148551 - SetImageData/SetAlphaData incorrectly converting offset on XP_PC

Status: VERIFIED FIXED

(Core Graveyard :: Image: Painting, defect)

Description

[ArronM (:paper)]

SetImageData & SetAlphaData (mozilla/gfx2/src/) assume aOffset is referencing
data in a top-down manner.  PCs (XP_PC) use a bottom-up storage, so these
functions adjust the passed in offset to the proper top-down position. The
current code does not take into account an offset within the middle of a row.

Simple Example to help clarify:
We want to set (1,0) to (7,0) on a 8x11 image.
Let's assume 1 byte == 1 pixel for simplification of calculations.  This will
result in a 88 byte image (positions 0 to 87).
We call SetImageData(data, 7, 1) (data, numBytes, top-down offset)

For XP_PC, top-down needs to be converted to bottom-up..

Expected Result: position 81 to 87 of imgData should be set to the new data
Expected newOffset: 81

Currently SetImageData calculates
newOffset = ((mSize.height - 1) * row_stride) - aOffset;
newOffset = (10 * 8) - 1
newOffset = 79
Actual Result: position 79 to 85 (inclusive) of imgData will be set to new data


Upcoming patch will fix this problem

Comment 1

[ArronM (:paper)]

Correction to line 3 of Description:

these functions adjust the passed-in offset to the proper _bottom-up_ PC storage
position.

Comment 2

[ArronM (:paper)]

ccing pav & tor

pav, tor, I'll need this r='d, sr='d, and checked-in before Bug 85595

Comment 3

[ArronM (:paper)]

Attachment: Correctly set newOffset

Comment 4

[Mike Young]

confirming to get this on radar

Comment 5

[tor]

Comment on attachment 85964 [details] [diff] [review]
Correctly set newOffset

sr=tor

Comment 6

[ArronM (:paper)]

pav, can you r=?

Comment 7

[Stuart Parmenter]

Comment on attachment 85964 [details] [diff] [review]
Correctly set newOffset

r=pavlov

Comment 8

[Stuart Parmenter]

checked in on the trunk.

Comment 9

[Blake Ross]

Fixed on branch, because adt+ bug 85595 depended on this.

Comment 10

[Terri Preston]

Verified patch checked into lxr.mozilla.org(trunk) and bonsai.mozilla.org(branch)