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Garbage using Exceed when height > 32k




17 years ago
16 years ago


(Reporter: Stephane Chauveau, Assigned: Marc Attinasi)



Firefox Tracking Flags

(Not tracked)


(Whiteboard: [bae:20011218])



17 years ago
At work, I am using Exceed (a X server for NT) to access HPUX 
workstations. When using mozilla HPUX build via Exceed I found
that pages are not displayed properly when they have a large 
height. The effect is difficult to explain but basically, while
scrolling, multiple pages are displayed on top of each other 
(imagine a stack of 50 transparents). The clipping seems to 
be completly wrong and parts of other tabs are sometimes 
displayed (I will make a screenshot tomorow)

After a few experiments I found that the problem occurs when the
height of page is above than 32k pixels. For example, a 
text of 2521 lines will be displayed incorrectly. I am using 
a 12 points fonts so I guess that the total height is 

(12+1)*2521 = 32773 = 32k+5

My first reaction was to blame the HPUX build
but I have observed the same problem with a linux build 
(200110108) accessed remotely by my Exceed server.
The same build on the same linux box but using the local
XFree86 server works fine.

I suspect a limitation/bug in Exceed or in the X protocol 
(window height/clipping coded in a 16 bit integer?).
Summary: Garbage using Exceed when height > 32k → Garbage using Exceed when height > 32k
In X the window height is a 16bit value.

Comment 2

17 years ago
So why don't I see the same problem with XFRee86?

PS: by 'window height' I mean the height of the 
scrollable area (the gecko widget).  
Do you mean that you have a physical window that is 32k in size?  Do you have a
display that large or something?

Comment 4

17 years ago
iirc there are ancient posts in npm.gtk about this
Stephane, could you answer blizzard's last question, please?

This bug has had no response in a long time... since X window heights are 16bit 
values, I think this is invalid unless there's more information we should 

Comment 6

17 years ago
Houps Sorry...

No! My windows are normal (~1000x800). I have problems
with long documents whatever their visible size is on 

I have the feeling that we have a terminologie problem here :-)

Consider this document:


It contains, let's  say, 3000 thousands lines of text 
(more in fact but that's just for the example). 
With a reasonable font (e.g. 14pt) its full height in 
pixels will be something like 3000*14=42000. Of course 
I see only a small part of it (~600pixels) and I have to 
use the scrollbar to access the rest. 

That's where Exceed has a problem. The first page is 
displayed correctly but as soon as I start scrolling, 
the display is totally messed up. 

If I reduce the font size to 8pts the document height
becomes 24000 pixels (<32k) and Exceed can handle it.


Comment 7

17 years ago
I have a screenshot: 


As you can see, multiple parts of the document are 
displayed on top of each others. 

Notice the small size of the box in the right scrollbar.
That indicates that the document is very long. You can 
ignore the grey area above this scrollbar box. This is
is another minor display problem of Exceed.

To layout.  The fact that this seems Exceed-specific is very odd...
Assignee: asa → attinasi
Component: Browser-General → Layout
Ever confirmed: true
QA Contact: doronr → petersen

Comment 9

17 years ago
really strange screen shot, I am not able to test this one out Marc since I 
don't have the same set up -- sorry.
Priority: -- → P3
Whiteboard: [bae:20011218]
Target Milestone: --- → mozilla1.2
I think this is an Exceed bug. I haven't seen or heard about this on any other X
platform. Marking INVALID. Please reopen if you can demonstrate this happening
outside Exceed.
Last Resolved: 16 years ago
Resolution: --- → INVALID
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