Do windows handles remain 32 bits in x64?

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COM Developer - 07 Sep 2005 17:00 GMT

I have a few COM interfaces which use the OLE_HANDLE type to pass HWNDs or
HBITMAPs. Several Microsoft defined interfaces also use OLE_HANDLE (e.g.
IPicture::get_Handle), but in VS.NET 2005, OLE_HANDLE is still 32 bits!

Wondering about this, I created a simple experiment where I create very
large numbers of windows or bitmaps. In both cases, I never received a
handle which could not be represented in 32 bits (never exceeded 0xFFFFFFFF).
Is this a guarantee on x64? If not, how can Microsoft’s picture object
continue to work?

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COM Developer - 07 Sep 2005 17:33 GMT

Clarification:

Using VS.NET 2005 to produce 64 bit binaries.

> I have a few COM interfaces which use the OLE_HANDLE type to pass HWNDs or
> HBITMAPs. Several Microsoft defined interfaces also use OLE_HANDLE (e.g.
[quoted text clipped - 5 lines]
> Is this a guarantee on x64? If not, how can Microsoft’s picture object
> continue to work?

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Mikhail Arkhipov (Microsoft) - 07 Sep 2005 19:10 GMT

On 9/7/05 9:33, in article
20510371-415C-4482-A251-DF384CA32468@microsoft.com, "COM Developer"
<COMDeveloper@discussions.microsoft.com> wrote:

> Clarification:
>
[quoted text clipped - 9 lines]
>> Is this a guarantee on x64? If not, how can Microsoft¹s picture object
>> continue to work?

AFAIK, yes, handles are still 32 bits. This guarantees that 32-bit app can
still send messages to 64 bit app window and OLE/RPC (or at least parts of
it) works across applications with different bitness.

Thanks
Mikhail Arkhipov (Microsoft)
-- This post is provided 'AS IS' with no warranties and confers no rights

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Do windows handles remain 32 bits in x64?

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