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==== Using GetDeviceCaps in GDI32 (OpenInsight 32-bit Specific) ====
=== At 25 APR 2005 04:59:20AM Brian Scarth wrote: ===
 
{{tag>"OpenInsight 32-bit Specific"}}
 
<QUOTE>
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.
</QUOTE>
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=== At 25 APR 2005 05:08AM [url=http://www.sprezzatura.com]The Sprezzatura Group[/url] wrote:  ===

<QUOTE>Brian,



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



[url=http://www.sprezzatura.com]The Sprezzatura Group[/url]

[i]World leaders in all things RevSoft[/i]

[img]http://www.sprezzatura.com/zz.gif[/img]

</QUOTE>

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=== At 25 APR 2005 05:47AM Brian Scarth wrote:  ===

<QUOTE>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

</QUOTE>

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=== At 25 APR 2005 07:19AM [url=http://www.sprezzatura.com]The Sprezzatura Group[/url] wrote:  ===

<QUOTE>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 [url=http://www.srpcs.com/articles/DLL_Parameter_Types_in_OpenInsight.pdf]here[/url].



[url=http://www.sprezzatura.com]The Sprezzatura Group[/url]

[i]World leaders in all things RevSoft[/i]

[img]http://www.sprezzatura.com/zz.gif[/img]



</QUOTE>

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=== At 25 APR 2005 08:15AM Brian Scarth wrote:  ===

<QUOTE>Sprezzatura,



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



Many thanks,



Brian Scarth

</QUOTE>


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