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Construct a DC from the CPaintDC, and use DrawText of gdi function to draw on the screen...
Cheers
Regards.
The World is getting smaller and so are the people.
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The simple way:
Load the bitmap into a CBitmap. Get it's dimensions and construct a target-compatible, memory-based DC. As an example, create a DC based on the device context of the window you wish to display the bitmap in.
Then select the CBitmap into the memory-based DC, use the TextOut function to write a string of text to it. Now you can use the BitBlt function to copy bits from the in-memory DC (containing the bitmap and the text) to the window display DC (most apparently blank).
See the MSDN for CDC:CreateCompatibleDC for an example, which loads a bitmap from a resource file, then spanks it to a window. The idea behind everything is that when you "select" a bitmap to a DC, the DC will represent the drawing surface of this bitmap.
For a more in-depth explanation and tutorials, see Chris Becke's tutorial Bitmap Basics - A GDI tutorial[^]
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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Antti Keskinen wrote:
create a DC based on the device context of the window you wish to display the bitmap in.
Actually that bmp is not fixed on a particular window..
Basically its a dragImage.It moves along with the mouse pointer...
So will ur solution work for this case?
cheers,
Super
------------------------------------------
Too much of good is bad,mix some evil in it
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You mean that you drag the image around with the mouse, much like in a rectangle-cut method used in many paint applications ?
I've gotta hand it out, though, I can't help you on that one without doing some extensive research first. Perhaps someone else can help you out.
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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hi friends!
I am very much willing to make chat software that can allow the people to chat within a lan. i also want to add the sound and web cam part to it(but at a later stage). just like another yahoo messenger but for a lan.
i have read a lot abt TCP\IP. and am not able to decide frm where to start.
if somebody can help me out in this context i'll be very gr8ful.
might be that we can work together to achieve something new.
pls mail me at : deepeshdhakad@rediff.com
Deepesh Dhakad
Indian Institute of Information Technology,Allahabad
India
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http://ring.csi.ad.jp/archives/pc/forest/i/ipmsg/
For writing a chat system you need to have a chat server and client.
I guess you wount be allowed to install your chat server on the server,
instead you can use UDP based chat programs like ipmsg,
download the ipmsg src you will find most of ur needs for writing a chat client on the lan,
but it does not have webcam and sound features in it.
regards,
Prakash.
The World is getting smaller and so are the people.
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.
modified on Tuesday, August 9, 2011 4:47 AM
modified 1-Dec-11 1:45am.
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I dont know about putting image ont he button face, but i guess its not all that difficult if you handle the onpaint event of the button or ondrawitem.
for ur second question, you need to rearrange the item size on the dialog box dynamically , so you need to find the resolution of the screen. You can find out using the win32 api GetSystemMetrics()
cheers
Prakash.
The World is getting smaller and so are the people.
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Actually I have the screen resolution and have calculated the size to which I have to change the button dimensions. Now I am searching for the right API to change the size of the button and also a way to change the size of a bitmap image.
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You can use SetWindowPos to change the size of the button.
And Drawing the image, well you have to strech the image according to the button size , you can do that by using bitblt of gdi.
The World is getting smaller and so are the people.
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Is there any way in VC++, which dumps a folder with contents into a target path (like CopyFile method)
Thanks in advance
Warm Regards,
KKR
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Check out SHFileOperation win32 api, windows explorer does almost everything using this api.
regards,
prakash.
The World is getting smaller and so are the people.
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Thanks Prakash
Its intresting and I will go through it.
Warm Regards,
KKR
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Is it possible to send windows events from one application to another?
To be more specific I want one application to make the other application believe that the user just clicked its "ok" or "cancel" button eventhough the mouse didn't move at all.
The problem is that the two applications can't communicate with each other via any IPC etc. Can we make use of windows hooks here? If so how?
Any ideas or comments would be greatly appreciated.
Thanks
Regards,
Zahid
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Try using DDE or register a custom event with unique ID,
then broadcast the message from one application to all the windows.
only your other application will then process it.
regards,
Prakash.
The World is getting smaller and so are the people.
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Generally, in a dialog-based application, the Ok button has an ID IDOK attached to it. CDialog class has a default handler for a click of this button.
If the application in question has this handler implemented or overwritten, you can simulate the clicks of the default Ok and Cancel buttons by sending a WM_COMMAND message. The default identifiers, which MFC recognizes, are IDOK and IDCANCEL. See WM_COMMAND reference for details.
The other method (MFC style) would be to access the dialog window through a HWDN and FromHandle method of CDialog. Then use UpdateData and PostQuitMessage member methods to terminate the dialog window, or alternatively call the default OnOK handler, which does the same things.
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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I liked your idea very much but the problem is that I want it work for other buttons on the Dialog as well that I don't know the ID for. Infact I don't have access to the source code of the target application whose buttons I want to press. So I can't write any handlers in there.
Secondly I tried simulating a mouse click by doing
mouse_event(MOUSEEVENTF_LEFTDOWN, 50, 50, 0, 0);
mouse_event(MOUSEEVENTF_LEFTUP, 50, 50, 0, 0);
which kind of works but sends messages to the self application and not the target one (since the x,y coordinates are relative to the current window).
Back to the send WM_COMMAND message you talked about? What kind of message do I need to send inorder to simulate a mouse click. Since I don't know what the names of the Messages the target application handles in its code I probably can't send it Button_Click messages, so it has to be mouse_click and also how do I determine the 1st hWnd argument....right now I am doing a broadcast? Thanks.
Regards,
Zahid
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According to the Platform SDK Reference, when a button is clicked, it will send a BN_CLICKED notification to it's parent. This notification is packed to a WM_COMMAND message.
In order to simulate a mouse click, you must send WM_LBUTTONDOWN or WM_RBUTTONDOWN, depending which mouse button you'd like to simulate. These messages carry with them position information in a POINT structure. The structure's coordinates are relative to the target window's upper-left corner.
However, the mouse message must be sent to the button window, which then sends a BN_CLICKED message to it's parent. If you do not have access the source code at all, then one option is to create an enumeration function to enumerate through all the child windows of a dialog.
Buttons are, in fact, standard windows with a class name of "Button", if they are default buttons. When doing the enumeration, you can compare the class name of the window and it's caption to determine the correct button. Say, a button which reads 'Click me', would have a class name of "Button" and a window text of "Click me".
The enumeration could be implemented by using a while-loop in accordance with a GetNextWindow function call. Here's a half-pseudo code on how to implement it:
CWnd* pChildWnd = dlgPointer->GetTopWindow();<DIV>
while (true)
{
TCHAR buffer[40];
CString strCaption = "";<DIV>
::GetClassName(pChildWnd->m_hWnd, (LPTSTR) &buffer[0], 39)
pChildWnd->GetWindowText(strCaption);<DIV>
if ( strstr(buffer, "Button") && strCaption.Find("Click me") != -1 )
{
break;
}<DIV>
pChildWnd = pChildWnd->GetNextWindow();<DIV>
if ( pChildWnd == NULL )
break;<DIV>
}
After obtaining the CWnd pointer of the desired button window, use CWnd::SendMessage to post a WM_LBUTTONDOWN message to the button. It will then respond by posting the BN_CLICKED message to it's parent.
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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Thanks for detailed reply Antti. It worked!! I had to implement the whole thing in WIN32 API since the SendMessage took only 3 parameters in MFC and not the window pointer. Also I used WM_LBUTTONDOWN followed by WM_LBUTTONUP to simulate a mouse click.
Regards,
Zahid
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Sir i want to creat a Vc++ system wide hook dll.{{Whatever hook articles available on the internet are intended for advanced developers who know thing or 2 in vc++.}}But students like me who are new to vc++ find it difficult to grasp some ideas.
I want a basic level explanation from some experts who really wants to teach those things to their students.
The hooks i am intended to create is Wh_Getmessage and i have to call that dll from vb6
Say my objective of this hook is say if i a user type A then i have to change to B for any application running.
I am a stranger to vc++ so i need help in how to create this {{system wide}} wh_getmessge hook
1.In vc++ in new what dll i have to chose ]
a.MFC appwizard Dll
b.WIn32 Dynamic link library
What is the difference between these 2 dlls.?
2.What is an header file and what are the things we have to declare here and why we have to declare??
3.How functions in vc++ dll should be declared inorder to call those functions from vb.?
4.Say i am calling SetHook funciton from vb which is in dll then hook is set.
MsgFilterHook = SetWindowsHookEx( WH_GETMESSAGE,(HOOKPROC)MsgFilterFunc, dll_hInstance, threadID );
I am having the hookhandle in MsgFilterHook which i can use to unhook this hook.
Threadid = 0 to create a system wide hook
MsgFilterFunc is my callback function
My doubt is once hook is set , will the system automatically call my callback filter function for any application which process getmessage
Say i have notepad and i am typing A and in my call back function i will get a wm_char = A.NOw if i change to another application say wordpad and type B
then will it be possible to get the wm_char=B message in my callback function.Please Explain me how does this work.
5.Say n no of editor applications are running and i want to disable the character T from going to any application and i have to make T into H how to do this in my callbackfunciton.Issue in this question is how am going to get these hook work for any application which is running.??
Issues
1.How to start creating a dll in vc++6
2.Header file decleration ideas.
3.Export functions declerations.
4.Explanations of how these hook work on a systemwide basis(i understood how dll maps the memory of other applications but wanted codings point of view like what are the parameters come to callback function each time a new application is actvated.)
5.What is #pragma and shared data segment ?How variables should be decalred in the hook dll and how it should be accessed??Please explain at a lower level how this things are implemented why is the need?
Thanks in advance.
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First, I recommend pointing your browser to MSDN and the Win32 Hooks article[^] underneath it. Read it through carefully, because it will answer most of your questions.
If you don't understand the concepts presented in this article, then you should learn more of the functionality of Windows before attempting to create hooks. Codeproject has a collection of fine articles on the issue of hooking. These should help you get started.
Now, about using the hook. Basically, you can create the DLL on any language you please. If it is implemented correctly, you can load the DLL in VB and use a VB program to register the system wide hook. Remember here, that the actual DLL is a container, with which the hook procedure is injected to a foreign process' address space. The loader application is responsible for actually registering the hook.
As for the questions you presented, here is a set of answers.
1. For creating the container DLL, take Win32 Dynamic Link Library project.
2. The creation of a DLL is explained throughoutly in many articles here in CodeProject. Just browse, and look for articles with the level 'Beginner' marked next to them.
3. In order to call a function of a DLL from the loading application, you need to EXPORT it. See the DLL articles for examples. In short, use __declspec(dllexport) calling convention and a module definition file's EXPORTS section.
4. When you register a global hook, your DLL gets cramped into every running process' address space, and the hook is installed to the message pump of every thread on that process. So, yes, all WM_GETMESSAGE call returns will be routed through your hook procedure.
The way it works is that the hook will be the first to receive the created event message. You then process this message, and alter it the way you please, for example in a WM_CHAR message, you would change the virtual key code. Then you post the message forward in the chain list, and it will eventually end up to the thread it was meant for, this time in an altered form.
5. Like above, catch the WM_GETMESSAGE return value, see if it is a WM_CHAR message, and if it is, alter the virtual key code. If you register the hook correctly, the system will worry about it getting properly called.
For the issue questions
1. Select the appropiate project, and implement the DLL code, following any of the many articles available. There are even beginner articles available in CodeProject. If you cannot understand the concepts of these, you should go pick up a book and learn more about Win32 applications first.
2. The header file is not necessary. A DLL MUST have a DllMain-function (entry point) and one or more exported functions or shared data segments. Otherwise it is just extra baggage with nothing useful.
3. To declare an exported function, use __declspec(dllexport) calling convention or a module definition file. See MSDN, search with the __declspec keyword.
4. The hook's working is explained in the MSDN article I posted a link to above. Refer to it for more details.
5. #pragma is a preprocessor definition which can be used to issue commands to the MSVC compiler. In a standard hook DLL, you don't need shared data sections, thus, you don't need #pragma.
When answering, please take some time to formulate and type-check your posts. It is much more convinient to read and answer your questions when they are easy to understand and the points you're after are presented clearly. Use chapters, line changes, spaces, punctuation marks, everything you need to make it easier to read 
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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Thank you very much sir for your Excellent explanations.
I have catagorised my doubts below .Could you help me on that.
Dll Main:
dll_hInstance
HINSTANCE dll_hInstance;
BOOL WINAPI DllMain( HINSTANCE hInstance, DWORD dwReason, LPVOID lpVoid )
{
dll_hInstance = hInstance;
return TRUE;
}
SetWindowsHookEx( WH_GETMESSAGE, (HOOKPROC)MsgFilterFunc, dll_hInstance, threadID );
}
In this example i am getting hinstance of the dll from DllMain.
1.Is Dll main function to be called from my application or this function is executed automatically.?
2.if it is to be called from my application then what are the parameters i have to send?
3.What is the significance of this hinstance to be passed to SetWindowsHookEx function as one of the parameter.
in a system wide hook?
4.I have declared this dll_hInstance as global variable and whenever an application get mapped with this dll , is function Dllmain triggers? and do dll_hInstance get initialised?
Comment: in some article they have given ,declaring dllmain is optional and some they have just declared and so i dont get the idea
behind what is the purpose of this dll main and when doing a global hook what is the significance of dll hinstance.?In some article They have given like
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
hinstance = (HINSTANCE)hModule;
hook = NULL;
return TRUE;
}
I couldnt track from the application how this function is called.So i need your help in this topic
___________________________________________________________________________________________________________________________________
HeaderFile For Dll:
Here is an example header file for a DLL:
#ifndef __DLL_H_
#define __DLL_H_
#ifdef MAKE_A_DLL
#define LINKDLL __declspec( dllexport)
#else
#define LINKDLL __declspec( dllimport)
#endif
LINKDLL LRESULT CALLBACK MsgFilterFunc (int nCode, WPARAM wParam, LPARAM lParam );
LINKDLL void SetHook( HWND hWnd, HHOOK &MsgFilterHook );
LINKDLL void RemoveHook( HHOOK &MsgFilterHook );
#endif
In this example:
#define LINKDLL __declspec( dllexport) is given .
1.Is defining like this enable us to use or call these functions from our application.? Could you explain what is the meaning of defining like this?
2.Sir you have suggested that an header file is not necessary then could you give me some ideas how i can declare those functions using declspec( dllexport) and what file i have to add like header file or def file or in dll iteself or ......?
Inclusion of HeaderFiles in Dll:
#include <windows.h>
#include <windowsx.h>
#include "stdafx.h"
1.While creating a dll and in my case it is wh_getmessage hook dll what are the header files i have to include and what is the purpose of including #include "stdafx.h"
2.Is all the header files added in dll should be declared in my application also if i am building my application in vb?
Processing in Filter Funcion:
LRESULT CALLBACK MsgFilterFunc (int nCode, WPARAM wParam, LPARAM lParam )
{
MSG* Msg = (MSG*)lParam;
switch( Msg->message )
{
case WM_COMMAND:
break;
case WM_KEYDOWN:
break;
case wm_Char
--------------------------Processing------------------------------------
}
return( (int)CallNextHookEx(NULL, nCode, wParam, lParam ) );
}
The nCode parameter is a hook code that the hook procedure uses to determine the action to perform
if (nCode < 0) // do not process message return CallNextHookEx(myhookdata[GETMESSAGE].hhook, nCode, wParam, lParam);
1.What are the situations where we have to call CallNextHookEx and what actually happens in calling CallNextHookEx?
2.Say we process the wm_char message and still we have to send the control to CallNextHookEx , after processing this command?
Thanks in advance
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I'll answer your questions likewise.
DllMain
-------
1.DllMain is the entry point function of the DLL application. When you use LoadLibrary or AfxLoadLibrary to load the DLL into a process, this entry point is used to start the execution of the DLL. It is much like a 'main' function for a normal C++ application.
2. No parameters necessary, it is called automatically and Windows will provide the parameters.
3. The instance you pass to SetWindowsHookEx tells the function the name of the module where the hook filter function resides. You get this instance handle from a call to LoadLibrary or AfxLoadLibrary, as it's return value.
4. You've got it somewhat incorrect: you do not need to save the instance handle of the DLL in DllMain. Once more: when you want to create a global hook, you create two applications. The first app is a DLL, which exports the hook filter function. The second is a loader application which loads the DLL, obtains a pointer to the filter function and calls SetWindowsHookEx with these parameters.
You can use your custom implementation of DllMain to keep a reference or loading count, for example. Like, for the first time your DLL is loaded (by the loader app), you save the handle of the loader application. Then, your loader app registers a global hook, and the DLL keeps score to how many processes it is attached to (including the loader app). When this score reaches zero, the DLL can, for example, signal the loader application that it can unregister the hook and unload the application.
But it's good policy to implement it, even if you didn't do anything else there than just return TRUE.
Headerfile for DLL
------------------
1. In order for a function to be available for external applications, it must be exported from the application. This is more common with DLLs than with EXEs, although possible in both. You can define a function exportable by adding the __declspec(dllexport) into it's calling convention. For example, the following would cause the function 'ExportedFunc' to become available to loading applications
__declspec void ExportedFunc(void);
Using this, however, requires that you add the function name and a free ordinal to the module definition file, like
EXPORTS
ExportedFunc @1
The ordinal number can be any integer from 1 to X, where X is the amount of functions you wish to export.
In the calling application, you would require to declare a pointer-to-function type, then use GetProcAddress to get the address of the exported function. For example, the following typedef would create a new type, which is "a pointer to a function returning void and taking no parameters"
typedef void (*TypeName)(void);
Creating a variable of this type would then be
TypeName MyFunc = (TypeName) GetProcAddress(...);
2. See above. In order to succesfully and safely export functions from a DLL, use both the __declspec calling convention and a module definition file entry. When you create a new Win32 DLL project using the App Wizard, a module definition file is created for you. Just add the function name precisely as it's name is defined in the .cpp file into the EXPORTS section.
3. The stdafx.h file is created by the App Wizard. In order to build Windows applications, certain common headers (like >windows.h<) are required. The stdafx.h and stdafx.cpp are just dummy files to include common header files.
4. No. If you use __declspec and the EXPORTS section entry, you do not need to include the header files to any applications beside the actual DLL.
Processing in filter function
-----------------------------
1. You should always call the CallNextHookEx. This function is used to pass the message forwards in the hook chain. If you wish to intercept a message, that is, you do not want the message to reach it's intended target, then you don't need to call the next hook. HOWEVER, if you install a system-wide hook, you MUST CALL the next hook, otherwise your computer will hang, as no messages are getting through. In that case, Windows will appear frozen, and the only way to remedy that is a reboot.
If the nCode value is smaller than zero, then you must call the next hook instantly, without doing any processing for the message.
Calling the next hook causes the next hook in the hook chain to get a chance to process the message. If there's only one hook (your global hook) beside the standard message handler of an application, this would mean that you pass the message to this handler, and the application which you hooked behaves like it is meant to behave.
2. Hook procedures are mainly used for modifying a message's contents. You can always skip calling the next hook, but like said, this might result in system-wide crash or errorneous functionality. Windows OS is designed to be event-driven: when you click a mouse button on a window, a message is sent to that window. If you use a message hook to intercept and dispose of the message before it reaches it's target, the window (and it's application) are never notified of the mouse click, and respectfully, do nothing as a result.
Think of this like trying to move your mouse, but the cursor wouldn't budge. Someone might've hooked and is silently disposing of all your WM_MOUSEMOVE messages to the desktop window. So, the desktop will never be notified that you have moved the mouse, no matter how much you'd wiggle it. From a user point of view, this is the most frustrating behaviour Windows can offer, so be very careful when creating your hooks...
I wrote a small workspace containing two projects, a DLL and a Loader. The DLL contains a system-wide WH_GETMESSAGE hook, and the loader is used to load it. The DLL is made with the Win32 DLL wizard, and the loader is a standard dialog-based MFC application. You can download the zip-file from here[^]
Read the comments carefully in the code, perhaps they help you out. Feel free to use the application as a base to build your own solution upon. It is made with Visual Studio .NET 2003, so if you don't have it, just use Notepad or something to explore the files 
You can test the app by running the MFC application found from Hookinh/HookLoader/Debug directory.
-Antti Keskinen
----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.
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Hello Thank you very much sir for the dll.
Now i have created the system wide hook dll using your dll as base.
So no problem in that and it work beautifully well.
The problem now i have is i have tried so many methods to find which character is pressed in wmChar
but i dont find any way to get that char for checking it
if ( msg->message == WM_CHAR )
{
It dont work for both funcitons
//if ( WM_CHAR=='A' )
//{ MessageBox(NULL,"A","TEST",MB_OK); }
UINT nchar = lParam;
if ( nchar=='A' )
{ MessageBox(NULL,"A","TEST",MB_OK); }
}
Sir Could you help
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