Get text drawn by ExtTextOut

Question

I'am trying to get the text outputing by ExtTextOutW function, and the first thing that i came up with is, that go and hook this function, for example by injecting dll in the target process. So from there i can get the hdc, text and flags. However, i have the application that calls this function many many times, so i don't want to hook and make checks for all the calls. Is there a way, i can get the text printed on form by ExtTextOutW without hooking it, maybe using the hdc where it outputs the data?

Answer 1

Hooking is the only way you can get the parameter data that is being passed to ExtTextOutW(). If you are only interested in data for a specific HDC, you will have to filter accordingly. However, HDCs tend to be created dynamically when needed, so you likely cannot filter on the actual HDC value itself, as it will be different each time. Fortunately, if the HDC belongs to a window (and it sounds like you want to intercept calls for a specific window), you can use WindowFromDC() to get the HWND of the HDC that is being drawn on, and then filter on that as needed.