- Signed URLs
- Srcset Generation
- Running Tests
The library itself has no external dependencies. Although if you want to build from source (or run tests) then you need
ant and the
To add Imgix-Java to your project, include the following in your project's build.gradle:
And if this is your first external MavenCentral dependency you'll need to add, again to your project level build.gradle, the following:
To create a jar from source:
Once a new version has been merged into main on GitHub (don't forget to update the version numbers in build.gradle first!), it can be deployed to Bintray with
gradle build && gradle bintrayUpload. After that, the new version can be viewed via the Bintray web interface.
To begin creating imgix URLs, add the jar to your project's classpath and import the imgix library. The URL builder can be reused to create URLs for any images on the domains it is provided.
HTTPS support is available by default. However, if you need HTTP support, call setUseHttps on the builder:
To produce a signed URL, you must enable secure URLs on your source and then provide your signature key to the URL builder.
The imgix-java library allows for generation of custom
srcset attributes, which can be invoked through
createSrcSet(). By default, the
srcset generated will allow for responsive size switching by building a list of image-width mappings.
The above will produce the following srcset attribute value which can then be served to the client:
In cases where enough information is provided about an image's dimensions,
createSrcSet() will instead build a
srcset that will allow for an image to be served at different resolutions. The parameters taken into consideration when determining if an image is fixed-width are
w (width) and
createSrcSet() with either a width or height provided, a different
srcset will be generated for a fixed-size image instead.
Will produce the following attribute value:
For more information to better understand
srcset, we recommend Eric Portis' "Srcset and sizes" article which goes into depth about the subject.
This library will automatically append a variable
q parameter mapped to each
dpr parameter when generating a fixed-width image srcset. This technique is commonly used to compensate for the increased file size of high-DPR images.
Since high-DPR images are displayed at a higher pixel density on devices, image quality can be lowered to reduce overall file size without sacrificing perceived visual quality. For more information and examples of this technique in action, see this blog post.
This behavior will respect any overriding
q value passed in as a parameter. Additionally, it can be disabled altogether by passing
disableVariableQuality = true to
This behavior specifically occurs when a fixed-width image is rendered, for example:
The above will generate a srcset with the following
In situations where specific widths are desired when generating
srcset pairs, a user can specify them by passing an array of positive integers as
Note: in situations where a
srcset is being rendered as a fixed image, any custom
widths passed in will be ignored.
Additionally, if both
widths and a width
tolerance are passed to the
createSrcSet method, the custom widths list will take precedence.
In certain circumstances, you may want to limit the minimum or maximum value of the non-fixed (fluid-width)
srcset generated by the
createSrcSet method. To do this, you can specify the widths at which a srcset should
Formatted version of the above srcset attribute:
tolerance dictates the maximum
tolerated difference between an image's downloaded size and its rendered size.
For example, setting this value to 0.1 means that an image will not render more than 10% larger or smaller than its native size. In practice, the image URLs generated for a width-based srcset attribute will grow by twice this rate.
A lower tolerance means images will render closer to their native size (thereby increasing perceived image quality), but a large srcset list will be generated and consequently users may experience lower rates of cache-hit for pre-rendered images on your site.
By default, srcset width
tolerance is set to
0.08 (8 percent), which we consider to be the ideal rate for maximizing cache hits without sacrificing visual quality. Users can specify their own width tolerance by providing a positive scalar value as width
In this case, the width
tolerance is set to 20 percent, which will be reflected in the difference between subsequent widths in a srcset pair:
To run tests clone this project and run:
Dependencies for running tests (junit, etc) are provided (in
test/lib and referenced in the build config).
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