Re: [Dev-C++] trying to use AlphaBlend

Hello Per,
Great!
I have the example from MSDN working now, so I can try changing it to my 
needs.
Thanks a lot for your prompt reply!
Wobien

----- Original Message ----- 
From: "Per Westermark" <pw...@ia...>
To: "Wobien" <roo...@pl...>
Cc: "dev-cpp-users-list" <dev...@li...>
Sent: Monday, November 05, 2007 2:29 PM
Subject: Re: [Dev-C++] trying to use AlphaBlend


> MDSN?
>
> Do you mean Micro-Developers Soft Network? :)
>
> I think you mean MSDN.
>
> Yes, you have to define the WINVER define, to set the minimum version of
> Windows that your application requires.
>
> Microsoft has specifically added the WINVER define to "protect" a
> developer from by mistake using a Windows API that blocks the application
> from working on older OS.
>
> You define WINVER in the same way that you devine any other preprocesor
> data - for example by opening the project settings and add a WINVER=xx.
>
> /pwm
>
> On Mon, 5 Nov 2007, Wobien wrote:
>
>> Hi,
>>
>> I want to display bitmaps that have transparent and semi-transparent 
>> pixels
>> in a windows program.
>>
>> Searching the mdsn information on the web I found the AlphaBlend 
>> function,
>> that promises exactly what I wanted, so I gave it a try.
>>
>>
>> >From MSDN topic AlphaBlend:
>> "
>> Requirements
>> Windows NT/2000/XP/Vista: Included in Windows 2000 and later.
>> Windows 95/98/Me: Included in Windows 98 and later.
>> Header: Declared in Wingdi.h; include Windows.h.
>> Library: Included as a resource in Msimg32.dll.
>> "
>>
>> To start with, I copied an example from the mdsn site into a cpp file in 
>> my
>> project.
>> I am using windows XP, I included Windows.h, and I added libmsimg32.a to 
>> the
>> command line options for the linker in the project options and I tried to
>> compile.(I copied part of my cpp-file below)
>> The result was an AlphaBlend not declared errror.
>>
>> I checked the Windows.h and Wingdi.h files:
>>
>> >From windows.h:
>> "
>> #if !(defined NOGDI || defined _WINGDI_H)
>> #include <wingdi.h>
>> #endif
>> "
>>
>> >From Wingni.h:
>> "
>> #if (WINVER >= 0x0500)
>> WINGDIAPI BOOL WINAPI
>> AlphaBlend(HDC,int,int,int,int,HDC,int,int,int,int,BLENDFUNCTION);
>> WINGDIAPI BOOL WINAPI 
>> GradientFill(HDC,PTRIVERTEX,ULONG,PVOID,ULONG,ULONG);
>> WINGDIAPI BOOL WINAPI
>> TransparentBlt(HDC,int,int,int,int,HDC,int,int,int,int,UINT);
>> #endif
>> "
>>
>> It looks as if the preprocessor skips the declaration of AlphaBlend 
>> because
>> WINVER<0x500.
>> Do I have to inform the preprocessor about the windows version I am 
>> using?
>> And if so, how do I do that (I tried to find the answer in the on-line
>> manual on the gcc site, but didn't find anything usefull)?
>>
>> from my cpp-file:
>>
>> #include <windows.h>
>> .
>> .
>> .
>>     if (!AlphaBlend(hdcwnd, ulWindowWidth/5, ulWindowHeight/5,
>>                   ulBitmapWidth, ulBitmapHeight,
>>                     hdc, 0, 0, ulBitmapWidth, ulBitmapHeight, bf))
>>         return;                     // alpha blend failed
>> .
>> .
>>
>> Thanks for your attention,
>>
>> Wobien
>>
>>
>>
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>