c++ - Simulating mouse clicks on Mac OS X does not work for some applications

Question

I'm writing an application for Mac OS X 10.6 and later in C++. One part of the application needs to simulate mouse movement and mouse clicks. I do this currently by posting CGEvent objects using CGEventPost(kCGHIDEventTap, event);.

This works, for the most part - I can simulate mouse movement and clicks just fine, but it seems to fail in some areas. For example:

• In Mozilla Firefox and Safari, I can click on all the menus, but cannot click on a link within a website. When I try, the link is highlighted, but the browser never follows the link. However, I can right-click on a link, select "open link in new tab", and everything works as expected. Solved - creating the mouse event using CGEventCreateMouseEvent(...) makes the event work within web browser.
• I can click on the "Dashboard" icon to brink up the dashboard, but I cannot click on the "i" button on any of the dashboard widgets. Similarly, clicking on any of the search results from the spotlight search widget doesn't work either.

This inconsistency is along application boundaries. What might be the cause?

Answer 1

What you need to do to convince these applications that you have in fact generated a click is to explicitly set the value of the "click state" field on the mouse up event to 1 (it defaults to 0). The following code will do it:

CGEventSetIntegerValueField(event, kCGMouseEventClickState, 1);

It also has to be set to 1 for the mouse down, but by using CGEventCreateMouseEvent() rather than CGEventCreate() that gets done for you.

I have tested this and it works in the 'i' buttons in the dashboard and the Spotlight search results.

(As an aside, if you were simulating a double click you would need to set the click state to 2 for both the mouse down and mouse up events of the second click.)