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Invalid DIB size calculation #3

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ForNeVeR opened this issue Apr 1, 2023 · 1 comment
Open

Invalid DIB size calculation #3

ForNeVeR opened this issue Apr 1, 2023 · 1 comment

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@ForNeVeR
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ForNeVeR commented Apr 1, 2023 •
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DeviceIndependentBitmap currently doesn't take into account the color palette stored in the DIB, which makes the size calculation incorrect. Currently it reads:

  • read 40-byte header
  • read (seemingly properly calculated amount of) data bytes into Data

But it should:

  • read 40-byte header
  • read (header.ColorsUsed ?? 1 << header.BitCount) * 4 bytes into Colors
  • read same amount of data into Data

Here's a compressed example of a file that reads incorrectly by the library: _bm0.zip.
ForNeVeR added a commit to ForNeVeR/wmf that referenced this issue Apr 1, 2023
@ForNeVeR
(papnkukn#3) DeviceIndependentBitmap: read color data
6688f39 
Without this, DIBs are read incorrectly: part of the color palette gets
mixed with the actual file data, and last bytes from the data get
completely lost.
@ForNeVeR ForNeVeR mentioned this issue Apr 1, 2023
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@ForNeVeR
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ForNeVeR commented Apr 1, 2023

I've sent a PR with a fix to the fork I use: wieslawsoltes#1. Still not sure what's the story with the fork and NuGet, though. I'm ready to send a PR to this repo as well if you want.

@ForNeVeR ForNeVeR mentioned this issue Apr 1, 2023
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