| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: object buttons cursor-position
This generic function is called when the user presses the left mouse
button while the mouse cursor is in the interior (client) area of a
window, dialog-item
, or hotspot
. An application
may add methods to this generic function to respond to mouse events in
these objects.
object is the window, dialog-item, or hotspot in
which the event occurred. If the event occurred in a dialog-item, then
this function will be called on the dialog-item
and also on its associated widget-window
. An application
could specialize on whichever object is more convenient (this is
typically the dialog-item
).
In any case, the built-in methods on the widget-window
normally should not be overridden,
because they implement the widget's built-in click behavior.
buttons is an integer indicating which mouse buttons and shift keys were down when the event occurred. The value is the result of applying logior to the values of the following bit-flag variables:
left-mouse-button
middle-mouse-button
right-mouse-button
first-x-button
(see *ignore-mouse-x-buttons*
)
second-x-button
(see *ignore-mouse-x-buttons*
),
shift-key
control-key
alt-key
Other bits might be turned on as well, so functions such as logtest should be used to determine whether a particular mouse button or shift key was down; for example,
(logtest right-mouse-button buttons)
will return true if and only if the right mouse button was down. For "down" events, the value includes the button or key being pressed now; for "up" events, the value does not include the button or key being released.
cursor-position is a position object indicating
the location of the mouse cursor when the event occurred. It is in
"stream coordinates", which are relative to the origin of the possibly
scrolled page (canvas) of the window; pixels are the unit of distance
unless the window is a scaling-stream
. (The origin of a
stream is typcially left at 0,0, which indicates the top-left corner
of the scrollable page; see stream-origin.)
See cg-events.htm for information about event handling in Common Graphics.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |