GNOME Bugzilla – Bug 620124
allow overriding href resources
Last modified: 2017-12-13 17:40:56 UTC
I want to be able to provide extra xinclude data from memory, instead of from file: or gvfs locations. (I'm going to use this to provide runtime stylesheets etc.) To do this, I need to redirect href resource lookup through the RsvgHandleClass (which I can then derive). Proof-of-concept patch attached.
Created attachment 162344 [details] [review] Allow extending resource lookup Add RsvgHandleClass:acquire-resource vfunc that allows returning a GInputStream to read the data from. Bug #620124.
Very impressive. Do you have some sample codes which uses this new vfunc?
Created attachment 162502 [details] testcase.c This shows how one would use this. E.g. by returning a GMemoryInputStream with the data one wants to inject. The use case for me is that I want to inject style information at runtime without having to write a file with the style info, and to do runtime i18n. I found a bug in my origin patch (there needs to be a |g_byte_array_set_size (data, position);| before |return data;| in _rsvg_handle_acquire_xlink_href_resource. Also I found that having this not just a vfunc but a signal would be good; I'll update my patch tomorrow.
So I've updated the patch (attaching in a minute), but I'm not really satisfied with the setup. I really do like the ability to return a GError so librsvg knows I didn't just not handle the request, but instead there was an error handling the request, and so it should NOT fall back to its default implementation. However GError** in a signal param isn't really good gobject-y design... Also, maybe the signal should just only be emitted for some specific href's like those a with pseudo-scheme like "x-rsvg-resource:" ? Any advice?
Created attachment 162797 [details] [review] Allow extending resource lookup Add RsvgHandleClass:acquire-resource vfunc that allows returning a GInputStream to read the data from. Bug #620124.
I have an idea for this. But it is bit more painful than yours. The idea is: 1. Create a new object represents external resource. The object has set_input_stream or set_loader_func method. 2. Emit a signal with the object. 3. Set input stream by set_input_stream method in the callback of the signal. 4. Use the input stream to obtain external resource data. The code will be like the following: RsvgExternalResource *external; external = rsvg_external_resource_new(uri); signal_emit_by_name(RsvgHandle*, "start-loading-external-resource", external); if (external->user_input_stream) { /* loading data from the stream which is set by user */ } else { /* default loader */ } This way avoids including GError in the signal but user who uses this interfaces have to connect a signal and set an input stream of just connecting a signal. The names of signal, object etc. are not well-considered by the way.
-- GitLab Migration Automatic Message -- This bug has been migrated to GNOME's GitLab instance and has been closed from further activity. You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.gnome.org/GNOME/librsvg/issues/38.