183405 - Large images will not display under some scaling ratios.

Status: RESOLVED WORKSFORME

(Core :: Graphics: ImageLib, defect)

Description

[adrian]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3a) Gecko/20021203
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3a) Gecko/20021203

Large images that can be displayed in mozilla disapper when scaled.  This only
occurs when one of the axis is scaled and the other is left for mozilla to
calculate.  This is caused by an overflowing interger multiply in
layout/html/base/src/nsImageFrame.cpp on lines 863 and 867.

Reproducible: Always

Steps to Reproduce:
1. load the attached page (up coming)
2. notice that the image loads fine.
3. click on one of buttons labled "2000(broken)"
4. notice that the image goes away.

Actual Results:  
The image went away

Expected Results:  
display the scaled image

This bug was discovered at the project guttenberg website.
Don't shift reload the attached page--this crashed mozilla(separate bug)

I will attach the testcase and the patch soon.

Comment 1

[adrian]

Attachment: image to scale

Comment 2

[adrian]

Attachment: the webpage

Here is the webpage to test.

Comment 3

[adrian]

Attachment: patch

Ok what is going on here is mozilla is calculating height or width of an image.
 This is acomplished by a multiply and a divide.  The current code does the
multiply first, I assume, to avoid an underflow.  However it does not defend
against an overflow.  What the patch does is to check for potential overflows,
and if one will occur then it does the divide first.

Comment 4

[adrian]

Attachment: new better patch, passes JST Review Simulacrum

Added a macro and cleaned up whitespace

Comment 5

[adrian]

Attachment: a test case that is simpler to use

This testcase is simpler to user.  Perhaps someone can verify the bug now.

To see bug
1) Load this testcase.
2) Notice that the image displays.
3) Pick an atribute to change, for example the picture's width.
4) Click on the button labeled 690, notice that the image scales to be 690
pixels wide.
5) Click on the button labeled 6213, notice that the image scales to be 6213
pixels wide.
6) Click on the button labeled 6214(fails), notice that the image fails to
display.

Can be repeated for the height attribute, but reload first.

Comment 6

[Stephanie Daugherty [:sdaugherty]]

WFM on Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9a5pre) Gecko/20070508 Minefield/3.0a5pre - may have been fixed by the reflow landing, I'm not sure. 

Comment 7

[adrian]

Original reporter here:
WFM on Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a5pre) Gecko/20070511 Minefield/3.0a5pre

Also as noted by Stephanie, works on Linux with minefield, was broken in Gran Paradiso, but now fixed in Minefield, so being fixed by the reflow landing sounds like a good guess.