JDK-4896465 : Box drawing characters have wrong font metrics in LucidaTypewriterRegular.ttf
  • Type: Bug
  • Component: client-libs
  • Sub-Component: 2d
  • Affected Version: 1.4.0,1.4.2
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • OS: generic
  • CPU: generic
  • Submitted: 2003-07-25
  • Updated: 2017-08-29
Description

Name: dk106046			Date: 07/25/2003

java version "1.4.2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2-b28)
Java HotSpot(TM) Client VM (build 1.4.2-b28, mixed mode)

Problem also seen in 1.4.1 and 1.4.0


------------
Open the font shipped with the JDK in any font viewer program. For
example on Unix/Linux:
xfd -start 9472 -fn -jdk-lucidatypewriter-medium-r-normal--0-0-0-0-m-0-iso10646-1

This should start xfd on the page containing the characters affected.
0x2500 <==> decimal 9472.

Characters from Unicode 0x2550 to 0x256c appear to be affected.

The xfd program clearly shows the box drawing characters overlapping the
character bounding box. This is also how the affected characters appear
when displayed on Java graphical components.

The problem can be partly seen on Windows Character Map utility. However
this program clips the characters affected. Java graphical components
on Windows do not clip the characters affected - they are displayed
overlapping the character bounding box.

======================================================================

Comments
EVALUATION Name: inR10103 Date: 07/30/2003 I confirm that problem is reproducible if you select "Lucida Sans Typewriter" if Font2DTest and set unicode range to 2500-267f (affected glyphs are in range 2565-2666). I also checked other software (like Microsoft Charmap and even Fontlab) also have the problem with these glyphs because they have too big descent (comparing to font metrics). In fact font metrics for the font are: Font metrics=sun.font.FontDesignMetrics[font=java.awt.Font[ family=Lucida Sans Typewriter,name=Lucida Sans Typewriter Regular, style=plain,size=50]ascent=48, descent=11, height=59] and bounds for one of glyphs (\u2fcf) Glyph metrics=java.awt.geom.Rectangle2D$Float[x=0.0,y=-43.328125,w=20.484375,h=80.296875] Therefore: 1) i do not see any Java2D font rendering problem here (we do the best we can) 2) all code that rely on usage of FontMetrics may show these glyphs with artefacts. Generic solution (not for this particular font) depends on particular case - it could be either usage of GlyphMetrics instead of FontMetrics or clipping region outside font bounding box or something else. If these symptoms could be observed on standard AWT/Swing components then i suggest to file bugs against these components. 3) Font2DDemo also shows overlaps but i do not think this is bug because it gives impression about difference of FontMetrics and GlyphMetrics. Clipping here is not good idea because this is just hiding symptoms (that can be important to make decisions). Moreover, zoomed version of any glyph is clipped. 4) Generally speaking there is no obligation that all font glyphs are fitting into font bounding box. But because "Lucida Sans Typewriter" font is shipped with JDK and is supposed to be used with JDK it could be nice to update shipped fonts somehow (if it possible). Conclusion: I propose to recategorize this bug to those who are responsible for fonts shipped with jdk. ======================================================================
2004-06-11

WORK AROUND Name: dk106046 Date: 07/25/2003 None, for this particular font the affected characters are always displayed overlapping the bounding box because that's the information contained in the font itself. ======================================================================
2004-06-11