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Get Window Handle in OpenGL (and on Mac)

BlitzMax Forums/BlitzMax Programming/Get Window Handle in OpenGL (and on Mac)

Grey Alien(Posted 2009) [#1]
Hi, does anyone know how to get the Window Handle of a Graphics window made in BMax in OpenGL using Graphics W,H,0 ?

I can do it in DirectX like this:

	Method GetActiveWindowSafe%()
		'For Win32 only.
		'GetActiveWindow() 'This old method is sometimes unreliable! (e.g. if another window gets focused when this one is being created.)
		'Use new more reliable method.
		Local my_driver:TD3D7Graphicsdriver=D3D7GraphicsDriver()
		Local my_graphics:TD3D7Graphics=my_driver.Graphics()
		Return my_graphics._hwnd
	End Method


And as you can see I don't want to use GetActiveWindow() as it is not always accurate (I can mess it up by clicking away from the MaxIDE as the game is compiling for example).

I recall the person who helped me with this code in the first place saying that the hwnd for OpenGL was not stored in the Blitz modules, so would I need to make a module mod to get it? (Maybe BRL can, fingers crossed!)

Also how can a similar thing be done on Mac? I'm using this Objective C code in a .m file:

NSWindow* macGetActiveWindow(){
    NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init];
    NSApplication *myApp;
    myApp=[NSApplication sharedApplication];
    NSWindow *myWindow = [myApp keyWindow];
    [pool release];
	return myWindow;
}


Then I'm passing that to another objective C function to get the window origin:

void macGetWindowOrigin(NSWindow *myWindow, int *x, int *y){
    NSRect myFrame = [myWindow frame];
    *x = myFrame.origin.x;
    *y = myFrame.origin.y;
}


But basically it has the same issues where you can take the focus away from the game as it compiles and then you end up getting the window stats for a different window!

Any help much appreciated thanks! This code will make it into the next framework update for my customers.


therevills(Posted 2009) [#2]
I would love to help GA... but I haven't got a clue! Anyone else?


Brucey(Posted 2009) [#3]
it has the same issues where you can take the focus away from the game

Well, indeed... because *your* window isn't always the active window :-p


Ideally, retrieving the window handle would be part of the API - why not, it's probably useful to some people.
It's actually very easy then to access a handle if you have a built-in function to get it from :-)


However, I dunno if Mark will be taking any more of my "hacks" for a while, since I've kind of flooded him with lots of them lately...

In answer to the original question:
does anyone know how to get the Window Handle of a Graphics window made in BMax..

the answer is yes, but best implementation would be to add a new Function you can call :-)


Brucey(Posted 2009) [#4]
Perhaps something like this knocked together snippet :

SuperStrict

Import "glue.m"

Extern
	Function macGetWindowOrigin(window:Int, x:Int Var, y:Int Var)
End Extern



Graphics 800, 600, 0


Local handle:Int = GraphicsWindowHandle()


SetColor 255, 255, 255

While Not KeyDown(key_escape)

	Local x:Int, y:Int
	macGetWindowOrigin(handle, x, y)


	Cls
	
	DrawText "hello", 10, 10
	
	DrawText x + ", " + y, 200, 200
	
	Flip


Wend

where GraphicsWindowHandle() returns the handle to the window - if there is one.
Running here on the Mac (OpenGL) :-)
(note that on OS X, origin is in bottom-left corner of the screen, so you would need to do some math on y)

Requires changes to BRL.Graphics, BRL.GLGraphics, BRL.GLMax2D ... and related modules.


Brucey(Posted 2009) [#5]
With modifications to BRL.dxgraphics and BRL.d3d7max2d, GraphicsWindowHandle() seems to cover all Windows possibilities.


What would one really want the window handle for anyway?


Tommo(Posted 2009) [#6]
You can get the hwnd without modifying BRL module. Just do some copy work.
C side:
#include <windows.h>
/* copied from BRL.glgraphics */
typedef struct BBGLContext{
	struct BBGLContext *succ;
	int mode,width,height,depth,hertz,flags;
	HDC hdc;
	HWND hwnd;
	HGLRC hglrc;
} BBGLContext;


HWND getGLhwnd(BBGLContext *c){
	return c->hwnd;
}


BMX side:

Import "glhwnd.c"
Extern
	Function getGLhwnd:int(c:Int)
End Extern

'test
Local g:TGLGraphics = TGLGraphics(GLGraphics(640, 480)) 'get GLGraphics
print getGLhwnd(g._context)

This works on win32. No idea about Macos (since I don't have one).


Brucey(Posted 2009) [#7]
Yeah, or you can have lots of different functions to get the same information :-)


Grey Alien(Posted 2009) [#8]
@Tommo: Wow that seems pretty neat! I haven't tried it out yet though. So that's a non-module hack solution, which is my perference. I can try it on Mac too.

@Brucey: Yeah that command you've invented would be fantastic. I often use the window handle to pass to various Windows and Mac API functions. For example I get the moues cursor relative to the desktop so I can slide it smoothly in and out of the BMax window. Also I like to reposition the window centrally on the desktop. I know there are module hacks for those (which you specialise in) but I prefer not to do them as I'd have to re-do them after every BMax update and also get anyone else using my framework to do them. I know it's a self-imposed resistance to a useful solution though...


Brucey(Posted 2009) [#9]
I can try it on Mac too.

You'll need even more code for the Mac version, I'm afraid :-)

Also I like to reposition the window centrally on the desktop.

I've been trying to get those hacks integrated officially, but things are going slowly...

but I prefer not to do them

I completely understand... which is why these things should really be part of BlitzMax proper.


Grey Alien(Posted 2009) [#10]
You'll need even more code for the Mac version, I'm afraid :-)
Ah yes, should have noticed the include windows.h

which is why these things should really be part of BlitzMax proper.
Indeed. Let's hope they get added one day...


Grey Alien(Posted 2009) [#11]
Brucey: Do you think it's possible to do a similar thing to Tommo's code on the Mac? As in not have to make module changes?


Brucey(Posted 2009) [#12]
Probably :-)


Grey Alien(Posted 2009) [#13]
OK cool, we'll this may have to be something I investigate later.