bug#64908: 29.1; svg parse failure

[David Ponce <da_vid@orange.fr>]

On 05/08/2023 17:14, Alan Third wrote:
> On Sat, Aug 05, 2023 at 02:32:07PM +0200, David Ponce wrote:
>> On 05/08/2023 11:58, Alan Third wrote:
>> I did test your V2 patch, and it seems to work well.
>> I tend to agree with your reasoning, even if I am not enough a
>> librsvg expert to fully understand all the details.
> 
> Thanks!
> 
>> One case however is not working, when the svg image just specify
>> percentage for width and height without a viewbox, like this:
>>
>> '(image :type svg :data
>>       "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"100%\" height=\"100%\">
>>    <defs id=\"defs3051\">
>>      <style type=\"text/css\" id=\"current-color-scheme\">
>>        .ColorScheme-Text {
>>          color:#232629;
>>        }
>>        </style>
>>    </defs>
>>   <path
>>      style=\"fill:currentColor;fill-opacity:1;stroke:none\"
>>      d=\"m7.707031 3l-.707031.707031 6.125 6.125 1.167969 1.167969-1.167969 1.167969-6.125 6.125.707031.707031 6.125-6.125 1.875-1.875-1.875-1.875-6.125-6.125\"
>>      class=\"ColorScheme-Text\"
>>      />
>> </svg>"
>>       :scale 1)
>>
>> I can display a such image in firefox, gwenview, or inkscape, but not in Emacs.
>> I guess it works in applications that provide a default viewbox when not defined.
>> And it is failing in Emacs because no default viewbox is provided.
> 
> Very strange, it works here. rsvg_handle_get_geometry_for_layer should
> handle this fine. I wonder if something subtle has changed with
> 2.56... I can't fine anything in the documentation to say this has
> changed...
> 
> We can always provide an absolute fallback of 100x100 or something. I
> think that's what we used to do. But it would be good to know if
> something is actually broken here. Are you able to check the return
> value of rsvg_handle_get_geometry_for_layer and see if it's throwing
> up an error?

Using this image spec:

'(image :type svg :data
      "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"100%\" height=\"100%\">
   <defs id=\"defs3051\">
     <style type=\"text/css\" id=\"current-color-scheme\">
       .ColorScheme-Text {
         color:#232629;
       }
       </style>
   </defs>
  <path
     style=\"fill:currentColor;fill-opacity:1;stroke:none\"
     d=\"m7.707031 3l-.707031.707031 6.125 6.125 1.167969 1.167969-1.167969 1.167969-6.125 6.125.707031.707031 6.125-6.125 1.875-1.875-1.875-1.875-6.125-6.125\"
     class=\"ColorScheme-Text\"
     />
</svg>"
      :scale 1 :width 22 :height 22)

rsvg_handle_get_geometry_for_layer returns 1, and insert-image displays
a black square of 22x22 pixels.