Get the word under the mouse cursor in Windows

Question

Greetings everyone,

A friend and I are discussing the possibility of a new project: A translation program that will pop up a translation whenever you hover over any word in any control, even static, non-editable ones. I know there are many browser plugins to do this sort of thing on webpages; we're thinking about how we would do it system-wide (on Windows).

Of course, the key difficulty is figuring out the word the user is hovering over. I'm aware of MSAA and Automation, but as far as I can tell, those things only allow you to get the entire contents of a control, not the specific word the mouse is over.

I stumbled upon this (proprietary) application that does pretty much exactly what we want to do: http://www.gettranslateit.com/

Somehow they are able to get the exact word the user is hovering over in almost any application (It seems to have trouble in a few apps, notably Windows Explorer). It even grabs text out of obviously custom-drawn controls, somehow. At first I thought it must be using OCR. But even when I shrink the font so far down that the text becomes a completely unreadable blob, it can still recognize words perfectly. (And yet, it doesn't recognize anything if I change the font to Wingdings. But maybe that's by design?)

Any ideas as to how it's achieving this seemingly impossible task?

EDIT: It doesn't work with Wingdings, but it does work with some other nonsense fonts, so I've confirmed it can't be OCR.

Answer 1

您可以捕获将文本输出到显示器的GDI调用，然后找出光标所在的单词边界框。

Answer 2

Well, for GDI controls you can get the position and size of the control, and you can usually get the font info. For example, with static text controls you'd use WM_GETFONT . Then once you have that you can get the position of the mouse relative to the position of the control and use one of the font functions , perhaps something like GetTextExtentPoint32 to figure out what is under the cursor. I'm pretty sure the answer lies in that direction...

You can run dumpbin /imports on the other application and see what APIs they are calling.