[Bug 59887] New: windowscodecs GIF decoder (CommonDecoder_Initialize) fails to load a valid multi-frame animated GIF; gdiplus then returns GenericError

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=59887

            Bug ID: 59887
           Summary: windowscodecs GIF decoder (CommonDecoder_Initialize)
                    fails to load a valid multi-frame animated GIF;
                    gdiplus then returns GenericError
           Product: Wine
           Version: 11.0
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: windowscodecs
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

## Description

Loading a particular valid animated GIF through GDI+ (`GdipLoadImageFromFile` /
`GdipLoadImageFromStream`) fails. GDI+ delegates to the builtin WIC GIF decoder
(`CLSID_WICGifDecoder`, `{1f8a5601-7d4d-4cbd-9c82-1bc8d4eeb9a5}`) and the
decoder's
`CommonDecoder_Initialize` fails, so GDI+ reports
`ExternalException: A generic error occurred in GDI+`.

When the same image is consumed by a WinForms application via designer
resources
(`ComponentResourceManager.GetObject` → `Bitmap` → `PictureBox.Image`), the
failure
surfaces later as `System.ArgumentException: Parameter is not valid` at
`System.Drawing.Image.get_FrameDimensionsList()` (called from
`ImageAnimator.CanAnimate` when the PictureBox is parented), which crashes the
app.

On native Windows the same GIF loads and animates fine.

This affects any .NET WinForms / GDI+ application that displays such GIFs. It
was
originally found because it crashes the "SpellForce 3 Universal Reforced
Content
Patch" installer at startup (its animated intro logo).

## Steps to reproduce

1. Take the attached `a_0_and_38.gif` (146 KB, 2 frames — a minimal cut of the
   original 249-frame animation that still reproduces).
2. Load it with builtin gdiplus, e.g. the attached `Repro.exe`:
   `WINEDLLOVERRIDES="gdiplus=b;windowscodecs=b" wine Repro.exe a_0_and_38.gif`

`Repro.cs` (compiled with the in-prefix csc):
```csharp
using System; using System.Drawing; using System.Drawing.Imaging; using
System.IO;
class Repro {
  static void Main(string[] a){
    using (Image img = Image.FromStream(new
MemoryStream(File.ReadAllBytes(a[0]))))
      Console.WriteLine("frames=" + img.GetFrameCount(FrameDimension.Time));
  }
}
```

## Current behavior
`System.Runtime.InteropServices.ExternalException: A generic error occurred in
GDI+.`
(builtin gdiplus + builtin windowscodecs, verified via `WINEDEBUG=+loaddll`).
The `+wincodecs` trace ends at:
```
trace:wincodecs:CommonDecoder_Initialize (...,...,1)
trace:wincodecs:CommonDecoder_Release (...) refcount=0
```
i.e. `CommonDecoder_Initialize` returns failure.

## Expected behavior
The GIF loads; `GetFrameCount(FrameDimension.Time)` returns the number of
frames
and the image animates (matches native Windows).

## Analysis / isolation
- It is **not** the native gdiplus/windowscodecs path (this report is strictly
about
  the builtin path; native DLLs are not expected to work under Wine).
- It is **not** size, total memory, or frame count: synthetic GIFs of 800x450
with up
  to 249 frames (full or partial frames, global palette, disposal=1,
min-code-size 8)
  all load fine under builtin gdiplus.
- By losslessly truncating the original 249-frame GIF (keeping the original
frame
  bytes), the failure was isolated to a **single frame, index 38 (0-based)**:
  - first 38 frames → loads OK (`trunc_38.gif`, 3.68 MB)
  - first 39 frames → fails (`trunc_39.gif`, 3.80 MB)
  - a 39-frame file where frame 38 is replaced by an earlier frame → loads OK
  - `frame 0 + frame 38` alone (146 KB, `a_0_and_38.gif`) → **fails**
- Frame 38 descriptor: position (0,27), size 800x423, no local color table
(uses the
  global 256-color table), not interlaced, LZW min code size 8, disposal=1.
Structurally
  similar to its neighbours (which load), so the trigger is in that frame's
image data /
  decode path, not an obviously malformed descriptor. The exact decode
divergence
  (likely in `dlls/windowscodecs/gifformat.c` / the bundled GIF reader used by
  `CommonDecoder_Initialize`) needs source-level debugging.

## Attachments
- `a_0_and_38.gif` — minimal reproducer (146 KB, 2 frames)
- `trunc_38.gif` (works) / `trunc_39.gif` (fails) — off-by-one-frame pair
- `pb3_exact.gif` — the full original 249-frame image (25 MB)
- `Repro.exe` / `Repro.cs` — loader

## Environment
- Wine 11.0 (Staging), Fedora 44 (x86_64)
- .NET Framework 4.8 installed in the prefix (only used to surface the original
crash;
  the bug reproduces with the plain `Repro.exe` loader above)

-- 
Do not reply to this email, post in Bugzilla using the
above URL to reply.
You are receiving this mail because:
You are watching all bug changes.