Re: [PATCH v2 6/6] wmphoto: Implement WmpDecoder using jxrlib.

[Esme Povirk (they/them)]

+    if (!IsEqualIID(&IID_IUnknown, iid) &&
!IsEqualIID(&IID_IWICBitmapFrameDecode, iid))
+        return E_NOINTERFACE;

This should accept IWICBitmapSource.

+        if (This->frame) IWICBitmapFrameDecode_Release(This->frame);
+        if (This->decoder) This->decoder->Release(&This->decoder);

We can't assume the caller will release the frame before the decoder.

-    *count = 0;
-    return E_NOTIMPL;
+    *count = 1;
+    return S_OK;

This should probably do something similar to what you had before where
we print a fixme if there are multiple frames.