I am upgrading from OI 16-bit to OI 32-bit (7.1) and having problems with GetDeviceCaps in GDI32.DLL

I have deleted the 16-bit objects from SysObj, amended the prototype record to reference GDI32, and run DECLARE_FCNS.

The debugger shows that zero is always being returned for BITSPIXEL, PLANES, HORZRES and VERTRES (12,14,8,10), and presumably any others.

Any thoughts on what I may be doing wrong would be appreciated.

Brian,

Can you post the prototype declaration you are using or a code example?

The Sprezzatura Group

World leaders in all things RevSoft

Prototype declaration :

GDI32

SHORT PASCAL GetDeviceCaps(SHORT, SHORT)

Usage:

Declare Function GetDeviceCaps

Declare Function GetDC

Declare Function ReleaseDC

Equ BITSPIXEL to 12

Equ NULL to ''

hDc=GetDC(NULL)

iBitsPixel=GetDeviceCaps(hDc, BITSPIXEL)

iReturn=ReleaseDC(NULL,hDc)

The debugger shows that iBitsPixel always contains zero

Many thanks

Brian,

You need to change your prototype declaration to:

INT PASCAL GetDeviceCaps(HANDLE, INT)

SHORT is explicitly a 16-bit integer whereas the GetDeviceCaps function wants 32 bit values, hence you need to use LONG or INT instead, both of which are 32-bit integers.

Note that LONG is an explicit 32-bit value, whereas INT is dependant on the underlying OS. If we ever get a 64-bit version of the engine then an INT value will translate to a 64-bit integer instead. Likewise with the HANDLE type which allows an OS-dependant handle declaration.

OI v4 and 7 introduced some new datatype declarations when prototyping , and although they haven't made it into the official documentation yet, you can find a list of them on SRPCS's website here.

The Sprezzatura Group

World leaders in all things RevSoft

Sprezzatura,

Have tested your suggestions and can confirm that it solved my problem.

Many thanks,

Brian Scarth

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