Qt is cross platform c++ Gui Library.Code once and compile for different Platform. Let's for instance, I have compiled a Project(decent text editor with few tool bar) or any such program for Windows(x86).
Statement 1: The Program.exe entry point will be WinMain.
Statement 2: The Text editor and tool bar will created using "CreateWindow" win32 api. Qt have its own class to implement but to ask OS(Windows) for creating a tool bar or text editor, Program exe interface with OS(Windows). OS understand what it know it does not know anything about Qt class,so to create tool bar or text editor program have to use win32 api.
Statement 3: All event processing( button click, mouse click) will handles using windows messeging system.
Note: It may seem i am viewing every thing with win32 api glass on my understanding.
Correct. The WinMain implementation is provided by the Qt library.
Half correct. The top-level windows are created using CreateWindow. Child widgets, such as a non-toplevel toolbar are Qt's own widgets and are opaque outside of your application. They are exposed only via the accessibility APIs. This allows you to create more widgets than Windows would be able to deal with. A million child widgets is doable, if not particularly fast.
Correct - there's no other way. Of course Qt immediately translates native messages into QEvent instances and dispatches them internally to various QObject instances. In Qt-land, all events must be received by a QObject instance.
You're incorrect in your assertion that winapi has anything to do with the kernel. Winapi is implemented by a bunch of user-space DLLs. You could implement those DLLs yourself. Those DLLs themselves call into the kernel using the native api. That's the API actually exposed by the kernel to the user space.
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I would like to allow the user to insert a selected text from any source or application into my Qt application using the middle mouse button.
This functionality is already available with the help of the QCliboard class on operating systems with X11 Window System. According to the Qt documentation, this does not work on Windows because Windows does not support the global mouse selection.
Is there a way to make this functionality available in Windows as well? Can this be achieved with a Qt and C++ implementation? Is there possibly a C++ library that I could integrate which offers this functionality?
I have Application A which is a third party Windows application (with GUI) that uses the Qt library.
I want to write Application B which will be responsible for starting Application A. I want Application B to also find buttons on Application B (QWidgets) and send them mouse inputs (click, double click etc).
I can run Application A through using the start function on a QProcess.
How do I do the following from my instance of the QProcess:
Get the top level window(s) for the process
Get a widget by name or (other identifiable attribute)
Get the widgets caption, colour and coordinates (and maybe some other data)
Send mouse move and click events to specific coordinates
Give a widget keyboard focus
Send keyboard key presses
Note - I know how to do this with the Windows API, but asking for a way via Qt. The specific Application A in question does not use the native windowing system, therefore window handles will not show up in Spy++ or Windows API functions.
Update 1 - Cannot seem to get any meaningful objects through the process's children
My attempt at getting child widgets for the process:
QProcess* process = new QProcess();
QString program = "\"C:\\Program Files (x86)\\foo\\bar.exe\"";
process->start(program);
auto widgets = process->findChildren<QWidget*>("", Qt::FindChildrenRecursively);
auto i = widgets.count();
// i = 0
If I find children of type <QObject*> I get 4 results. I used metaObject()->className() to see that I have two pairs of QWindowsPipeReader and QWinOverlappedIoNotifier objects.
Update 2 - Cannot create/inject window from another process
I noticed that when I run the QProcess I can use Windows API functions to get the top level window (top level only). I read in the Qt documentation that you can create a QWindow from the handle of a window in another process using QWindow::fromWinId.
Using this function will throw an 0xC0000005: Access violation reading location 0x00000000. error. I am not passing in a null handle. I am using reinterpret_cast to get the HWND to a WId type. It creates a QWindow only when I create a QApplication beforehand.
The new QWindow will have no children (using window->findChildren<QObject*>("", Qt::FindChildrenRecursively); I assume that the creation of the QWindow does not bring across associated child widgets.
Update 3 - I am currently reading into whether inter-process communication can be used
I have come across various threads, questions and code snippets regarding ICP in Qt. I don't see anything so far that specifically shows that ICP is possible when one of the processes is third party.
I have seen that the Squish Gui test tool lets you interrogate QWidget properties.
This will never work the way you intend it to.
If you really wish to take direct control over the other application, you must inject your code into that application. Let's assume that the application uses a dynamically linked Qt. Then:
Build a binary-compatible version of Qt, using the same compiler that was used to build the application you intend to tweak.
Replace the application's Qt with yours. Everything should still work fine, given that yours should be binary compatible. If not, the binary compatibility isn't there, and you must tweak things until they work.
Edit your Qt to add a hook to initialize your code at the end of QApplication constructor. This makes the Qt module that provides QApplication dependent on your code.
Put your code into a dll that the widgets (for Qt 5) or gui (for Qt 4) module is now dependent on.
Again replace the app's Qt with yours, with hooks that start your code.
Your code will of course need to be asynchronous, and will be monitoring the application's progress by inspecting the qApp->activeWindow(), qApp->allWidgets(), etc.
That's pretty much the only way to do it. You can of course inject your code in any other way you desire, but you will need to work with a binary-compatible version of Qt just to compile your code. Note that binary compatibility encompasses more than merely using the same compiler version and Qt version. Many of the configure switches must be the same, too.
I have a problem. I am using C++ to develop an application in Win32 that among other scopes automatize some user input process in an external app in order for the user to be ready to operate.
Particularly I would like to use Win32 API to fill some text in a Qt QWidget control. I wrote a DLL in pure C to get this task done. I tested it on a MFC application and it works very well.
Anyway I could not get it to work for Qt QWidget controls.
I was able to get the right handle via the EnumChildWindows function (stored in the struct Field).
SendMessage(Field.hFound,WM_SETTEXT,(WPARAM)NULL,(LPARAM)_T("bla bla bla"));
But the SendMessage doesn't seem to work because maybe the control (most probably a QLineedit) supports other messages to get this job done.
Is there any specification for these events, I googled a lot but I could not find anything suitable.
What is the most straightforward way to get this code working? Is there an Event table mapping for Qt I could use? Do I have to use some Qt headers and link it against a DLL (this could be a problem because of licensing)?
Thanks in advance.
Qt, at least 4.8 and 5.x, uses foreign controls. None of the widgets, beyond the window, have native handles. Your EnumChildWindows is most likely not finding what you think it's finding.
If you don't have access to the Qt application's source code, there's nothing else you can do, short of injecting your own code into the running application. If the application is dynamically linked, you can figure out what version of Qt it's using, and what compiler it was compiled with, and the likely set of Qt configuration options. You can then compile your own code with the same compiler and using same Qt version, and inject it into the running application. You can then enumerate visible windows, and their children, and find the control you're after.
In our project we have three independent applications, and we have to develop a QT control application that controls these three applications. The main window will be seperated to three sub windows - each one display another one application.
I thought to use QX11EmbedWidget and QX11EmbedContainer widgets, but two problems with that:
The QX11Embed* is based on X11 protocol and I dont know if it's supported on non-x11 systems like Windows OS.
Since QT 5 these classes are not existing, and the QT documentation doesn't mention why.
So that I dont know whether to use it or not - I'll be happy to get an answers.
In addition, I see that the QT 5.1 contains QWidget::createWindowContainer(); function that in some posts it looks like this should be the replacement to the X11Embed. Can anyone please explian me more how can I use this function to create a QT widget that will run another application (a Calculator for example) inside its?
I have searched a lot in Google, and didn't find answers to my Qs.
Can anyone please help me? Am I on the right way?
Thanks!
If all three independent applications are written with Qt, and you have their source, you should be able to unify them just through the parenting of GUI objects in Qt.
http://qt-project.org/doc/qt-4.8/objecttrees.html
http://qt-project.org/doc/qt-4.8/widgets-and-layouts.html
http://qt-project.org/doc/qt-4.8/mainwindows-mdi.html
If you don't have access to them in that way, what you are talking about is like 3rd party window management. It is kind of like writing a shell, like Windows Explorer, that manipulates the state and the size of other window applications.
Use a program like Spy++ or AutoIt Spy for Windows and the similar ones for other OS's, and learn the identifying markings of your windows you want to control, like the class, the window title, etc. Or you can launch the exe yourself in a QProcess::startDetached() sort of thing.
http://qt-project.org/doc/qt-5.1/qtcore/qprocess.html#startDetached
Then using the OS dependent calls control the windows. The Qt library doesn't have this stuff built in for third party windows, only for ones under the QApplication that you launched. There are a lot of examples of doing things like this by AutoHotKey, or AHK. It is a scripting language that is made for automating a lot of things in the windows environment, and there is port for Mac as well (though I haven't tried the mac port myself).
So in the end you are looking at finding your window probably with a call like this:
#include <windows.h>
HWND hwnd_1 = ::FindWindow("Window_Class", "Window Name");
LONG retVal = GetWindowLongA(hwnd_1, GWL_STYLE); // to query the state of the window
Then manipulate the position and state of the window like so:
::MoveWindow(hwnd_1, x, y, width, height, TRUE);
::ShowWindow(hwnd_1, SW_SHOWMAXIMIZED);
You can even draw widgets on top of the windows you are controlling if you set your window flags correctly for the windows you are manipulating.
transparent QLabel with a pixmap
Cannot get QSystemTrayIcon to work correctly with activation reason
Some gotchas that come up in Windows when doing all of this, is finding out the quirks of the Windows UI when they set the Display scaling different from what you expect, and if you want to play nice with the Task bar, and handling all the modal windows of your programs you are manipulating.
So overall, it is do-able. Qt will make a nice interface for performing these commands, but in the end you are looking at a lot of work and debugging to get it in a beautiful, reliable, window manager.
Hope that helps.
I never tried it myself, but from the docs in Qt 5.1 I would try QWindow::fromId(WId id), which gives you a QWindow, which should be embeddable with createWindowContainer:
QWindow * QWindow::fromWinId(WId id) [static] Creates a local
representation of a window created by another process or by using
native libraries below Qt.
Given the handle id to a native window, this method creates a QWindow
object which can be used to represent the window when invoking methods
like setParent() and setTransientParent(). This can be used, on
platforms which support it, to embed a window inside a container or to
make a window stick on top of a window created by another process.
But no guarantee. :-)
I've been working on a project that will need a notifier in the system tray (sorry, "System Notification Area"). It will be a simple app that just generates popup notifications when it receives a message via a Zeromq socket.
I am not having any luck finding anything other than .NET resources and examples. Does anyone have a sample in C/C++?
I would start with this section of MSDN: Notifications and the Notification Area.
Then I'd check the NotificationIcon Sample in the Windows SDK.
What framework are you using? There should probably be several implementations for MFC, but there might different implementation for WTL and other frameworks. If you want to use the Windows API with no object orientation - well, you won't need any wrapper library then, but you can look at these libraries for example.
Here's one that has MFC and non-MFC version from CodeProject:
http://www.codeproject.com/KB/shell/systemtray.aspx
What you want here is probably ShowBalloon() function, which shows a balloon notification, but I'm pretty sure you must create a tray icon for that (can't have a notification balloon without having a tray icon).