Bug 6019

Summary:	RenderAddGlyphs fails with BadLength
Product:	cairo	Reporter:	Chia-I Wu <b90201047>
Component:	xlib backend	Assignee:	Carl Worth <cworth>
Status:	RESOLVED FIXED	QA Contact:	cairo-bugs mailing list <cairo-bugs>
Severity:	normal
Priority:	high	CC:	abelcheung
Version:	1.1.1
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	mixed outline/bitmap glyphs

Description Chia-I Wu 2006-02-24 05:35:12 UTC

Hi,

cairo uses the same GlyphSet to render all glyphs of a scaled font (see
`_cairo_xlib_surface_add_glyph' in cairo-xlib-surface.c.  As a GlyphSet requires
all glyphs to be of the same PictFormat, this can cause problems with
bitmap/outline mixed fonts.

For example, the most widely used traditional Chinese font, AR PL New Sung[1],
has mixed bitmap/outline glyphs at size 15px.  When try to render glyphs of that
size, cairo fails with the following error message:

X Error of failed request:  BadLength (poly request too large or internal Xlib
length error)
  Major opcode of failed request:  157 (RENDER)
  Minor opcode of failed request:  20 (RenderAddGlyphs)
  Serial number of failed request:  24
  Current serial number in output stream:  29

[1]: http://cle.linux.org.tw/fonts/FireFly/fireflysung-1.3.0.tar.gz

Comment 1 Chia-I Wu 2006-02-24 05:38:21 UTC

Created attachment 4737 [details]
mixed outline/bitmap glyphs

The uppercase roman numbers are bitmaps (depth=1) and the lowercase ones are
outlines (depth=8, anti-aliased)

Comment 2 Chia-I Wu 2006-02-25 21:20:34 UTC

In Xft, those outlines are rendered with anti-alias off.  All glyphs, bitmaps or
outlines, are thus of format PictStandardA1 and everything works well.  
Actually, I do turn anti-alias off in fontconfig's config file (so that the
embeded bitmaps are used when available).

<match target="font">                                                          
                                             
        <test qual="any" name="family" compare="eq">                           
                                             
                        <string>AR PL New Sung</string>                        
                                             
        </test>                                                                
                                             
        <test name="pixelsize" compare="less_eq">                              
                                             
                <double>16.5</double>                                          
                                             
        </test>                                                                
                                             
        <edit name="antialias" mode="assign">                                  
                                             
                <bool>False</bool>                                             
                                             
        </edit>                                                                
                                             
</match>                                                                       
                                             

Don't know why cairo still renders outlines with anti-alias.

Comment 3 Chris Wilson 2008-04-07 07:34:49 UTC

I believe this to be fixed by, in particular, commit 805b668260c47e6d3d854361fcc53f12bd2a57e1 and the work to resolved bug 13479.

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