/**
* menu-aim is a jQuery plugin for dropdown menus that can differentiate
* between a user trying hover over a dropdown item vs trying to navigate into
* a submenu's contents.
*
* menu-aim assumes that you have are using a menu with submenus that expand
* to the menu's right. It will fire events when the user's mouse enters a new
* dropdown item *and* when that item is being intentionally hovered over.
*
* __________________________
* | Monkeys >| Gorilla |
* | Gorillas >| Content |
* | Chimps >| Here |
* |___________|____________|
*
* being shown on the right. Imagine that the user's cursor is hovering over
* area.
*
* This problem is normally solved using timeouts and delays. menu-aim tries to
* solve this by detecting the direction of the user's mouse movement. This can
* make for quicker transitions when navigating up and down the menu. The
* dropdown.
*
* Use like so:
*
* activate: $.noop, // fired on row activation
* deactivate: $.noop, // fired on row deactivation
* });
*
* ...to receive events when a menu's row has been purposefully (de)activated.
*
* The following options can be passed to menuAim. All functions execute with
* the relevant row's HTML element as the execution context ('this'):
*
* .menuAim({
* // Function to call when a row is purposefully activated. Use this
* // to show a submenu's content for the activated row.
* activate: function() {},
*
* // Function to call when a row is deactivated.
* deactivate: function() {},
*
* // Function to call when mouse enters a menu row. Entering a row
* // does not mean the row has been activated, as the user may be
* // mousing over to a submenu.
* enter: function() {},
*
* // Function to call when mouse exits a menu row.
* exit: function() {},
*
* // Selector for identifying which elements in the menu are rows
*
* // You may have some menu rows that aren't submenus and therefore
* });
*
* https://github.com/kamens/jQuery-menu-aim
*/
(function($) {
{
),
,
[],
,
,
({
,
,
// bigger = more forgivey when entering submenu
,
,
,
noop
);
// number of past mouse locations to track
// ms delay when user appears to be entering submenu
/**
* Keep track of the last few locations of the mouse.
*/
{
});
{
();
}
};
/**
* Cancel possible row activations when leaving the menu entirely
*/
{
{
);
}
};
/**
* Trigger a possible row activation whenever entering a new row.
*/
{
{
// Cancel any previous activation delays
);
}
);
);
},
{
);
};
/**
* Activate a menu row.
*/
{
{
;
}
{
);
}
);
;
};
/**
* Possibly activate a menu row. If mouse movement indicates that we
* shouldn't activate yet because user may be trying to enter
* a submenu's content, then delay and check again later.
*/
{
();
{
{
);
);
{
);
}
};
/**
* Return the amount of time that should be used as a delay before the
* currently hovered row is activated.
*
* Returns 0 if the activation should happen immediately. Otherwise,
* returns the number of milliseconds that should be delayed before
* checking again to see if the row should be activated.
*/
{
{
// If there is no other submenu row already active, then
// go ahead and activate immediately.
;
}
(),
{
(),
tolerance
},
{
(),
tolerance
},
],
];
{
;
}
{
;
}
||
{
// If the previous mouse location was outside of the entire
// menu's bounds, immediately activate.
;
}
&&
{
// If the mouse hasn't moved since the last time we checked
// for activation status, immediately activate.
;
}
// Detect if the user is moving towards the currently activated
// submenu.
//
// If the mouse is heading relatively clearly towards
// the submenu's content, we should wait and give the user more
// time before activating a new row. If the mouse is heading
// elsewhere, we can immediately activate a new row.
//
// We detect this by calculating the slope formed between the
// current mouse location and the upper/lower right points of
// the menu. We do the same for the previous mouse location.
// If the current mouse location's slopes are
// increasing/decreasing appropriately compared to the
// previous's, we know the user is moving toward the submenu.
//
// Note that since the y-axis increases as the cursor moves
// down the screen, we are looking for the slope between the
// cursor and the upper left corner to decrease over time, not
// increase (somewhat counterintuitively).
{
);
};
),
),
),
);
&&
{
// Mouse is moving from previous location towards the
// currently activated submenu. Delay before activating a
// new menu row, because user may be moving into submenu.
;
;
}
;
;
};
/**
* Hook up initial menu events
*/
{
$menu
)
)
)
);
);
};
();
;
};
})(jQuery);