Win32 call order

Question

Hi all,

I have two windows that I send scripted input to. The procedure goes as this

BringWindowToTop( window1 );
i = Build input structures( window1 );
SendInput(i);

BringWindowToTop( window2 );
i = Build input structures( window2 );
SendInput(i);

I was having trouble with inputs not being sent and the correct time. I put delays after each call and saw that input from the first SendInput() was processed after window2 is brought to top. Same thing at the end of the loop as well.

Are SendInput calls buffered? If so, how can I make sure of a serial execution of this code?

Thanks

Answer 1

From the MSDN page:

The SendInput function inserts the events in the INPUT structures serially into the keyboard or mouse input stream. These events are not interspersed with other keyboard or mouse input events inserted either by the user (with the keyboard or mouse) or by calls to keybd_event, mouse_event, or other calls to SendInput.

So SendInput is inserting into the input stream where, presumably, BringWindowToTop is executing serially, or inserting into an events queue that is processed first. Perhaps you could find an event to call the second SendInput from, which will be executed after the first window is brought to the front.

Answer 2

Input, like most messages in Win32, goes through two phases. First it is posted into a queue. At this point the destination window is already determined. Then when the receiving program is idle it is processed. Even though the input might not be processed until after the second window is brought forward in the Z-order, the input messages should have been queued to the first window.

Does the behavior rely only on which window the input goes to, or does the program also have to be frontmost when the message is fully processed?

Anyway, since you are trying to send input to specific windows and not whatever the user made active, why not PostMessage the events such as WM_BUTTONDOWN and WM_KEYPRESS directly to their destinations?