This is the code for displaying images that have been posted to a group. It provides two major components: a content provider for displaying an image, and the image page.

The content provider groupserver.GroupImage displays an image that has been posted to a group. It takes four arguments:

For example, displaying an image with a maximum size of 100 pixels high and 100 wide:

<span tal:define="fileId view/imageId; width 100; height 100; alt
                  string:The posted image ${view/filename};"
                  tal:replace="structure
                  provider:groupserver.GroupImage">An image</span>

The image is acquired using the virtual file-archive [1]. The image is then re-sized by gs.image [2] in such a way that the original aspect ratio is kept. The content provider will then produce an <img> element. Based on the result of the re-sizing the src attribute will link to one of three things:

1. The original file ({group}/files/f/{fileId}), if no resizing was needed.
2. The re-sized file ({originalFileLink}/resize/{width}/{height}) if resizing is needed and the image is bigger than 1K.
3. A data-URI if the image is smaller than 1K.

The square image content provider also re-sizes, but ensures the image is square.

The square image content provider, groupserver.SquareGroupImage, always produces square images, rather than possibly rectangular images. It takes three arguments:

The image is re-sized (or not) by gs.image [2], and the same rules for linking to the image apply:

• No change: {group}/files/f/{fileId}
• Resized: {originalFileLink}/square/{size}
• Tiny: a data-URI.

The Image page, image in the Messages context, exists because people often post very large images to groups. The Image page re-sizes the image to something that is easier to view on the Web, and share using the Sharebox JavaScript.

The actual image page is gsimage, in the Messages context. The image page performs the traversal of the URL to either parse the file ID out, or display one of the error pages

The Image page makes use of the resource gs-group-messages-image-20130305.js to provide the code for the Share button [3].

There are two error pages, specific to the Image page.

400 (Bad request):

The URL was missing the file identifier, so the gsimage400 page is shown.

410 (Gone):

The identifier for the image could be found, but the associated post is hidden, so the image_hidden.html page is shown.

If the file could not be found then the standard 404 page is shown.

• Code repository: https://github.com/groupserver/gs.group.messages.image
• Questions and comments to http://groupserver.org/groups/development
• Report bugs at https://redmine.iopen.net/projects/groupserver