305533 - Layered background images with palette-based transparency (GIF of PNG with tRNS chunk) display incorrectly on PocketPC

Status: RESOLVED FIXED

(Core :: General, defect)

Description

[Joshua Randall]

User-Agent:       Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7.10) Gecko/20050716 Firefox/1.0.6
Build Identifier: Mozilla/5.0 (Windows; U; Windows CE 4.20; chrome://navigator/locale/navigator.properties; rv:1.8b4) Gecko/20050805

Check the test page at: http://www.stormynight.org:8008/minimotrans/test.xhtml

Observe in particular the 2nd and 3rd columns, which show palette-based GIF and
PNG (using tRNS chunks) images layered in various configurations.  None of the
images with palette-based transparency render properly when used as background
images.  All of the same images render ok using layered <IMG> element (columns
4-6).  The same image represented as a PNG using full alpha channel transparency
(column 1) renders properly for both layered foreground and background images. 
 

Reproducible: Always

Steps to Reproduce:
1. Run Minimo on PocketPC device
2. load http://www.stormynight.org:8008/minimotrans/test.xhtml


Actual Results:  
2nd and 3rd columns do not render properly.  In most cases, the topmost image is
displayed with the transparent parts represented by black and with the rest of
the palette off as well.

Expected Results:  
The 2nd and 3rd columns should appear the same as all other columns.

Comment 1

[Jackie]

Attachment: Screenshot of part of test page for people without an iPAQ

Comment 2

[Jackie]

Attachment: Screenshot of part of test page for people without an iPAQ

Comment 3

[Jackie]

Attachment: Screenshot of part of test page for people without an iPAQ

Comment 4

[Joshua Randall]

Attachment: Tarred up version of the test page I have posted at http://www.stormynight.org:8008/minimotrans/test.xhtml

Comment 5

[Doug Turner (:dougt)]

On windows ce, alpha blending (via the AlphaBlend() function) isn't supported. 
We might be able to map AlphaBlend to use direct draw (AlphaBlt()), but I am not
sure what this means.  I know that DirectDraw is not supported at all on the
SP/PPC OSes, so the solution isn't complete.

Or maybe... we can implement AlphaBlend() without the need of direct draw.  

Comment 6

[Stuart Parmenter]

this should be fixed with cairo