Qt and the Win32 API

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laserbeak43

Beginner

Posts: 27

Wednesday, May 7th 2008, 5:54am

Qt and the Win32 API

Hi,
I've been wondering, I have some example code that i'm looking at that seems to use HINSTANCE and these includes

	Source code
1 2 3 4 5	#define WIN32_LEAN_AND_MEAN #include <windows.h> #include <iostream.h> #include <fstream.h> #include <string.h>

here's the main issue so far:
I'm having a hard time figureing out what Qt's version(if any) of HINSTACE would be. for example, the code says:

	Source code
1	HINSTANCE libhandle=LoadLibrary("c:\\program files\\steinberg\\vstplugins\\muon\\cm101.dll");

now i know i can use QLibrary() to load .dll files from reading assistant. But will i be using it in the proper context if i don't find Qt's "equivalent" function?

i have "C++ GUI Programming with Qt 4" and it has a few pages on Qt and the Win32 Api, including a list of Windows functions and their Qt equivalents, but i don't see HINSTANCE here(there were only 7 different entries).

Can anyone help me out with this please?

mjimenez

Beginner

Posts: 18

Wednesday, May 7th 2008, 8:40am

RE: Qt and the Win32 API

I'm not sure if I am understanding your problem but I think that you have to forget HINSTANCE. Just use QLibrary to load the library, what else do you need?

	Source code
1 2 3 4 5 6 7	QLibrary myLib("c:\\program files\\steinberg\\vstplugins\\muon\\cm101.dll"); myLib.load(); if (myLib.isLoaded()) { // use myLib.resolve("...") to load the functions }

Best regards,

Manuel

laserbeak43

Beginner

Posts: 27

Wednesday, May 7th 2008, 2:19pm

RE: Qt and the Win32 API

not exactly sure, but your example looks simple enough, thanks

laserbeak43

Beginner

Posts: 27

Wednesday, May 7th 2008, 3:44pm

RE: Qt and the Win32 API

i'm not sure if declaring this "main is such a good idea yet, since i'm used to main looking a bit different from the Qt book that i'm learning from. but the last line of code is what i'm worried about at this point. GetProcAddress() seems to be a function i would use if i were using LoadLibrary() to open the file. Qt Assistant notes a similar function, oid * QGLContext::getProcAddress ( const QString & proc ) const, but this is for OpenGL. which should i use?

so far, i have written:

Source code

#include <QLibrary>

#include "audioeffectx.h"

const int blocksize=512;
const float samplerate=44100.0f;

long VSTCALLBACK host(AEffect *effect, long opcode, long index, long value, void *ptr, float opt);

void main() 
{
	/////////////////////////////////////////////////////////////////////
	//
	///					Loading a plugin
	//
	////////////////////////////////////////////////////////////////////

	//create a pointer for the plugin we're going to load
	AEffect* ptrPlug = NULL;
	bool editor;

	//find and load the DLL and get a pointer to is main function
	//this has a prototype like this: AEffect *main(audioMaterCallback audioMaster)

	QLibrary theVst("C:\\Program Files\\VstPlugins\\Crystal.dll"};

	if (theVst.isLoaded())
	{
		//DLL was loaded OK
		AEffect* (__cdecl* getNewPlugInstace) (audioMasterCallback);
		getNewPlugInstance=(AEffect*(__cdecl*)(audioMasterCallback))GetProcAddress(theVst, "main");

mjimenez

Beginner

Posts: 18

Wednesday, May 7th 2008, 4:07pm

RE: Qt and the Win32 API

First of all, theVst.isLoaded() will return false unless you call theVst.load() before (only creating the object QLibrary doesn't work for me).

After that, I think you have to call...

Quoted

getNewPlugInstance = (AEffect*(__cdecl*)(audioMasterCallback)) theVst.resolve("main");

... to load the method.

Best regards,

Manuel

laserbeak43

Beginner

Posts: 27

Wednesday, May 7th 2008, 4:25pm

RE: Qt and the Win32 API

thanks for catching that load() function for me

yeah, that makes more sense, i'm looking at resolve right now in Qt Assistant.

all this talk of symbols in my years of C++ yet i'm still not even sure what a symbol is...