Bug 42116

Summary:	text-rendering 'auto' output less legible that other options for some fonts
Product:	Batik - Now in Jira	Reporter:	Daniel Joyce <daniel.a.joyce>
Component:	SVG Rasterizer	Assignee:	Batik Developer's Mailing list <batik-dev>
Status:	NEW ---
Severity:	normal
Priority:	P2
Version:	1.7
Target Milestone:	---
Hardware:	Other
OS:	Linux
Attachments:	render of svg file showing problems with text-rendering="auto"

Description Daniel Joyce 2007-04-13 10:04:39 UTC

According to:
http://www.w3.org/TR/SVG/painting.html#TextRenderingProperty

"auto" is supposed to balance speed, precision, and legibility, while favoring
legibility. For some fonts though, this isn't true. I've included a sample chunk
of an affected svg document. For this font, at certain window sizes in squiggle,
the descenders on the 1 are missing when 'auto' is used, rendering it as a
single hovering 'dot'. 

This problem is not present when text-rendering is set to optimizeSpeed,
optimizeLegibility, or geometricPrecision.

				<text enable-background="new    " text-rendering="auto" transform="matrix(1
0 0 1 64.6787 71.8477)">
<tspan fill="#525759" x="0" font-size="15" y="0"
font-family="'Chalet-LondonNineteenSeventy'">1 0 1 0 1 0 1 0 1 0 1</tspan>
</text>
				<text enable-background="new    " text-rendering="optimizeSpeed" 
transform="matrix(1 0 0 1 64.6787 100.8477)">
<tspan fill="#525759" x="0" font-size="15" y="0"
font-family="'Chalet-LondonNineteenSeventy'">1 0 1 0 1 0 1 0 1 0 1</tspan>
</text>
				<text enable-background="new    " text-rendering="optimizeLegibility"
transform="matrix(1 0 0 1 64.6787 130.8477)">
<tspan fill="#525759" x="0" font-size="15" y="0"
font-family="'Chalet-LondonNineteenSeventy'">1 0 1 0 1 0 1 0 1 0 1</tspan>
</text>
				<text enable-background="new    " text-rendering="geometricPrecision"
transform="matrix(1 0 0 1 64.6787 160.8477)">
<tspan fill="#525759" x="0" font-size="15" y="0"
font-family="'Chalet-LondonNineteenSeventy'">1 0 1 0 1 0 1 0 1 0 1</tspan>
</text>

Comment 1 Daniel Joyce 2007-04-13 10:08:55 UTC

Created attachment 19952 [details]
render of svg file showing problems with text-rendering="auto"

This file contains the 4 sample text lines included in the bug report,
consisting of repeating 1's and 0's. From top to bottom, the text-rendering
options are "auto", "optimizeSpeed", "optimizeLegibility" and
"geometricPrecision".

As the squiggle window is resized, parts of the 1's disappear and reappear when
'auto' is set. The bug is not seen for the other text-rendering property
settings.

Comment 2 Daniel Joyce 2007-04-13 10:10:12 UTC

I can't attach the font itself because it is not a freeware or pd font file.