Integration of Zoom.it hosted image zoom in plone.
This add-on integrates the zoom.it service into Plone. It includes a Dexterity behavior which can be assigned to content types, and also a marker interface IZoomItImage which can be assigned to individual instances or to content classes (using e.g. implements, classImplements, or the zcml class directive).
Zoom.it is a Microsoft Live Labs provided webservice which generates DeepZoom tiled image representations of hosted images and provides a friendly SeaDragon-based viewer for them. It allows very high resolution images to be viewed in a friendly manner.
The adapter/behavior provided in this package assumes the content it is applied to has an image attribute or a getImage method. The package provides scripts to replace the image in the primary view with the js/silverlight viewer. That script assumes that the primary view of the content includes the primary image in the main content area inside of an anchor (i.e. #content a > img:first-child).
The zoom.it API is called to process the image the first time the content is saved. However, the API call will only be made if the image is publicly visible (because the zoom.it service needs to retrieve it via a public url). If the image has not yet been processed, Image processing will also be initiated after workflow transitions. As a result, image content that was not publicly accessible to the zoom.it service will be automatically processed once it becomes accessible via a workflow transition. This will not cause non-workflowed images in private folders to be processed when the folder is made public. In that case, the image must be resaved or manually processed using the Zoom.it action menu.
Processing of large images may take some time (and may occasionally fail), to handle this the add-on provides an action menu item for viewing and updating the progress of the image processing and manually re-initiating the process after a failure. If the processing has not been completed, editing the content will also update the status information.
Editing the image field will also cause the image to be re-processed.
Microsoft’s Zoom.it service is an unsupported experimental service, with questionable reliability. It is also a one of a kind way to make it easy to display very high resolution images with minimal effort via a convenient API. Images which have already been processed seem to be reliably available from the service; however, there appear to be extended periods where the service will not accept new images. As a result, initial processing may fail. For that reason this add-on is designed as a progressive enhancement, and will only display the viewer when the processed image is available.
See the FAQ.
Because Zoom.it requires a publicly accessible URL to retrieve the image, this add-on will not work on private content or when edited from non-internet accessible urls. The adapter intentionally skips requests originating from loopback addresses, but a placeholder image can be used for testing from a local address by setting the variable collective.zoomit.config.DEBUG to True.
- Alec Mitchell
- Initial release
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