Created attachment 4068 [details] [review]
patch to implement a svg-print backend

FYI - this patch also corrects a small buglet - s/cairo_format_t/cairo_content_t

Created attachment 4289 [details] [review]
Updated patch

Reassign to Emmanuel

Hi Dom,

I would be happy to add multi-page capability to SVG backend, but unfortunately,
it seems inkscape currently doesn't support SVG-Print, and I really want to be
able to open SVG files produced by cairo with it.

An idea would be to stick to current output, and switch to SVG-Print as soon as
document has more than one page.

Hi Emmanuel,

That sounds reasonable. I'll modify my patch to do this.

Created attachment 4501 [details] [review]
Only emits <pageSet> if there is more than one page

This should hopefully be more to your liking.

Hi Dom,

Your patch breaks compositing of svg surfaces.

+    surface->xml_node = xmlNewChild (surface->document->xml_node_main,
+				     NULL, CC2XML ("g"), NULL);

When you had before:

-    surface->xml_node = xmlNewChild (surface->id == 0 ? 
-				     document->xml_node_main : 
-				     document->xml_node_defs, 
-				     NULL, CC2XML ("g"), NULL);

And in one page svg, there's a useless <g> </g> around main surface.

Otherwise, it's ok to commit.

Created attachment 4504 [details] [review]
New patch - should fix compositing

The extra "g" around the content is a harmless artifact. I needed a node to put
the whole page's content into before adding it to the <page> or <svg>, as
appropriate.

This patch should fix compositing of SVG surfaces. The new ID scheme for
surfaces is "surface" + surface->id + "-" + number_of_pages. This way, we keep
the surface0 == primary surface distinction, plus generate unique ids for each
individual page.

If you change naming convention here:

+    snprintf (buffer, sizeof buffer, "surface%d-%d", surface->id, 
+	      _cairo_array_num_elements (&surface->document->pages));

You also need to adapt this code:

    child = xmlNewChild (node, NULL, CC2XML("use"), NULL);
    snprintf (buffer, sizeof buffer, "#surface%d", surface->id);
    xmlSetProp (child, CC2XML ("xlink:href"), C2XML (buffer));

in emit_composite_svg_pattern()

Not that creating a similar svg surface with cairo_surface_create_similar during
drawing of one page, and painting it on an another page may happen, so you need
to store the second id.

Created attachment 7761 [details] [review]
An new patch

Pushed to master.