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KCMANDAL wrote: very important
So, you're "very important"?? Don't you think that's a bit arrogant of you to declare?
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I try to display the content of client area of window A on the window B.
void SimpleDlg::OnButton3()
{
HWND hWnd=NULL;
hWnd=::FindWindow("l2UnrealWWindowsViewportWindow", NULL);
HDC hdcLin=::GetDC(hWnd);
HDC hdcWin=::GetDC(this->m_hWnd);
::BitBlt(hdcWin,
0,0,
300, 300,
hdcLin,
600,400,
SRCCOPY);
::ReleaseDC(hWnd, hdcLin);
::ReleaseDC(this->m_hWnd, hdcWin)
}
this code looks fine, but it works only once. when a pircture is changed on the window A and then function OnButton3 is run again, previous content of window A will be displayed. DC of window A is updated only when i close window A and open a new one. do i have to refresh somehow DC of window A in order to have always the most recent context?
thank you in advance.
radek
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Hii there.. i wondering whether u have an solution already for "refresh device context" problem, if u do please let me know, because i have the same problem. Thanks for share.
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Hello,
I'm communicating with a logic analyzer (HP 1660A) over RS232. I issue a command which tells the analyzer to print screen its display and send it over to the controller (my pc) through serial communication. I'm saving the result (which is usually abut 25kB) to my computer and I would like to view it as a TIFF or other format. The problem is that the response from the analyzer comes in PCL format, therefore suitable to be sent to a printer and printed directly, but not to be opened as an image. I have tried a few PCL to image converters to do the job, I found one which does it properly, however I've used the trial version and I am reluctant to purchase it. I've given you the background of my labour. I would appreciate any kind of help, a reference to the commands in pcl 1 and what should I do in order to extract the data and format it properly from the PCL file. I have no experience with PCL and image processing whatsoever, so please, give me a hand here. Thank you.
P.S. I've obtained the PCL file from the analyzer, both in C# and matlab... I have one slight problem in C# with the serial port control, some images have some uninterpreted characters in the image, when using the above converters. I say all these because I need an algorithm or some indications, no matter the programming language, so please feel free to post.
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Hi,
i have written a shadder program like wrapEffect available on codeproject.com which i am using in wpf to distort images.
i want to know is it possible that in shader we can translate vertext to any direction.
currently it seem that we can translate vertext to only straight direction within a ratio of 0 to 1..
is there any way to do so..
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Hi;
I downloaded Directx SDK November2008 release. in SDK I got some samples when I compile that samples it is compiling ok, but when I run this sample it is giving this error.
"The procedure entry point __CxxFrameHandler3 could not be located in the dynamic link library"
if any body have solution for this problem it would be thank full.
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I'm developing a vector graphics app and I'm trying to find the most efficient way to scale a rotated shape. As an example, lets say the user adds a rectangular shape to the drawing surface. Once they rotate the shape to, say 45 degrees, how can I most effeciently perform scaling once they decide to resize the shape?
My current solution is to get the amount of pixels the mouse has moved, then rotate the shape back to 0 degrees, then offset the points by the delta amount, then rotate the points back to the current rotation. I don't think this is the best method because if the user has created a complex polygon and rotates it, I may end performing thousands of calculations!
Can anybody help me?
My code this week has no errors. But it's Monday morning and I haven't got out of bed.
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Hi,
this is one approach:
- create an abstract base class that represents a drawable item; give it a Transformation Matrix member that initially is set to the unity matrix.
- derive all drawable items (lines, rectangles, circles, ...) from it; in the Paint handler, apply the transformation matrix to your Graphics object before drawing the object.
- when one or more drawable items are selected and a transformation gets ordered (translation, rotation, scaling) adjust the matrix for each selected object, i.e. calculate the matrix that represents the new transformation and combine it with the individual matrices.
The main problem that remains now is mapping mouse positions to the relevant drawable item;
there is no inverse matrix so you can't directly go from mouse position to item; you have to enumerate the items, for each enumerate the clickable parts (points, edges, surfaces), apply the transformation to them and check for a mouse hit.
Hope I made this sufficiently clear.
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Thanks for the reply.
I've toyed around with using the matrix class but I can't seem to justify transforming a whole collection of shapes every time I need the coordinates. The transforms would also have to be applied on every paint operation. This seems to be too much of a cpu hog.
I wish I had a more firm grip on trigonomerty so the points could be scaled along the rotational axis.
My code this week has no errors. But it's Monday morning and I haven't got out of bed.
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Hi,
if you don't want to store and re-apply the transformation matrices on every paint or mouse action, you will have to store actual coordinates in the derived class, and modify those when you apply a new transformation. The logic required to transform a single point can still be implemented once in the base class, and used in the derived classes as often as is required.
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If its a CPU hog, consider buffering or picking a framework like Piccolo or WPF which takes care of most of the details for you.
An affine transform matrix can almost be seen as a cache of how the input vertex relates to the output vertex. I would expect that performing the actual trig operation on every vertex would be quite slow indeed.
Take a look at the graphics primer that the Piccolo project provides, you'll probably find it fairly helpful.
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Why don't you just inverse rotate the mouse movement?
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Hi,
I am creating a generic custom controls (for instance, say button) using OpenGL for drawing. So what I did is, created a window and initialized the OpenGL with window handle and DC. And drawn something to OpenGL context and so on.
So when multiple instance of my control is used, the OpenGL context will be created for each (control) window.
My question is that, creating many OpenGL contexts (with wglCreateContext) is having problems of any kind?
Thank you.
- ns -
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I have some images in an old non-standard file format that I'd like to display into the MDI window of my new app. I've got the image read in from the file and MFC is making the correct size window for it but how do I blt the array to the window?
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I'm fairly sure that there is no existing MFC function that will do this easily. But, if you want to use the BitBlt[^] GDI function to display your array, it must be in the native windows bitmap format. I have no idea what your "old non-standard file format" is like. But, if you can read the existing pixel data into a continuous linear array, with a bit depth that is equivalent to one of the standard bitmap bitsperpixel values (16, 24, or 32 bpp), and write the headers yourself, it should work. You should read this: Bitmap Header Types[^].
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Hey I just got it working, thank God! I've been using the CImage class to load in all the other types of images and I just do a CImage::Create to setup a bitmap with the correct dimensions and bpp, and then call SetPixel to load each pixel into the bitmap. It works! Maybe a little slow for some larger images but it works. I tried this before w/o the Create call and it didn't work, so that was the key.
There might be a faster way so if you think of one let me know.
Thanks,
Darryl
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Hi
I wanna just save changed images in an AVI file,
I want to write a mothen detection for direct show capture,
Where i can find a sample?
Thanks
www.logicsims.ir
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I would like to check the following idea having problems or not... 
1. Initiates openGL with double buffer enabled
2. Render something to back buffer and call SwapBuffers.
3. Render the same again. (To fill the other buffer)
4. Called SwapBuffers only for handling WM_PAINT. That is, no repeated rendering since there is no change in what to draw.
So the point is that, rendering is done when needed to modify the drawing. But whenever repainting is needed the buffer is just swapped to retain the painting. I checked the same and its working fine. But rendering need to be done two times to update both front and back buffers.
Is this way OK? If so how can I avoid the rendering two times?
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No need to render twice, render once and copy.
glReadBuffer(GL_BACK);
glDrawBuffer(GL_FRONT);
glCopyPixels(GL_COLOR);
glReadBuffer(GL_FRONT);
glDrawBuffer(GL_BACK);
glCopyPixels(GL_COLOR);
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Thank you very much... I am just entering to the world of openGL
Could you please tell me that the idea of doing SwapBuffer only, in response to WM_PAINT, is good? Is there any problem in that? Or is there any better solution?
Thank you.
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Matters on what you are trying to do, you don't need to use wm_paint at all, you can update the render whenever you feel you need to.
If you need to continually update the window, u can use a pump, ie:
bool quit = false;
while(!quit) {
PeekMessage(&msg, hwnd, NULL, NULL, PM_REMOVE);
if (msg.message == WM_QUIT) {
quit = true;
} else {
DoRendering();
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
Or you can simply swap buffers when u only render, not on every paint.
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Thank you for the reply. I got it.
Actually I don't need to update the rendering continuously. That's why I decided to move the SwapBuffers to wm_paint. Drawing need to be updated only at some events say mouse click, etc.
- ns -
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Now got another problem... if we lock windows and then unlock the drawing in the buffers are lost...
What should be done to handle windows lock/unlock conditions?
Thank you.
- ns -
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I get the feeling that the best approach for you is to use a FBO and do offscreen rendering.
Google "opengl render to texture", you can bind a frame buffer at the start of your rendering, then blit it as needed.
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Thank you very much. I shall try for that.
- ns -
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