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#1336 Error in processing images with absolute file URL
Hi,
i am working with docbook 5 and stylesheets 1.78.1 bundled within the oxygen xml editor in windows 7. I have an docbooc book which is constructed as a result of some xslt transformation. Within this transformation, i use the unparsed-entity-uri() function to calculate the value of @fileref attributes for images. This xslt transformation is done with the saxon 9.5.1.5 engine. The resulting book is valid with respect to docbook 5 RNG Grammar.
However, when i apply XHTML chunk Transformation, the images are not visible in the generated output.The links to the image file from HTML are broken. For example: @fileref='file:/C:/temp/image.png' in the docbook sources leads to @src='../../file:/C:/temp/image.png' within the img element in HTML.
I think the HTML transformation does not recognize it as an absolute file URI. I am pretty sure that this is caused by calculating the value of the @src attribute of the img element within the process.image template in the graphics.xsl file. If i understand correctly, it is checked whether the given URL contains the string '://'. If this is not the case, it is handled as a relative file URL. This is obviously the case in my example, since there is only one slash after the colon, not two. I tested the same thing after manually adding slashes (file:///C:/temp/image.png) ant everything works fine.
So it turns out that absolute file URIs in the form of 'file:/C:/ ...' are not supported properly. Since this is a valid syntax for absolute file URLs, and since this syntax is generated as a result of the unparsed-entity-uri() function, this seems to be a bug in the stylesheets.
Sincerely,
Frank
The sad truth is that file URI is really underspecified and if you will strictly follow existing standards in the place you will find that file:/c:/... is not valid file URI. However such URIs are generated and consumed by many applications, so it seems reasonable to support this case in the stylesheets.
I checked in a fix for this to support that file:/ syntax for absolute paths in images. The latest snapshot was tested and works.