78497 - transparent images within absolute positioned div not clipped

Status: VERIFIED FIXED

(Core :: Web Painting, defect, P2)

Description

[Simon Peter Nicholls]

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux 2.4.3-22mdk i686; en-US; rv:0.8.1+)
Gecko/20010430
BuildID:    2001043021

If clipping a div that has say 5 images in a line widthwise and you want to see
the middle 3 images, it wont clip at all. I've tried the various overflow
options. I'm using the xbdhtml cross browser code (netscapes). Under NS4/IE it
allows me a 'viewport' onto the div, but mozilla shows everything that should be
clipped off - it also activates hyperlinks for the incorrect images.

Reproducible: Always
Steps to Reproduce:
1. Use html like following:

<div id=buttons style="position:absolute; overflow:hidden">
<table cellpadding=0 cellspacing=0 border=0>
<tr>
<td><a href="link1.html">
<img src="images/button.gif" width=100 height=82>
</a></td>
<td><a href="link2.html">
<img src="images/button2.gif" width=100 height=82>
</a></td>
</tr>
</table>
</div>

2. Set a rect clip to view just the first image and clip the second off.

elt = document.getElementById("buttons")
elt.style.clip = 'rect(' + cliptop + ' ' +  
       clipright + ' ' + clipbottom + ' ' + clipleft +')';

3. Fire up browser and be dissapointed! Text works fine, images don't.

Actual Results:  Shows all images in div, complete with mouse over events

Expected Results:  Show clipped region only

Text clipping fine. Tried transparent/non-transparent - both fail. NS4 and IE fine.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Simon, could you attach a testcase?  That will greatly expedite the fixing of
this bug.

Comment 2

[Simon Peter Nicholls]

Hi, sorry about not having an attachment - It's the first time I've seen
bugzilla! I've set up a test page:

http://www.mintsource.org

Under NS4, you see 3 images at a time, on mozilla all are showed.

Cheers!

Comment 3

[Jason Johnston]

For the record-- the images are clipped properly on Win98 Build 2001050104 (only
three show at a time).  The hyperlinks are still active on images outside the
clipping area though; I don't know if this is correct behavior or not.

Comment 4

[Simon Peter Nicholls]

MacOS Build 2001032613 - 0.8.1 does the same thing as the Win98 Build
2001050104, images are clipped but hyperlinks not clipped off.

Comment 5

[Chris Petersen]

Images appear clipped correctly too under the May 8th build. Reporter, you may
want to pull a fresh build.

Comment 6

[Simon Peter Nicholls]

Still having the same problem under Linux build 2001051108. I'll check out the
mac etc builds when I get back to the office. I am suprised more people aren't
tripping over this, is this a duplicate of a different bug? This'll break quite
a few of the dhtml sites I know.

Comment 7

[Simon Peter Nicholls]

Specifying a z-index for abosulte positioned div fails. The default stacking
order determined by element declaration on page is not being overridden. This
can be seen when requiring an absolute positioned div to pop up above its
relative position i.e. negative top values.

Comment 8

[Kevin McCluskey (gone)]

Moving to Mozilla0.9.6

Comment 9

[Simon Peter Nicholls]

New URL for testing - moved the test files under bugzilla subdirectory. Changed
platform and OS to all, since all platforms I've tested show at least some of
the problems described. 

Comment 10

[Kevin McCluskey (gone)]

Works for me on WINNT, build 2001111903.
Fails on Linux. Looks like it's an issue with clipping images on Linux.

Comment 11

[Simon Peter Nicholls]

The behaviours need to be clipped off as well as the images. I have no Windows
to test whether images only are clipped.

Comment 12

[Kevin McCluskey (gone)]

Bulk moving Mozilla1.01 bugs to future-P1. I will pull from the future-P1 list
to schedule bugs for post Mozilla1.0 milestones

Comment 13

[Simon Peter Nicholls]

I retested with windows, and it's definitely only the image display that's being
clipped. Behaviours are left unclipped and also the scrollbar appears, implying
that space is being allocated for clipped off elements.

I updated the test page to http://www.mintsource.org/bugzilla btw. Cheers!

Comment 14

[Boris Zbarsky [:bzbarsky]]

I'm definitely seeing this on current linux... I'll attempt to reduce this
unholy hell of javascript to a reasonable size...

Comment 15

[Boris Zbarsky [:bzbarsky]]

Attachment: GIF image with transparency for testcase

Comment 16

[Boris Zbarsky [:bzbarsky]]

Attachment: Testcase

The problem is that opaque images are being clipped fine, but images with
transparency (I use a GIF here, but PNG does the same thing) are not clipped
correctly.

In all cases, clicking outside the clip area does not trigger links.

Comment 17

[Boris Zbarsky [:bzbarsky]]

*** Bug 158615 has been marked as a duplicate of this bug. ***

Comment 18

[Boris Zbarsky [:bzbarsky]]

This is apparently linux-only.

This bug makes using clip in mozilla somewhat painful... It looks like it just
does not work.

Comment 19

[Doron Rosenberg (IBM)]

hmm, this will probably break some site functionality, as clipped images are
being used more and more.  Can't think of a major site atm though.

Comment 20

[Scott Porter]

Not Linux only - I have had a report that it also affects (at least) the Irix 
version. 

I'm surprised this bug is only marked to be fixed at some "future" date, 
seeing as it will effectively prevent Mozilla from working with several DHTML 
libraries and create an unholy mess at other sites using dynamic content! I 
really want to support Moz with my own API (Gamelib - a library for people 
wishing to write arcade games and windowing systems using javascript) but this 
is a serious problem. I have worked around other problems, but this is a 
sticker!

I also wonder why Netscape 6 on Linux is not affected by the bug?!

Comment 21

[Boris Zbarsky [:bzbarsky]]

"Linux only" means "GTK port only" in this context.... (though it may be a
problem in the Xlib and QT ports too; if I find someone using them I'll ask).

Comment 22

[Christopher Blizzard (:blizzard)]

tor is the image king!  he can fix anything!

Comment 23

[Glenn Randers-Pehrson]

The test page http://www.mintsource.org/bugzilla looks OK to me (3 images
in view) using Mozilla 1.1b (Build ID 2002072104), Win95.  When I hit the
scroll_left or scroll_right button, scrolling and clipping happens.

Glenn

Comment 24

[Scott Porter]

Yeah, that's because it affects the *nix versions, not Windows. See the 
comments a few inches above your last one.

Comment 25

[Robert O'Callahan (:roc) (email my personal email if necessary)]

*** Bug 62543 has been marked as a duplicate of this bug. ***

Comment 26

[Robert O'Callahan (:roc) (email my personal email if necessary)]

This is not a views bug. This is an image bug. nsImageGTK simply ignores
clipping when painting images with 1-bit alpha. Look here:
http://lxr.mozilla.org/seamonkey/source/gfx/src/gtk/nsImageGTK.cpp#776
You can see that the 1-bit case creates a new GC and is just ignoring any clip
region that may have been set on aContext.

Unfortunately there doesn't seem to be a way to combine a clip mask with a clip
region in GDK, so the 1-bit case will have to take another path.

Over to tor.

Comment 27

[tor]

Attachment: clip harder if we have both a clipmask and a clip region

Comment 28

[Robert O'Callahan (:roc) (email my personal email if necessary)]

You need a call to FreeRects in there.

Comment 29

[tor]

Attachment: plug memory leak

Comment 30

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 99697 [details] [diff] [review]
plug memory leak

sr=roc+moz

Comment 31

[Stuart Parmenter]

Comment on attachment 99697 [details] [diff] [review]
plug memory leak

r=pavlov

Comment 32

[tor]

Checked in.

Comment 33

[Adam D. Moss]

Verified fixed, linux/gtkfe.  Testcases work fine.