400603 - Last row of bottom-up bitmap is never updated

Status: RESOLVED FIXED

(Core :: Graphics: ImageLib, defect)

Description

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The rect that nsBMPDecoder::ProcessData updates is off by one pixel in the bottom-up case. In the top-down case it appears to be completely wrong.

Comment 1

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Attachment: Testcase

Comment 2

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Attachment: Testcase

Comment 3

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Attachment: Proposed patch

In the bottom-up case mCurLine is simply the index of the last fully decoded line, so we use it as the top of the rectangle (mOldLine is effectively the bottom of the rectangle, whose height is of course mOldLine - mCurLine).
The top-down case is slightly different because of the y-axis reflection. Not only do the top and bottom have to be subtracted from the height, but they also have to be exchanged since the bottom (which was mOldLine) is now the top.
I also fixed an abuse of PR_FALSE as an nsresult.

Comment 4

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Comment on attachment 285657 [details] [diff] [review]
Proposed patch

Regression fix, but presumably not M9 urgent, due to the comparative infrequency of bitmaps on the web.

Comment 5

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Fix checked in.