An output pane is a pane whose display and input behavior can be controlled by the programmer.









A function that knows how to redisplay the pane.


A list of input specifications.


A function called when the pane is scrolled, or nil . The default is nil .


A boolean specifying whether the pane itself is responsible for drawing into the visible area.


A function called when the pane gets or loses the input focus, or nil . The default is nil .


A function called when the pane is resized, or nil . The default is nil .


A platform-specific plist of options controlling how graphics are drawn.






The class output-pane is a subclass of gp:graphics-port-mixin which means that it supports many of the graphics ports drawing operations. When the CAPI needs to redisplay a region of the output pane, the display-callback gets called with the output-pane and the x , y , width and height of the region that needs redrawing. The display-callback should then use graphics port operations to redisplay that area. To force an area to be re-displayed, use the function invalidate-rectangle.

The input-model provides a means to get callbacks on mouse and keyboard gestures. An input-model is a list of mappings from gesture to callback, where each mapping is a list

( gesture callback . extra-callback-args )

gesture specifies the type of gesture, which can be gesture spec, character, button, key, command or motion.

In a gesture spec mapping, gesture can be simply the keyword :gesture-spec , which matches any keyboard input. For specific mappings, gesture is a list

(:gesture-spec data [modifier]* )

in which data is a character object or an integer between 0 and char-code-limit (interpreted as the character object obtained by code-char ), or a keyword naming a function key, and each modifier is one of the keywords :shift , :control and :meta . Note that the :meta modifier is received only when the keys style is :emacs (see interface-keys-style). On Cocoa, the modifer value :hyper is interpreted as the Command key for mouse input in dialogs (though note that Command is reserved for menu accelerators in interfaces).

Also data can be a string which is interpreted as a gesture spec as if by sys:coerce-to-gesture-spec . See the LispWorks Reference Manual for a description of this and other functions for manipulating gesture spec objects.

In a character mapping, gesture can be simply the keyword :character , which matches any character input. For specific mappings, gesture can be a list containing a single character object char , or a list

( char )

Note: where input would match both a gesture spec mapping and a character mapping, the gesture spec mapping takes precedence.

In a button mapping, gesture should be list

( button action [modifiers]* )

where button is one of :button-1 , :button-2 or :button-3 denoting the mouse buttons. action is one of :press , :release , :second-press and :motion , and each modifier is one of the keywords :shift , :control and :meta .

In a key mapping, gesture should contain the key in question (or the keyword :key meaning any key) along with an optional action (one of :press or :release ) and zero or more keyboard modifiers.

In a motion mapping, gesture can either be defined in terms of dragging a button (in which case it is defined as a button gesture with action :motion ), or it can be defined for motions whilst no button is down by just specifying the keyword :motion with no additional arguments.

In a command mapping, gesture should be a command which is defined using define-command, and provides an alias for a gesture. The following commands are predefined:


(:button-3 :release) on Windows.

(:button-3 :press) on Motif.

(:button-1 :press :control) on Mac OS X.


(:button-3 :press :control) on Windows, Motif and Mac OS X.


(:gesture-spec :f10 :shift) on Windows, Motif and Mac OS X.

Note that it is recommended you follow the style guidelines and conventions of the platform you are developing for when mapping gestures to results.

When user input matches gesture , callback is called with standard arguments and any extra-callback-args as extra arguments. The standard arguments are the output-pane , the x cursor position, the y cursor position, and in the case of gesture spec, character or key mappings, the input object that matched.

If pane-can-scroll is true then the pane is responsible for handling scrolling, by redrawing. It should draw into the visible area according to the scroll parameters. An example of this is editor-pane. If pane-can-scroll is nil , then the CAPI is responsible for scrolling over the data range. The default value is nil . See the example in output-panes/scroll-test.lisp .

When the output pane is scrolled, the CAPI calls the scroll-callback if this is non- nil . The arguments of the scroll callback are the output-pane, the direction ( :vertical , :horizontal or :pan ), the scroll operation ( :move , :drag , :step or :page ), the amount of scrolling (an integer), and a keyword argument :interactive . This has value t if the scroll was invoked interactively, and value nil if the scroll was programmatic, such as via the function scroll. In the Mac OS X Cocoa implementation the direction is always :pan . See the following CAPI example files:


focus-callback , if non- nil , is a function of two arguments. The first argument is the output-pane itself, and the second is a boolean. When the output-pane gets the focus, focus-callback is called with second argument t , and when the output-pane loses the focus, focus-callback is called with second argument nil .

resize-callback , if non- nil , is a function of five arguments called when the output-pane is resized. The first argument is the output-pane itself, and the rest are its new geometry: x , y , width and height .

graphics-options is currently only used by the Mac OS X Cocoa implementation. The single option defined is :text-rendering , with allowed values:


Draw glyphs directly using Core Graphics. This only draws characters with glyphs in the chosen font.


Draw using ATSUI APIs where possible.This is slower but can handle more characters.


Firstly, here is an example that draws a circle in an output pane.

(defun display-circle (self x y width height)
  (declare (ignore x y width height))
  (gp:draw-circle self 200 200 200 :filled t))
(capi:contain (make-instance
               :display-callback 'display-circle)
              :best-width 200 :best-height 200)

Here is an example that shows how to use a button gesture.

(defun test-callback (self x y)
   "Pressed button 1 at (~S,~S) in ~S" x y self))
  :title "Press button 1:"
  :input-model `(((:button-1 :press)
 :best-width 200 :best-height 200)

This example illustrates gesture spec mappings.

(defun draw-input (self x y gspec)
  (let ((data (sys:gesture-spec-data gspec))
        (mods (sys:gesture-spec-modifiers gspec)))
     (with-output-to-string (ss) 
        gspec ss :force-shift-for-upcase nil))
     x y)))
  :title "Press keys in the pane..."
  :input-model '((:gesture-spec
 :best-width 200 :best-height 200)
  :title "Press Control-a in the pane..."
  :input-model '(((:gesture-spec "Control-a")
 :best-width 200 :best-height 200)

Here is a simple example that draws the character typed at the cursor point.

(defun draw-character (self x y character)
  (gp:draw-character self character x y))
  :title "Press keys in the pane..."
  :input-model '((:character draw-character)))
 :best-width 200 :best-height 200)

This example shows how to use the motion gesture.

(defun draw-red-blob (self x y)
  (gp:draw-circle self x y 3 
                  :filled t 
                  :foreground :red))
  :title "Drag button-1 across this pane."
  :input-model '(((:button-1 :motion)
                 ((:button-1 :motion :control)
 :best-width 200 :best-height 200)

This example illustrates the use of focus-callback :

  #'(lambda (x y)
      (format t 
              "Pane ~a ~:[lost~;got~] the focus~%" 
              x y))))

This example illustrates the use of graphics-options to specify ATSUI drawing on Cocoa:

(defvar *string* 
  (coerce (loop for i from 0 below 60
                collect (code-char (* 5 i))) 
 (make-instance 'capi:output-pane 
                :visible-min-width 400 
                :visible-max-height 50
                #'(lambda (pane x y w h)  
                    (gp:draw-string pane 
                                    10 10)) 
                '(:text-rendering :atsui)))

There are further examples in the directory examples/capi/output-panes/ .

See also


LispWorks CAPI Reference Manual - 11 Apr 2005