In Windows how to get highlighted text in a window that belongs to another process using C++ or C#?

Question

It's in a C++ translation program. When user selects some text in some other program without pressing CTRL-C, I want to get the highlighted text so that I could translate it. C# solutions are welcome because this(text acquisition) is a relatively standalone component.

One possible solution is to add hook to mouse event. I detect the following messages: mouse drag with left button hold, then release left button. Then I send CTRL-C to the program and get the text from clipboard.

I save and restore clipboard so most programs would work well with the method. But I have observed some programs would process events like WM_KEYUP in their message loops. For these programs I send fake messages! Is there another safer way to get the highlighted text?

I was trying to find some API call to get text between two mouse cursor positions, but I cannot find one.

Answer 1

The right way to write a Windows program that interacts with another programs GUI interface is to use UI Automation . Specifically, you'll write a UI Automation Client .

It requires a bit of work, but a UI Automation solution will work with almost every other application. A hacky solution built on hooks and messages will also be a lot of work, but it will be very fragile. It will only work with certain kinds of applications in certain contexts. Lots of things can go wrong.