Products.WatermarkImage Zope 2 Image with thumbnail and watermarking support ========================= Products.WatermarkImage ========================= .. contents:: This package provides a Zope 2 Image content type with thumbnail and watermarking support. It aims to be fully API-compatible with the standard Zope Image type. Data storage ============ WatermarkImage instances take the original image data, store it on the instance, and generate a watermarked image as well as a thumbnail, which are stored on the instance as well. The watermarked image is stored as the main image, so all normal image access will return the watermarked image. The thumbnail is a scaled-down copy of the watermarked image. Thumbnail support ================= Whenever a WatermarkImage is created or updated, a thumbnail is generated as well. Thumbnail data can be viewed using the ZMI (Zope Management Interface) on the `Thumbnail` tab. Its data can be accessed by adding `/thumbnail.jpg` to the WatermarkImage URL. A new method `tag_thumbnail` can be used to generate a HTML `img` tag for the thumbnail image, its arguments are the same as the standard Zope Image's `tag` method. The following WatermarkImage properties affect thumbnail generation: - Maximum thumbnail height (pixels): The maximum height for the generated thumbnail. Thumbnails retain the original image's height/width ratio, so the actual thumbnail height may be less than the maximum height specified here. - Maximum thumbnail width (pixels): The maximum width for the generated thumbnail. Thumbnails retain the original image's height/width ratio, so the actual thumbnail width may be less than the maximum width specified here. If you change any of these properties through the ZMI `Properties` tab, the thumbnail will be regenerated automatically to reflect the new values. Watermarking support ==================== If the user specifies that a watermarked image should be created, any image upload to the WatermarkImage instance as well as property updates on the ZMI `Properties` tab will generate a watermarked copy of the original image. The original image data can be viewed using the ZMI on the `Edit Original` tab. Its data can be accessed by adding `/original` to the WatermarkImage URL. A new method `tag_original` can be used to generate a HTML `img` tag for the original image, its arguments are the same as the OFS.Image's `tag` method. Access to the original image is protected by a new Zope Permission named `WatermarkImage: View original`. This permission is only granted to the Zope `Manager` role by default. You can use the ZMI `Security` tab to change this default setting. The following WatermarkImage properties affect the watermarking support: - Watermark ID: The Zope Id of a standard Zope Image instance containing the actual watermark to be placed onto the image. - Watermark opacity: The opacity value determines how opaque the watermark will appear on the watermarked image. Its value must be betwen 0 and 1. Opacity 0 will create a transparent watermark, while opacity 1 will apply the watermark image without any transparency manipulation. - Watermark use: Select whether to create no watermark at all (`none`), position a single watermark in a specific place on the image (`position`), tile as many copies of the watermark image onto the image as possible (`tile`), or place a single watermark onto the image, scaled to the original image size (`scale`). - Watermark position on X-axis: Only applicable if `position` has been selected under `Watermark use`. The watermark's top left corner will be placed further to the right by the number of pixels set here. If you specify a negative value, placement will be determined by subtracting the provided value from the original image's width in order to allow right-aligned positioning. - Watermark position on Y-axis: Only applicable if `position` has been selected under `Watermark use`. The watermark's top left corner will be placed lower by the number of pixels set here. If you specify a negative value, placement will be determined by subtracting the provided value from the original image's height in order to allow bottom-aligned positioning. If you change any of these properties through the ZMI `properties` tab, the watermarked image and the thumbnail will be regenerated automatically to reflect the new values. Changing configuration defaults =============================== A user can configure several settings on a per-instance basis which influence thumbnail and watermarked image generation. However, doing so for every WatermarkImage instance is tedious. Instead, a set of configuration defaults can be defined in your Zope instance's `zope.conf` configuration file. Simply add a stanza named `product-config watermarkimage` and define new defaults:: <product-config watermarkimage> watermark_use position watermark_position_x 100 watermark_position_y -100 thumbmail_max_height 100 thumbnail_max_width 100 </product-config> The following keys and their corresponding setting on the ZMI `Properties` tab are recognized: - watermark_use: corresponds to `Watermark use` - watermark_position_x: corresponds to `Watermark position on X axis` - watermark_position_y: corresponds to `Watermark position on Y axis` - watermark_opacity: corresponds to `Watermark opacity` - watermark_id: corresponds to `Watermark ID` - thumbnail_max_height: corresponds to `Maximum thumbnail height (pixels)` - thumbnail_max_width: corresponds to `Maximum thumbnail width (pixels)` Please note: When you set a default in `zope.conf`, it will be applied to the WatermarkImage instance at creation time. Subsequent changes in the `zope.conf` default values will not influence existing instances. Bug tracker =========== If you have suggestions, bug reports or requests please use the issue tracker at http://www.dataflake.org/tracker/ SVN version =========== You can retrieve the latest code from Subversion using setuptools or zc.buildout via this URL: http://svn.dataflake.org/svn/Products.WatermarkImage/trunk#egg=Products.WatermarkImage ------------------------------------------------------------ Changelog ========= 1.0 (2009-05-09) ---------------- Initial release. ------------------------------------------------------------ Download ======== Jens Vagelpohl 0dba4db5a4c2100699b6de8591820716fb57cd46 1.0