91776 - selection box too high, overwrites other lines

Status: VERIFIED FIXED

(Core :: DOM: Selection, defect, P2)

Description

[Miloslaw Smyk]

2001072021 Linux i/686, but it's been happening for as long as I remeber.

Please take a look at the PNG image I'm going to attach in a moment. Notice that
the bottom rasterline of three "g"s and two "y"s in the second row is overdrawn
by selection box. It looks like selection box is one rasterline to high. Also
letters _inside_ selection can get overdrawn - like "y" in "already".

It does not happen in every case, but more often than not.

Comment 1

[Miloslaw Smyk]

Attachment: PNG image demonstrating the problem.

Comment 2

[Boris Zbarsky [:bzbarsky]]

This is almost certainly a font issue akin to bug 59825...  ccing people active
on that bug

Comment 3

[kinmoz]

I agree with Boris, at first glance this like a font metrics problem. Miloslaw, 
would it be possible for you to give us a sample URL/html file that displays 
this problem?

Comment 4

[rubydoo123]

adding marc and frank to the cc list -- need their input

marc/frank -- which of you two  owns text layout?

selection is just acting upon the information it receives, all selection is
doing is saying: "give me the height of these characters" and then it inverts
the color, so if we are getting bad numbers, then we draw incorrectly

Comment 5

[Miloslaw Smyk]

Well, the example screenshot was made from

http://bugzilla.mozilla.org/enter_bug.cgi?product=Browser

I am using adobe-helvetica-iso8859-1 font. Font size in prefs is set to 15.
Display resolution is "system setting", which is "75x75 dpi" according to
xdpyinfo. I can deliver more details about my X if necessary.

Comment 6

[Hixie (not reading bugmail)]

This is probably not a bug. The selection is covering the same area as the
background would, and the background is covering exactly the right area.

You can get the same effect in other browsers if, e.g., the line-height is 
small (as in this case).

(Note that the line-height may be too small in certain cases, which is another
bug or two and which is being actively investigated already.)

Comment 7

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

See bug 91794 anyway.

Comment 8

[Miloslaw Smyk]

First: bug or not - it looks really lame and unprofessional, especially that
with other fonts the effect is even more pronounced, as more reasterlines get
overdrawn.
2nd: just checked NS4.77 and Opera 5.0 - neither of them display this problem.

Comment 9

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I'm planning to fix this.  See bug 91794.  Dup it if you want, or assign it to
me.  (It's really a dependency.)

Comment 10

[kinmoz]

Over to dbaron.

Comment 11

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Fix for bug 91794 checked in 2001-08-23 06:44 PDT.

Comment 12

[Terri Preston]

Verified fixed linux build 2001-09-17-05-0.9.4