Programmatically open Mac Help menu

问题:

I'm integrating a GTK# application into Mac OS X. GTK on Mac OS X is a wrapper over some Cocoa and Carbon fundamentals. We have some platform-specific stuff directly using Carbon global menu APIs (it's more low-level and flexible than Cocoa, and we don't need to be 64-bit).

It seems that GTK swallows up all the keyboard events before Carbon dispatches them as commands. This makes sense, because there is no mapping of Carbon commands into the GTK world. In general, this isn't a problem, because we have a global key event handler and dispatch everything via our own command system. However, this seems to be preventing Cmd-? from opening the Help search menu, and I cannot find a way to do this programmatically.

Menu Manager's MenuSelect function is promising, but I haven't figured out a way to determine the coordinate automatically, and for some reason it only works when I hit the combination twice...

Alternatively, a way to dispatch the Cmd-? keystroke to Carbon's command handling or synthesize the command event directly would be good, but I haven't had any luck in that area.

Carbon's ProcessHICommand isn't any use without a command ID and I can't figure out what it is (if there is one)

Regarding Cocoa, I can get hold of the NSWindow and call InterpretKeyEvents, but I haven't had any luck success synthesizing the NSEvent - it just beeps. The event I'm using is

var evt = NSEvent.KeyEvent (NSEventType.KeyDown, System.Drawing.PointF.Empty,
    NSEventModifierMask.CommandKeyMask | NSEventModifierMask.ShiftKeyMask,
    0, win.WindowNumber, NSGraphicsContext.CurrentContext, "?", "?",
    false, (ushort) keycode);

Keycode is determined from a GTK keymap to be 44. I confirmed that the keycode was correct using a plain MonoMac (Cocoa) app but InterpretKeyEvents did not work with the event in that app either. And I can't find any selector associated with the command.

回答1:

You can use accessibility APIs to fake a press on the menu item.

NSString *helpMenuTitle = [[[[NSApplication sharedApplication] mainMenu] itemWithTag:HELP_MENU_TAG] title];
AXUIElementRef appElement = AXUIElementCreateApplication(getpid());
AXUIElementRef menuBar;
AXError error = AXUIElementCopyAttributeValue(appElement,
                                              kAXMenuBarAttribute,
                                              (CFTypeRef *)&menuBar);
if (error) {
    return;
}

CFIndex count = -1;
error = AXUIElementGetAttributeValueCount(menuBar, kAXChildrenAttribute, &count);
if (error) {
    CFRelease(menuBar);
    return;
}

NSArray *children = nil;
error = AXUIElementCopyAttributeValues(menuBar, kAXChildrenAttribute, 0, count, (CFArrayRef *)&children);
if (error) {
    CFRelease(menuBar);
    return;
}

for (id child in children) {
    AXUIElementRef element = (AXUIElementRef)child;
    id title;
    AXError error = AXUIElementCopyAttributeValue(element,
                                                  kAXTitleAttribute,
                                                  (CFTypeRef *)&title);
    if ([title isEqualToString:helpMenuTitle]) {
        AXUIElementPerformAction(element, kAXPressAction);
        CFRelease(title);
        break;
    }
    CFRelease(title);
}
CFRelease(menuBar);
[children release];

回答2:

You could do this via calling from C / Objective-C a AppleScript (GUI) script , that would essentially do the pointing and clicking of a user just as a user would do, to open the help menu program-matically.