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Bug 125220

Summary: Tab char position miscalculated in Java editor
Product: [Eclipse Project] Platform Reporter: Frits Jalvingh <jal>
Component: SWTAssignee: Felipe Heidrich <eclipse.felipe>
Status: RESOLVED DUPLICATE QA Contact:
Severity: normal    
Priority: P3 CC: billy.biggs, daniel_megert
Version: 3.2   
Target Milestone: ---   
Hardware: PC   
OS: Linux-GTK   
Whiteboard:
Attachments:
Description Flags
Picture of a text selection rendered badly none

Description Frits Jalvingh CLA 2006-01-25 14:02:40 EST 
I use tabs for indent (not spaces) in the Java editor. In many cases the "next tab position" will be miscalculated: instead of moving to the actual new position the text moves only about a single pixel. It looks like the string length calculation calculates a pixel size that's one too small. If I use a space instead of a tab then the cursor does advance proper. An example as it looks on the screen:

private Mama<String> m_blarf;
private List<String>m_attr_l;

The first line contains the space just before the m_; the second one contains the tab which should move way beyond the start position of the m_blarf text.

This bug is visible on both x86-gtk and amd64-gtk, and it occurs on most Eclipse versions. My editor font is Bistream Vera Mono; I'm running Gentoo Linux with X 6.8.2-r6, freetype 2.1.9-r1, pango 1.10.2 (I have no idea what other stuff is used to render the text ;-)
Comment 1 Frits Jalvingh CLA 2006-01-25 14:10:31 EST 
Some extra info:
- It goes wrong on Bitstream Vera Mono 10pt but it goes well on some other sizes
- Fonts that also fail on 10pt are Nimbus Mono L and Monospace
- Fonts that work well at 10pt are Luxi Mono, Terminal and Lucida Typewriter.
My screen resolution as reported by xdpyinfo is:
  dimensions:    1600x1200 pixels (411x311 millimeters)
  resolution:    99x98 dots per inch
Comment 2 Dani Megert CLA 2006-01-26 03:07:26 EST 
What's the build ID of your Eclipse install?
Comment 3 Frits Jalvingh CLA 2006-01-29 10:04:52 EST 
My eclipse build is: Version: 3.1.1
Build id: M20050929-0840
but again: it is in the newer versions too.

And a "fix" for my previous comment: the fonts I described as not having the problem *do* have the problem, only at different positions.. That is some tabs behave properly while others do not, and which tabs misbehave depends on the font..
I will also attach an image of how selecting a text region looks on my screen: it leaves bars at the end of characters which may point to the same problem (calculating string widths seems to be off by 1 pixel).
Comment 4 Frits Jalvingh CLA 2006-01-29 10:05:54 EST 
Created attachment 33766 [details]
Picture of a text selection rendered badly
Comment 5 Felipe Heidrich CLA 2006-02-16 12:26:43 EST 

*** This bug has been marked as a duplicate of 123425 ***