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  • GDIPlus - add a webp image decoder ?

    From R.Wieser@21:1/5 to All on Sun Nov 26 09:43:40 2023
    XPost: comp.os.ms-windows.programmer.win32

    Hello all,

    Some time ago I stumbled over a few webp images. After some some
    websearching I found a dll which could decode them into a raw byte arrays,
    and with help of GDI+ I was able to save that into a native format (jpg,
    png, etc), allowing me to view the resulting images.


    While doing the above I was (again) made aware that GDI+ has(?) installable image decoders & encoders. So, I thought it would be an idea to see if I could write-and-install a webp decoder to that list.

    The thing is, I can't seem to find anything of worth regarding native GDI+ installable image decoders, and only very little about a WIC type of
    decoder. At least not enough to be able to get a complete picture about
    what needs to be done.


    So, I'm wondering if anyone here knows anything about how to create, preferrably, a native GDI+ decoder - though information about how to create
    WIC type of decoder is quite welcome too. (I'm an Assembly programmer, which
    is why I rather work with the former than the latter)

    Regards,
    Rudy Wieser

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  • From JJ@21:1/5 to R.Wieser on Mon Nov 27 10:59:09 2023
    XPost: comp.os.ms-windows.programmer.win32

    On Sun, 26 Nov 2023 09:43:40 +0100, R.Wieser wrote:
    Hello all,

    Some time ago I stumbled over a few webp images. After some some websearching I found a dll which could decode them into a raw byte arrays, and with help of GDI+ I was able to save that into a native format (jpg,
    png, etc), allowing me to view the resulting images.

    While doing the above I was (again) made aware that GDI+ has(?) installable image decoders & encoders. So, I thought it would be an idea to see if I could write-and-install a webp decoder to that list.

    The thing is, I can't seem to find anything of worth regarding native GDI+ installable image decoders, and only very little about a WIC type of
    decoder. At least not enough to be able to get a complete picture about
    what needs to be done.

    So, I'm wondering if anyone here knows anything about how to create, preferrably, a native GDI+ decoder - though information about how to create WIC type of decoder is quite welcome too. (I'm an Assembly programmer, which is why I rather work with the former than the latter)

    Regards,
    Rudy Wieser

    You can learn from examples, such as below PGM WIC codec.

    https://github.com/vbaderks/netpbm-wic-codec

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  • From R.Wieser@21:1/5 to All on Mon Nov 27 08:08:45 2023
    XPost: comp.os.ms-windows.programmer.win32

    JJ,

    So, I'm wondering if anyone here knows anything about how to create,
    preferrably, a native GDI+ decoder - though information about how to
    create
    WIC type of decoder is quite welcome too. (I'm an Assembly programmer,
    which
    is why I rather work with the former than the latter)

    You can learn from examples, such as below PGM WIC codec.

    https://github.com/vbaderks/netpbm-wic-codec

    Thanks for the link.

    Thoug part of the problem with the WIC style approach is that I would need
    to figure out what the methods and properties of each of the used objects is (in vtable order!) - which is normally not something thats part of such an example.

    (I've had to do similar often enough to know its a hit-or-miss kind of thing trying to google for it ...)

    Nonetheless, its more than I had before. :-)

    Regards,
    Rudy Wieser

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  • From JJ@21:1/5 to R.Wieser on Tue Nov 28 08:12:04 2023
    XPost: comp.os.ms-windows.programmer.win32

    On Mon, 27 Nov 2023 08:08:45 +0100, R.Wieser wrote:

    Thanks for the link.

    Thoug part of the problem with the WIC style approach is that I would need
    to figure out what the methods and properties of each of the used objects is (in vtable order!) - which is normally not something thats part of such an example.

    (I've had to do similar often enough to know its a hit-or-miss kind of thing trying to google for it ...)

    Nonetheless, its more than I had before. :-)

    AFAIK, in the reference part of Microsoft SDK documentations, the list of methods of an interface is always in VTable order. You can still check the relevant C header file if you have doubts.

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  • From R.Wieser@21:1/5 to All on Tue Nov 28 07:54:55 2023
    XPost: comp.os.ms-windows.programmer.win32

    JJ,

    AFAIK, in the reference part of Microsoft SDK documentations, the
    list of methods of an interface is always in VTable order. You can
    still check the relevant C header file if you have doubts.

    As mentioned, I've googled quite a bit in search of how to "talk to"
    objects. And it always was a problem finding the vtbale information, even
    for common MS objects.

    But if you know where I can find on-line Microsoft SDK documentation I would
    be much obliged.

    Currently the most pertinent information I can find is learn.microsoft.com,
    but even that one has its problems. Just yesterday I was having a problem
    with a standard GDI+ function, GdipCreateBitmapFromScan0 . Try to find some
    MS documentation about it (and its sibblings) and you get nowhere fast. :-(

    Regards,
    Rudy Wieser

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