Info Catalog elisp: Click Events elisp: Input Events elisp: Button-Down Events

elisp: Drag Events

 
 20.7.5 Drag Events
 ------------------
 
 With Emacs, you can have a drag event without even changing your
 clothes.  A “drag event” happens every time the user presses a mouse
 button and then moves the mouse to a different character position before
 releasing the button.  Like all mouse events, drag events are
 represented in Lisp as lists.  The lists record both the starting mouse
 position and the final position, like this:
 
      (EVENT-TYPE
       (WINDOW1 START-POSITION)
       (WINDOW2 END-POSITION))
 
    For a drag event, the name of the symbol EVENT-TYPE contains the
 prefix ‘drag-’.  For example, dragging the mouse with button 2 held down
 generates a ‘drag-mouse-2’ event.  The second and third elements of the
 event give the starting and ending position of the drag, as mouse
 position lists (Click Events).  You can access the second
 element of any mouse event in the same way.  However, the drag event may
 end outside the boundaries of the frame that was initially selected.  In
 that case, the third element’s position list contains that frame in
 place of a window.
 
    The ‘drag-’ prefix follows the modifier key prefixes such as ‘C-’ and
 ‘M-’.
 
    If ‘read-key-sequence’ receives a drag event that has no key binding,
 and the corresponding click event does have a binding, it changes the
 drag event into a click event at the drag’s starting position.  This
 means that you don’t have to distinguish between click and drag events
 unless you want to.
 

Info Catalog elisp: Click Events elisp: Input Events elisp: Button-Down Events