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Regards
I have a problem. I cant get to refresh an image the second time it should be displayed. I am using gdi+ function Graphics::DrawImage. The image displays correctly but the second time (in a loop) the function is called the image isn't refreshed. Instead the image stays (on screen) as the first time it was drawn. I know that the image (bitmap) is changed between the two calls for DrawImage function because, when I do something with the window the image is drawn to, (like resizing it, minimizing etc.), the image is refreshed, but if I do nothing the image stays as it is the first time DrawImage draws it. I am changing image's pixels in another function named Render(), that is called before DrawImage.
Is there another function that draws image on screen, or is there a clear screen function. (I tried with graphics.Clear(color) function but after it the screen is filled with the color 'color' and again it it stays like that indefinitely)
The bitmap is created in memory and isn't read from the disk (although it's the same thing once it is in memory).
Here is part of the code which is called continously (in a loop):
void Prikaz(HDC hdc){
Graphics graphics(hdc);
Render();
Bitmap FrameBuffer((BITMAPINFO*) &((*BMPSlika).InfoHeader), (*BMPSlika).PixelData);
graphics.DrawImage(&FrameBuffer,0,0);
}
BMPSlika is a pointer to the bitmap image structure.
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It's not clear what you're using as a framework for the rest of your application, but I think you might be missing the "invalidate" call on the window after you draw to it to get it refreshed.
"Republicans are the party that says government doesn't work and then they get elected and prove it." -- P.J. O'Rourke
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I'm using .net framework, and i don't have invalidate function. is there an equivalent in .net?
I'm using MFC in standard windows libraries, in VS 2008, (VC++ 2008).
modified on Monday, January 12, 2009 11:19 AM
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I don't use .Net so I can't speak definitively about it but a quick search of MSDN.Microsoft.com shows that most .Net windows have an Invalidate function.
Um, you just confused me since you modifed your post. If you're using MFC, you have an Invalidate on your View class. Earlier, you said you didn't have MFC which would be true if you were using VS 2008 Express.
"Republicans are the party that says government doesn't work and then they get elected and prove it." -- P.J. O'Rourke
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uff sorry about that...
i searched through the project settings and found out that it is using MFC standard windows libraries... before that I hurriedly concluded, since I can't use invalidate function and I've not fount an mfc90.dll (in VS2008), that I dont have MFC... 
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there is a problem and I cant use invalidate, i'll work on that. in the meanwhile here is WndProc procedure, it might bee something here that prevents image being refreshed. I think some of the variables in PAINTSTRUCT ps, HWND hWnd, and HDC hdc are not properly set for the image to be refreshed; (firstly I think it has something to do with PAINTSTRUCT);
LRESULT CALLBACK WndProc(HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam){
PAINTSTRUCT ps;
HDC hdc;
switch(message){
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
Prikaz(hdc);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
SnimiBitmap();
return 0;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
this is WndProc process, in case it can solve my problem. I think there is something with this WM_PAINT case, it is called only when I resize, minimize, move it offscreen OR when i hold mouse pointer over the (display) window.
In first three situations when I resize, minimize, or move offscreen, the image does get refreshed, (the WM_PAINT case is executed and in it the Prikaz(hdc) iz executed which displays new image)
In the fourth situation, when I hold a mouse pointer over the display window, the WM_PAINT case is switched and the Prikaz(hdc) does get executed (including all the functions in Prikaz(hdc)), but the image doesn't get refreshed...?
this leads me to conclusion that, in situation when the mouse is over the display window, something is not "properly" set in this line, (since the Prikaz(hdc) uses argument hdc):
hdc = BeginPaint(hWnd, &ps);
I have seen the variables in ps (which is an PAINTSTRUCT structure), the hWnd (which is of HWND type) and hdc (HDC type (:lol))... In each situation they hold different values except for ps.fErase, ps.fIncUpdate, ps.fRestore. they are allways set to value 0;
there is allso ps.rgbReserved which is an pointer to an array of bytes but i'll examine it more closely.
if anyone knows about PAINTSTRUCT structure or hWnd and hdc, what is wrong with them when the image doesn't get refreshed, please let me know. in meanwhile I will try something with ps.rgbReserved, and try to get invalidate() function to include in my code, (this has something to do with .NET namespaces to do i think)....
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You mentioned something about a loop in your first post - where is this loop and
what is it (supposed to be) doing?
WM_PAINT is posted to your window's message queue by the system. The parameters are
not in your control, nor are they wrong, nor should you be trying to send/post a WM_PAINT
message yourself.
Window rendering has been the same since the beginning of Windows....the problem is in YOUR code,
not some problem in MFC (which you're not using apparently), .NET (which you're not using apparently),
or the system.
void Prikaz(HDC hdc){
Graphics graphics(hdc);
Render();
Bitmap FrameBuffer((BITMAPINFO*) &((*BMPSlika).InfoHeader), (*BMPSlika).PixelData);
graphics.DrawImage(&FrameBuffer,0,0);
}
This code has nothing to do with WM_PAINT or Invalidatexxxx() functions. The bitmap will be rendered
immediately if the HDC and the Bitmap are valid.
According to your comments, your WM_PAINT handling code is working fine, so where else are
you calling this from and how are you obtaining the HDC?
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://www.codeproject.com/script/Forums/Images/coffee.gif)
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Read the message please.
Mark Salsbery wrote: You mentioned something about a loop in your first post - where is this loop and
what is it (supposed to be) doing?
for "loop" i meant calling the Prikaz() function over again (that was in first post)
Mark Salsbery wrote: WM_PAINT is posted to your window's message queue by the system. The parameters are
not in your control, nor are they wrong, nor should you be trying to send/post a WM_PAINT
message yourself.
i'm not trying to change the message to constantly switch to WM_PAINT case, nor I said the parameters are whong (READ THE MESSAGES and then answer them if you wish to)
Mark Salsbery wrote:
Window rendering has been the same since the beginning of Windows....the problem is in YOUR code,
not some problem in MFC (which you're not using apparently), .NET (which you're not using apparently),
or the system.
the problem IS in my code (that's why I asked for help in the first place) , and there IS a problem with my .NET config in my VS.
Mark Salsbery wrote: This code has nothing to do with WM_PAINT or Invalidatexxxx() functions. The bitmap will be rendered
immediately if the HDC and the Bitmap are valid.
that code is called when the WM_PAINT message is set.
the bitmap is rendered (correctly), but only the first time the WM_PAINT is called. the WM_PAINT is called (in my program) only when i do something with the window the image is displayed in, like resizing, minimizing, holding a mouse pointer over the window.....
in the first two situations, when i resize it or minimize (and maximize ofc) the image that is displayed gets updated... (my image in the program is constantly changed in the Render() function)
in the last situation when i hold a mouse pointer over the window the WM_PAINT case gets executed, and whit it the Prikaz function, but then the image doesnt get updated.
I was asking for a way to constantly update the image when WM_PAINT is switched.
Mark Salsbery wrote: According to your comments, your WM_PAINT handling code is working fine, so where else are
you calling this from and how are you obtaining the HDC?
i dont understand you, i'm not calling it from anywhere else in my code.
LRESULT CALLBACK WndProc(HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam){
PAINTSTRUCT ps;
HDC hdc;
switch(message){
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
Prikaz(hdc, hWnd);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
SnimiBitmap();
return 0;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
i'm geting it with the BeginPaint
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OK I've gone through your posts....there's so much contradicting information it
makes it really hard to follow 
From all I can see, you are not using .NET and you're not using MFC.
If your window redraws fine when you resize it, move it, or move another window over
and then off it, then your WM_PAINT handler code is working fine.
Here's the code I have so far:
void Prikaz(HDC hdc){
Graphics graphics(hdc);
Render();
Bitmap FrameBuffer((BITMAPINFO*) &((*BMPSlika).InfoHeader), (*BMPSlika).PixelData);
graphics.DrawImage(&FrameBuffer,0,0);
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam){
PAINTSTRUCT ps;
HDC hdc;
switch(message){
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
Prikaz(hdc, hWnd);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
SnimiBitmap();
return 0;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
Prikaz() is only called from the WM_PAINT handler code, correct?
How many places is Render() called from?
If you call an Invalidate function from Render() to force a repaint of
the window (or a portion of the window) then you'll have an infinite redraw
loop, which will really slow down your UI
So if you're calling Render() perhaps from another thread that is updating the bitmap,
then the code making the call to Render() should then call an invalidate function
like InvalidateRect() to tell the system it should send another WM_PAINT.
Mark Salsbery
Microsoft MVP - Visual C++
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Yes, Prikaz is only called from the WM_PAINT handler code.
Render() is called only from Prikaz(), (that is a bit stupid, i could do completely without Prikaz())
In render() i'm just repainting the bitmap, and calling it from prikaz().
it's a problem i cant use invalidate, (someone refered to it in .net or mfc),
Mark Salsbery wrote: call an invalidate function
like InvalidateRect() to tell the system it should send another WM_PAINT.
i need that function that tells the system to send another WM_PAINT, but as i have seen in some case when WM_PAINT handler is executed, (i mean on Prikaz() in WM_PAINT handler to be executed) the image on the screen doesn't get always updated (in some cases graphics.DrawImage() does update the image and in some cases it doesn't)... i was trying to see what causes DrawImage to redraw image and how to "simulate" that condition...
i'll use InvalidateRect() as you said, it must work...
modified on Tuesday, January 13, 2009 4:45 PM
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Valdyr wrote: it's a problem i cant use invalidate
Invalidate() is specific to MFC. You need to Use one of the Win32
Invalidate functions...InvalidateRect() or InvalidateRgn(). For an instant
repaint you can call UpdateWindow() right after the Invalidatexxx call.
There's also RedrawWindow(), which combines the Invalidate and UpdateWindow
into one call, with some extra flags for finer control.
Valdyr wrote: i was trying to see what causes DrawImage to redraw image
In your case, it gets called any time you get a WM_PAINT message for your window,
since you aren't calling it anywhere else. You'll get WM_PAINT messages when an area
of the window is marked invalid, as described above, or by the system when you resize
the window larger (which invalidates the newly exposed part of the window) or move
another window off of your window.
So back to your code, if you're not getting desired results, the only place left is in
your Render() code.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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it works, thanks 
thats what i needed, InvalidateRect(), i didn't know about it in gdi.
now the image gets updated "on it's own"
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Cool!
Mark Salsbery
Microsoft MVP - Visual C++
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yeea 
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Setup a timer and call your render code from that. In your render code call the proper invalidate function to get the WM_PAINT message sent. Just remember there's not much reason to set the timer faster than your monitor can refresh the frame or you be spending rendering cycles you won't see. This way you'll get an orderly, controllable stream of screen updates and rendering cycles.
"Republicans are the party that says government doesn't work and then they get elected and prove it." -- P.J. O'Rourke
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i'll do that,
my problem was that i wasn't using invalidate function (i didn't know about other invalidate functions, just about that that is in MFC)
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Thanks for help everyone,
and the next time i'll keep it simple, and not write an essay about my problem XD
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I use glNewList() to load my drawing data, because the data is too large, i put the glNewList() into multithread, but it draw nothing using glCallList() after created the glNewList().
but if i put the glNewList() into the main thread , it draw successfully.
what is the matter? thanks.
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Please check in which thread you have created your OpenGL rendering context.
If it is in your main thread, you cannot use OpenGL calls from another thread.
If you need to do so, you will have to create seperate context for each thread and should share the context using wglShareList.
Please note that when using wglShareList the shared contexts should be made the current context of the corresponding thread using wglMakeCurrent.
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My team and I are slaving tirelessly trying to find an answer to this one: 
The guys at Ozone3D Graphics (creators of GPU Caps Viewer) have shown that it is possible to determine the number of shading processors on a GPU, and their type - example, "96 Unified SP"
We need to do just that for a medical imaging application we are working on. The number is all that's really important. I am at a loss though... The registry does not seem to contain this data, and I cannot find any evidence the OpenGL can query it.
Does anyone know how to programmatically query specifications of graphics hardware? Specially, the number of shading processors on board?
I would be very grateful for any tips.
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Please have a look on my doubt. i want to develop a SIP fone application.I think the sip communication is supported by Adobe Flash , no need to use an extra SIP stack to implement this.is it correct or not???if i am wrong, how to solve this???
Thanks in advance..
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I have an application that needs to be able to convert a jpeg into hex ascii, and then put that hex ascii into a postscript file. I know of one way to put this jpeg into postscript, but that's without using the jpeg's hex - instead, it uses a local path to a filename. I need to know two things:
1. Within a jpeg, how can I extract the hex ascii to use in postscript, in a way that postscript will understand it? Do I need all the header information? If anyone has done this before, please shed some insight. I have found the red book to be not as helpful for this specific problem as I would like.
2. Within said postscript file, how do I enter the hex of the jpeg back so that it will display properly?
Thank you very much.
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Is it possible in opengl to get a textures pixel dimensions (what was passed in to the glTexImage2D function) given a texture handle (what's returned by glGenTextures)?
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write a fragment shader, read the results in texture coordinates.
_________________________
Asu no koto o ieba, tenjo de nezumi ga warau.
Talk about things of tomorrow and the mice in the ceiling laugh. (Japanese Proverb)
John Andrew Holmes "It is well to remember that the entire universe, with one trifling exception, is composed of others."
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What about outside of a frag shader? What if I've got some code that has a handle to texture, is there a way to get the textures pix dimensions?
¡El diablo está en mis pantalones! ¡Mire, mire!
Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)!
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0 rows returned
Save an Orange - Use the VCF!
VCF Blog
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