I'm creating a plugin framework, where my application loads a series of plugin DLL's, then creates a new window and pass this new window's handle to the plugin. The plugin can, then, use this handle to create their own GUI.
Everything seems to be working very well. The only problem is that when I press TAB on a plugin widget (An editbox, for example), it doen't jump to another widget. I figured out that some Windows messages are passed, and some others aren't. The WM_KEYDOWN is passed for other keys, because I can type on the editbox, but this message doesn't handle TAB key.
Hope somebody has a hint.
I'm using Borland VCL with CBuilder, but I think I could use any framework under WIN32 to create these plugins, since they never know how their parent windows were created.
It's very complex matter indeed.
When you hit TAB focus jumps to another control only when these controls belong to a Modal Dialog Box. In fact there are some buttons like ESC, LEFT, RIGHT, DOWN, UP, TAB which modal dialog message function treats in a special way. If you want these keys to behave in similar way with modeless dialog box or any other window you should change you message processing function and use IsDialogMessage inside. You'll find more information about IsDialogMessage function in MSDN also to better understand this stuff you may check as well Dialog Boxes section.
And, as was mentioned before, you should set WS_TABSTOP and WS_GROUP styles when needed.
Good luck!
I believe you'll have to take the following steps:
Subclass your edit controls (and other controls as needed).
Capture the WM_KEYDOWN message in your edit control's WndProc.
Check to see if the shift key is currently held down (using GetKeyState or similar).
Call GetWindow, passing in a handle to your edit control and either GW_HWNDPREV or GW_HWNDNEXT depending on whether shift is held down. This will give you the handle to the window that should receive focus.
Call SetFocus and pass in the window handle you got in step 4.
Make sure you handle the case where your edit controls are multiline, as you might want to have a real tab character appear instead of moving to the next control.
Hope that helps!
I believe you suffer from having a different instance of the VCL in each of your dlls and exes. Classes from the dll are not the same as the ones from your exe, even if they are called the same. Also global variables (Application, Screen) are not shared between them. Neither is the memory since they both have their own memory manager.
The solution is to have the dlls and the exe share the VCL library and the memory manager. I am not a BCB developer, but a Delphi developer. In Delphi we would just use the rtl and the vcl as runtime packages. Maybe you could do the BCB equivalent.
A DLL has its own TApplication object.
to provide uniform key handling. when the DLL Loads.
assign the DLL::TApplication to the EXE::TApplication
Be sure to do the reverse on exit.
--
Michael
Related
I've been trying to create a MessageBox with changeable, readable text and customizable buttons, I think making a hook for it would probably be easy for this but I read at MSDN:
"Hooks tend to slow down the system because they increase the amount of processing the system must perform for each message. You should install a hook only when necessary, and remove it as soon as possible."
I'm wondering whether it's really worth it when I can just use CreateWindowEx to make an imitation MessageBox that does all I want. How much do hooks really slow the system down, is it worth it or should I be going with CreateWindowEx instead?
Depending on your target systems, have you considered using one of the new message boxes (Task Dialogs) available starting with Windows Vista?
These allow you to customize the dialog layout of the box with custom buttons, etc. without requiring any hooks or custom windows (as in "create from scratch").
Otherwise I'd probably go with the hooks (you only need them to catch your box, so you could setup them before showing the box, and removing them once you've been successful).
I have an app with a customized frame (i.e., caption/titlebar, borders). I customized the frame by removing the WS_CAPTION style, and overriding OnNcCalcSize to reserve a custom-sized area for the caption, which the app paints in OnNcPaint.
A side effect is that the menu bar no longer displays, which is OK because I want to customize the appearance & location of the main menu. Unfortunately, I don't know how to do that. I would like the "File" menu to be further from the left edge than it is with the standard menu bar.
An acceptable alternative would be to remove the menu entirely, and use OnNcHitTest, OnNcPaint and OnNcMouseMove to manage a hand-coded replacement for the top-level menu.
I've never seen a way to modify the looks of the standard menu. You can remove it (remove the creation code from your InitInstance) and then code a replacement. I wouldn't do that in OnNcXXX though, rather make a new custom control that you position at the top. Or you could have a look at the MFC Next themed menus and write a custom UI renderer. It may be enough to override a few functions left and ride to set the alignment of the menu.
It's an MFC MDI app -- InitInstance is not where the menu is being created. I have tried to get rid of the menu (and succeeded, temporarily) but the MFC framework seems to be "putting it back" -- I think the MDI model has the child windows modify the menu, but the code that does that seems to be buried in the framework somewhere (or else I just haven't been able to find exactly where it happens in the application's code, but I suspect it's happening inside the MFC framework code). If I knew where, I might be able to override the methods(s) and take control... I think.
What would be the reason to write a custom control vs. handling OnNcMouseMove & OnNcLeftButtonDown, e.g.? I don't expect to need the functionality in any other app (a new app would be coded in C#, probably), so I'm looking for ease of implementation, not code reuse.
I have a dynamically created toolbar on a plain Win32 dialog. My buttons are added with & shortcuts which correctly puts underscore to characters following ampersand but pressing Alt+(char) causes a beep and the button is not clicked.
It has been a while since I have done Win32 API development. Is there something that needs to be done to a dynamically created child window (toolbar) in order for the accelerator keys to work?
This could be something really obvious that I am missing...
Well... You have to write code to handle these keypresses and convert them into WM_COMMAND messages. The traditional way to do this is to define an accelerator table and process them using TranslateAccelerator() - but of course, you're free to do it however you like... Just make sure the keys you handle jibe with the keys you underline!
You might also find this KB article helpful: How to use accelerator keys within a modal dialog box in Visual C++... Or, for a more in-depth (and MFC-free) look at implementing custom message processing in dialogs, check out Raymond Chen's articles on the dialog manager, specifically part 4: The dialog loop and part 9: Custom accelerators in dialog boxes (but seriously, read the whole thing, you know you want to...)
The beep indicates that the command isn't handled by any window in your app.
Since you created the toolbar dynamically, I would guess that the toolbar window isn't set up properly as a child window of your main window (i.e., it's parent and owner window are not set).
To test: click on the toolbar so it has the focus, then press Alt- and it should work.
I want to make a C++ button on Start>Run i.e but when I do it will not do signalled event?
Im sorry I have seen that you do not get the question.
Ok basically when you create a button with CreateWindowEx(); I want to do that but put on a different window with SetPArent which I have already done now the button does not work so I need my program to someone get when it is clicked from the Run window as example!
And yes you have it, but it's not making the button is the problem it's getting when it's clicked with my program since it does not belong to it anymore!
You need to apply the ancient but still-supported technique known in Windows as subclassing; it is well explained here (15-years-old article, but still quite valid;-). As this article puts it,
Subclassing is a technique that allows
an application to intercept messages
destined for another window. An
application can augment, monitor, or
modify the default behavior of a
window by intercepting messages meant
for another window.
You'll want "instance subclassing", since you're interested only in a single window (either your new button, or, the one you've SetParented your new button to); if you decide to subclass a window belonging to another process, you'll also need to use the injection techniques explained in the article, such as, injecting your DLL into system processes and watching over events with a WH_CBT hook, and the like. But I think you could keep the button in your own process even though you're SetParenting it to a window belonging to a different process, in which case you can do your instance subclassing entirely within your own process, which is much simpler if feasible.
"Superclassing" is an alternative to "subclassing", also explained in the article, but doesn't seem to offer that many advantages when compared to instance subclassing (though it may compared with global subclassing... but, that's not what you need here anyway).
You'll find other interesting articles on such topics here, here, and here (developing a big, rich C++ library for subclassing -- but, also showing a simpler approach based on hooks which you might prefer). Each article has a pretty difference stance and code examples, so I think that having many to look at may help you find the right mindset and code for your specific needs!
OK, I'll do my very best - as I understand you, you're trying to inject a button into some existing window. That meaning: Your tool creates a button in some window that does not belong to your application. Now, you want to be notified when that button is pressed. Am I correct so far?
To be notified about the button being pressed, you need to get the respective window message, which will only work if you also "inject" a different WndProc into the window. Actually I have no idea how that should work, but I faintly remember functions like GetWindowLong and SetWindowLong. Maybe they will help?
EDIT
I've searched MSDN a little: While you can get the address of a window's WndProc using GetWindowLong, you can not set the WndProc using SetWindowLong on Windows NT/2000/XP (and up I suppose). See here (MSDN).
So what you could do is install a global message hook that intercepts all window messages, filter those for the window you've injected the button into and then find your message. If you have trouble with this, however, I'm the wrong person to ask, because it's been years ago since I've done anything like that, but it would be stuff for a new question.
EDIT 2
Please see Alex Martinellis answer for how to define the hook. I think he's describing the technique I was referring to when I talked about defining global message hooks to intercept the window messages for the window you injected your button into.
I need to know when my Window goes out of input focus, so I overloaded the OnKillFocus() method of the CWnd.
However it doesn't invoke this method when I focus another application (alt+tab), or even minimize the window. But it DOES invoke the method when I restore it from being minimized. Are these the intended times for it to trigger this method?
I think you'll need a CWnd::OnActivateApp() handler if you need to be sure of being notified when your application is switched out.
OnKillFocus() is normally only used consistently for controls that have a concept of gaining the focus - buttons, edit boxes, list boxes, etc. Normally CWnd does not accept the focus, so you can't rely on that - I'm surprised you get it at all.
In addition to WM_ACTIVATEAPP mentioned above, there's also WM_ACTIVATE when switching between windows within the same application you might want to trap.