Re: Windows Hook - C / C++ / MFC Discussion Boards

giannibal20-Dec-04 9:49

20-Dec-04 9:49

I'm trying to print an image with DrawImage (GDI+ library).

graphics.DrawImage(pImage, rfDraw, rfPic.X, rfPic.Y, rfPic.Width, rfPic.Height, UnitPixel);

The graphics object is constructed with a printer device context.

The <rect>rfPic rectangle is the source area to draw from, e.g. (0, 0, 1000, 800) pixels. The rfDraw rectangle is the destination area to draw to, e.g. (100, 100, 6100, 4900) pixels. On a 600 x 600 dpi printer, this should result in a 10 x 8 inch image.

However, the image is blown up to gigantic proportions, so I only see a small magnified portion of the image. Can someone tell me why?

Drawing to screen works fine (same code, different values). I tried other unit values, setting the page scale and a lot of other things. No luck.

Can someone help me please?

Thanks,
giannibal

Help me with image displaying solutions

Budric B.20-Dec-04 7:44

Budric B.

20-Dec-04 7:44

Hi,
I have a pointer to some raw pixel data and I'd like to display it to the screen and then allow the user to click on a point and get the image's pixel coordinates of the mouse click. Also because the images are big I'd like to have a scroll bar so that you can show a 1:1 image in a smaller window. Also ideally i'd like the window doing this to be a dialog in modal mode.

I can use the WM_PAINT message with SetDIBitesToDevice(...) in WM_PAINT of a dialog box to solve some of those problems, however then I don't get the scroll bars. I tried creating my own control from:
http://www.codeproject.com/miscctrl/customcontrol.asp[^]
tutorial, but it's not going too well and I realized that implementing my own scroll bars will be hard.

Any help is appreciated.

Also...

Budric B.20-Dec-04 7:49

Budric B.

20-Dec-04 7:49

Just remembered,
I was having trouble displaying a 8 bit grayscale image with SetDIBitsToDevice. What constant for the compression parameter can I use?
Here's the reference http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdi/bitmaps_1rw2.asp[^]

Re: Also...

Christian Graus20-Dec-04 9:45

Christian Graus

20-Dec-04 9:45

There is no compression on an 8 bit image, but it is paletized. Do you have a palette in your data ? If not, then that will be the problem. Can you do other 8 bit or less images OK ?

Christian

I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer

Re: Help me with image displaying solutions

Christian Graus20-Dec-04 9:43

Christian Graus

20-Dec-04 9:43

Turn your bits into a DIBSection, then just draw that to the screen in WM_PAINT, taking into account the positions of the scroll bars.

also take the scroll positions into account when a user clicks.

Christian

I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer

Re: Help me with image displaying solutions

Budric B.20-Dec-04 10:31

Budric B.

20-Dec-04 10:31

I'm basically trying to output *.ppm and *.pgm files. The file format of ppm is a simple header followed by 24 bits for RGB for each pixel. For the pgm it's a simple header followed by 8 bits per pixel.

I can read and display the ppm files using this bit of code:

<br />
		BITMAPINFO bi ;<br />
		bi.bmiHeader.biSize          = sizeof( BITMAPINFOHEADER );<br />
		bi.bmiHeader.biWidth         = m_nWidth;<br />
		bi.bmiHeader.biHeight        = -m_nHeight; // top-down bitmap, negative height<br />
		bi.bmiHeader.biPlanes        = 1;<br />
		bi.bmiHeader.biBitCount      = 24;<br />
		bi.bmiHeader.biCompression   = BI_RGB;<br />
		bi.bmiHeader.biSizeImage     = ::abs( m_nWidth*m_nHeight ) * 3;<br />
		bi.bmiHeader.biXPelsPerMeter = 100;<br />
		bi.bmiHeader.biYPelsPerMeter = 100;<br />
		bi.bmiHeader.biClrUsed       = 0;<br />
		bi.bmiHeader.biClrImportant  = 0;<br />
<br />
		::SetDIBitsToDevice(<br />
			dc.GetSafeHdc(),<br />
			0, <br />
			0,<br />
			m_nWidth, <br />
			m_nHeight,<br />
			0, <br />
			0,<br />
			0, <br />
			m_nHeight,<br />
			m_pImage, <br />
			&bi, <br />
			DIB_RGB_COLORS );<br />

However this doesn't work for the pgm images. I don't know what header to set or how to display it unless I physically take the data I loaded in the pointer and insert R=G=B=original grayscale data.

Windows Hook

RedDragon2k20-Dec-04 5:13

RedDragon2k

20-Dec-04 5:13

Hi Guys

I want to prevent my app getting terminated by the taskmanager. I saw some examples but they are using dlls that you have to pay for. So I informed myself a bit about that. I figured out that i've to use SetWindowHookEx. And there we are at my first problem: What type of Hook should i use ? i prefered WH_CALLWNDPROC. And how do i have to realize the main loop ? Is it a function that i get with the hook ? I'm never used hooks before, but i'm sure with some help i could do it.

MFG
RedDragon

P.S.: The code will never be used to cause any damage to hard- or software. I'm working on a program which controls pupil pc's.

Unix and C are the ultimate computer viruses.

Re: Windows Hook

Michael Dunn20-Dec-04 7:17

Michael Dunn

20-Dec-04 7:17

You can't, the user is ultimately in control of the computer. If what you want were possible, viruses could do the same thing.
See The arms race between programs and users[^] and Why can't you trap TerminateProcess?[^]

--Mike--
LINKS~! Ericahist | 1ClickPicGrabber | CP SearchBar v2.0.2 | C++ Forum FAQ | You Are Dumb

Re: Windows Hook

RedDragon2k20-Dec-04 7:30

RedDragon2k

20-Dec-04 7:30

Yeah i see. I read this articles, too. But it is POSSIBLE. A programmer already done so. You can find the demo app on: http://www.madexcept.com/ under c++ and then go to MadCodeHook. Yeah you can come with this argument: Why don't you even this code ? Well, how could i get better when i just copy or use dlls from others ?

MFG
RedDragon

P.S: Excuse my bad english

Unix and C are the ultimate computer viruses.

Visit me: www.programming.info.ms

Re: Windows Hook

heman15420-Dec-04 9:27

heman154

20-Dec-04 9:27

If your application is has a window, use classview and add the windows message handler: OnQueryEndSession. In the body, return false, and your application will prevent any shutdown that does not use the EWX_FORCE switch.

Himanshu

Re: Windows Hook

Shog⁹20-Dec-04 12:35

Shog⁹

20-Dec-04 12:35

RedDragon2k wrote:
I'm working on a program which controls pupil pc's.

Have the students using accounts that do not have permission to terminate your process (which can be run under a different account).

Just about anything else is dodgy as hell, and will eventually be broken by any student worth his salt.

"The time has come," the Walrus said, "To talk of many things..."

DoModal returns -1

AnsGe20-Dec-04 4:30

AnsGe

20-Dec-04 4:30

Hai All,

In my application InitInstance method the DoModal() calling of main application dialog return -1(bcoz of some loading problem). but i want to capture it and show some error mesage. But i cann't show any error message or any other dialog when it returns -1.

How i can i solve this problem.

ANyone can have any idea?

regards

Ans

Re: DoModal returns -1

toxcct20-Dec-04 5:47

toxcct

20-Dec-04 5:47

use GetLastError()

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: DoModal returns -1

David Crow20-Dec-04 6:16

David Crow

20-Dec-04 6:16

AnsGe wrote:
But i cann't show any error message or any other dialog when it returns -1.

The reason is most likely here.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: DoModal returns -1

AnsGe20-Dec-04 6:55

AnsGe

20-Dec-04 6:55

Hai,

I tried with ur help. But my problem still remains.
If main window is successfully loaded then it is possible to show any mesagebox. But the main window Domodal() failed then it is not possible to show a MessageBox. The code snip running, but windows are not visible

Thanks

Anish

Re: DoModal returns -1

David Crow20-Dec-04 8:12

David Crow

20-Dec-04 8:12

AnsGe wrote:
...then it is not possible to show a MessageBox.

Did you comment out the m_pMainWnd = &dlg statement in the app's InitInstance() method?

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: DoModal returns -1

Michael Dunn20-Dec-04 7:25

Michael Dunn

20-Dec-04 7:25

Whenever I've had DoModal() return -1 it was due to the dialog using a control whose window class wasn't registered yet. If you're running an older OS and are using any Win 95 common controls, check that you're calling InitCommonControls() in your init code.

--Mike--
LINKS~! Ericahist | 1ClickPicGrabber | CP SearchBar v2.0.2 | C++ Forum FAQ | You Are Dumb

Re: DoModal returns -1

AnsGe20-Dec-04 7:35

AnsGe

20-Dec-04 7:35

hai,

Thanks for ur reply.
i know the exact reason why it retuns -1. bcoz one my ocx is not installed in the machine. But i want to capture the situation and want to display error message.

I have done all hte initialisations in the InitInstance

Thanks

Ans

Checking an ocx is installed or not

AnsGe20-Dec-04 4:21

AnsGe

20-Dec-04 4:21

Hai All,

How can i check an ocx which is droped in my main application dialog is installed or not. I not used the CoCreateInstane function , but i directly placed the control in my dialog. The application crashes when the control is not installed.

How can i avoid it?

Thanks in Advance

Ans

Re: Checking an ocx is installed or not

Blake Miller20-Dec-04 6:11

Blake Miller

20-Dec-04 6:11

You can try the CoCreateInstance before attempting to display the dialog. If that fails, do not show the dialog.

Re: Checking an ocx is installed or not

AnsGe20-Dec-04 6:47

AnsGe

20-Dec-04 6:47

Hai,

Actually i don't know the internal structure about the used COM component. Its a 3rd party control and i have only know some functions in it. I dont know any classid and interface id's.

So how can i call CoCreateInstance()

Byy

Anish

Re: Checking an ocx is installed or not

Blake Miller20-Dec-04 7:05

Blake Miller

20-Dec-04 7:05

Just trying to help here, but maybe you can use this:

HRESULT CLSIDFromProgID(
LPCOLESTR lpszProgID,
LPCLSID pclsid
);

You have to already know what the name of the OCX object is to use the function.

Otherwise, you might need to manually search the registry to find where the OCX is installed, find the OCX, see what it's GUID is, and then try to use the CoCreateInstance.

Re: Checking an ocx is installed or not

naren-vc21-Dec-04 22:32

naren-vc

21-Dec-04 22:32

hi ans,
cocreateinstance is not required to instantiate the activex. i think your problem is u r not included the call to AfxEnableControlContainer(). it ll intializes the framework needed for the activeX container

naren

help: Windows MessageBox prevents custom dialog from showing?

heman15420-Dec-04 3:19

heman154

20-Dec-04 3:19

I have a gui application that is launched via createprocess(...) from another gui application (that subsequently kills itself). This new application creates a secondary thread that creates a dialog (hidden) at thread creation. I am looking for windows shutdown requests on this secondary dialog (using onQueryEndSession()), and then attempt to show this dialog. It works correctly for most cases (e.g. when I press ctrl+alt+delete and then select shutdown), but sometimes I get a "System Settings Change" Message Box which appears after new devices installed. In this scenario, my application catches and prevents the shutdown request, but fails to throw up the dialog when I use ShowWindow(SW_SHOWNORMAL) (by the way, its modeless). Does anyone know why a messagebox like this would cause this behaviour? I found that uninstalling a device brings up a similar messagebox (same caption, different text), but in this test my modeless dialog does appear. Any suggestions would be appreciated.

Thanks,
Himanshu

Alphablend question

__makaveli__20-Dec-04 3:03

__makaveli__

20-Dec-04 3:03

I am using the AlphaBlend function with an image on a transparent window to fade the image in with a timer and an alpha value incrementing from 1 to 255 as the timer fires (I'm redrawing using InvalidateRect), how can I fade the window back out? If I use the same redraw function and decrement the alpha value the images stays the same.

Am I going about it the right way? Is there a way to fade out?

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