[cairo] Cairo PDF output broken with Noto Nastaliq Urdu font

[Adrian Johnson]

On 20/11/14 08:28, Behdad Esfahbod wrote:
> On 14-11-19 03:33 AM, Adrian Johnson wrote:
>> Yes, I can have a look when I get time. The best way to ensure this does
>> not get overlooked is to file a bug. I've done this for you at:
>>
>> https://bugs.freedesktop.org/show_bug.cgi?id=86461
> 
> Thanks Adrian.  Really appreciate it.
> 

So it turned out to be an easy fix. Something I noticed while debugging
this is hb-view appears to be emitting a lot of empty glyphs. In large
documents this will unnecessarily increase the file size and increase
rendering time.

Adding some debug to cairo_show_text_glyphs and using the sample text:

کے

I get:

cairo_show_text_glyphs   num_glyphs: 5
   glyph 0: 1005
   glyph 1: 1006
   glyph 2: 1007
   glyph 3: 248
   glyph 4: 409

Using ttx I can see that

 <mtx name="glyph01005" width="0" lsb="0"/>
 <mtx name="glyph01006" width="0" lsb="0"/>
 <mtx name="glyph01007" width="0" lsb="0"/>

and

<TTGlyph name="glyph01005" xMin="0" yMin="0" xMax="0" yMax="0">
  <contour>
    <pt x="0" y="0" on="1"/>
  </contour>
  <instructions><assembly>
  </assembly></instructions>
</TTGlyph>

<TTGlyph name="glyph01006" xMin="0" yMin="0" xMax="0" yMax="0">
  <contour>
    <pt x="0" y="0" on="1"/>
  </contour>
  <instructions><assembly>
    </assembly></instructions>
</TTGlyph>

<TTGlyph name="glyph01007" xMin="0" yMin="0" xMax="0" yMax="0">
  <contour>
    <pt x="0" y="0" on="1"/>
  </contour>
  <instructions><assembly>
  </assembly></instructions>
</TTGlyph>


The cairo PS output is:

24 0 0 24 30.973638 24.414763 Tm
/f-0-1 1 Tf
-0.268014 0.635325 Td
<01>Tj
-0.355888 -0.420035 Td
<02>Tj
1.287346 -0.18717 Td
<03>Tj
-0.317223 -0.114236 Td
<04>Tj
-0.346221 0.086116 Td
<05>Tj