageBlob,
	newWidth: 500,
	newHeight: 300,
});

second.scaleAndEncode();

Alternatively, if you want to keep proportions during scaling you can set only one property (either newHeight or newWidth) and set the keepProportions property to true.

var third = JpegEncoder.createEncoder({
	imageBlob: imageBlob,
	keepProportions: true,
	newHeight: 500,
});

third.scaleAndEncode();

Cropping

To crop a picture, you need to pass a dictionary to the cropRect property, which contains the coordinates of the top left corner of the crop rectangle, its width and its height. And then call cropAndEncode.

var fourth = JpegEncoder.createEncoder({
	imageBlob: imageBlob,
	cropRect: {x: 30, y: 30, width: 100, height: 100}
});

fourth.cropAndEncode();

You can as well scale and crop at the same time. The module will first scale the image and then crop the result upon the given rectangle.

var fifth = JpegEncoder.createEncoder({
	imageBlob: imageBlob,
	compressionQuality: 70,
	newWidth: 500,
	newHeight: 300,
	cropRect: {x: 30, y: 30, width: 100, height: 100}
});

fifth.scaleCropAndEncode();

Retrieving encoded image

To retrieve encoded image, simply calls the imageBlob property from the encoder. It will still be a blob image you can work with. For instance:

var scaled = Titanium.Filesystem.getFile('scaled_and_compressed2.jpg');
scaled.write(second.imageBlob);

Check example/app.js for more examples.

Authors

Android Jpeg Encoder was made by Frédéric Maquin from Novelys (http://www.novelys.com). A small and agile software development team.

Feel free to contact us through our website (http://www.novelys.com/contact)

License

Licensed under the terms of the Apache Public License.

Please see the LICENSE included with this distribution for details.

pegli/titanium-jpegencoder