It mentions that window names are stored in quote "a special place", but does not explain how this "special place" can be accessed from a different process without a syscall/context switching. and that can't be right because there's no way Windows keeps a copy of the text for every single window/control on the system, on every single process. Which seems to imply that the text for every window that exists is accessible without a context switch. This means that GetWindowText got the window name without performing a context switch. I used a usermode debugger so I certainly didn't end up in kernelmode while stepping without realizing it. None of these API calls seem to be able to read a string in memory not owned by the calling process. WCSToMBEx (which is basically WideCharToMultiByte).GetWindowThreadProcessId (in GetWindowLong).I attached a debugger and stepped through the GetWindowTextA call, manually stepping through everything except these API calls (in order):
HWND winmine = FindWindow(NULL,"Minesweeper") MessageBox(0,"Attach debugger and set bp","on GetWindowTextA",0) int CALLBACK WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) I wrote a simple program to call GetWindowText with a handle to a window in a different process. Oops, that came out even funkier! (the old bug in the Quote Original that does strange stuff on line wraps).I wanted to figure out what the syscalls behind GetWindowText are. LRESULT got = SendMessage( wnd, WM_GETTEXT, WPARAM length = SendMessage( wnd, WM_GETTEXTLENGTH, 0, (sorry about the lack of formatting it looks like the tags support in the forum is temporarily not working) LRESULT got = SendMessage( wnd, WM_GETTEXT, length+1, (LPARAM)buffy ) WPARAM length = SendMessage( wnd, WM_GETTEXTLENGTH, 0, 0 )
In any event, here is a homemade GetWindowText(), which uses SendMessage() and WM_GETTEXT, as you requested (it is also using the string object from STL: I'll be happy if someone would show a code example with his reply.ĭo you know there is a GetWindowText() API call? So I'm trying to use a SendMessage API function with the parameter of WM_GETTEXT, but i don't know how to assign the char buffer to the last parameter of the function.Īnd what sort of SendMessage declaration i should use ? I want to recieve text from a combo on a different process. Threaded View: This topic has 3 replies on 1 page
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