list-panel Class

Summary

A pane that displays a group of items and provides support for selecting items and performing actions on them. Each item may optionally have an image.

Package

capi

Superclasses

choice
simple-pane
sorted-object
titled-object

Subclasses

list-view
multi-column-list-panel

Initargs

Accessors

list-panel-right-click-selection-behavior
list-panel-keyboard-search-callback
list-panel-image-function
list-panel-state-image-function

Description

The class list-panel gains much of its behavior from choice, which is an abstract class that handles items and their selection. By default, a list panel has both horizontal and vertical scrollbars.

list-panel does not support the :no-selection interaction style. For a non-interactive list use a display-pane.

To scroll a list-panel, call scroll with scroll-operation :move.

mnemonic-title is interpreted as for menu.

color-function allows you to control the text colors on Microsoft Windows, Cocoa and GTK+. If color-function is non-nil, then it is a function used to compute the text color of each item, with signature:

color-function list-panel item state => result

When alternating-background is true, the list panel is drawn with alternating background on Cocoa. On GTK+ it provides a hint, which the theme can override. Experience suggests that theme may draw with alternating background even when alternating-background is false, but when it is true they tend to draw it always. The default value of alternating-background is nil.

state is a keyword representing the state of the item. It can be one of :normal, :selected or :disabled. The value result should be a value suitable for the function convert-color. The pane uses the converted color as the foreground color for the item item. color-function is called while list-panel is being drawn, so it should not do heavyweight computations.

Description: Filter

If filter is non-nil, the system automatically adds a filtering-layout above the list. The items in the list-panel are filtered by the value in the filtering-layout. Filtering displays only those items whose print representation matches the filter. (The print representation is the result of print-collection-item, and is what the user sees.) Only the items that match, or those that do not match if Exclude is set, are displayed in the list-panel.

Here filtering means mapping over the unfiltered items, collecting each item that matches the current setting in the filter, and then setting the items of the list-panel to the collected items.

For a list-panel with a filter, collection-items returns only the filtered items, and the selection (that is, the result of choice-selection and the argument to (setf choice-selection)) index into the filtered items.

Calling (setf collection-items) on a filtered list-panel sets an internal unfiltered list, and then clears the filtering so that all items are visible.

To get and set the unfiltered items, use the accessor list-panel-unfiltered-items. To access the filter-state, use list-panel-filter-state. To access both the unfiltered items and the filter simultaneously, which is especially useful when setting both of them at the same time, use list-panel-items-and-filter.

filter-automatic-p controls whether the filter automatically does the filtering whenever the text in the filter changes, and filter-callback defines the callback of the filtering-layout.

If filter-automatic-p is t, whenever a change occurs in the filter the list is refreshed against the new value in the filter. The filter-callback (if non-nil) is called with two arguments, the filtering-layout and the list-panel itself, when the user "confirms" (that is, she presses Return or clicks the Confirm button). If filter-automatic-p is false and filter-callback is :default, then the filtering-layout is given a callback that does the filtering when the user "confirms". If filter-automatic-p is false and filter-callback is non-nil, then no filtering is done explicitly, and it is the responsibility of the callback to do any filtering that is required.

filter-matches-title (default t) and filter-help-string (default t) are passed down to the filtering layout using the filtering-layout initargs :matches-title and :help-string respectively. See filtering-layout for a description of these initargs.

If filter-short-menu-text is true, the filter menu has a short title. For example if the filter is set for case-sensitive plain inclusive matching the short label is PMC. If filter-short-menu-text were false then this label would be Filter:C.

When filter-added-filters is non-nil, it adds additional filters that apply to the items of the list-panel. Each element of filter-added-filters must be one of:

The check-button and option-pane panes are displayed in the same row as the filter.

Before checking if an item in the list-panel matches the filter's text, the filter passes the item to the associated function from each selected check-button and from the selected item of each option-pane (unless the associated function is nil). If any of these functions returns nil, then the item is excluded (so it is not displayed). Note that the Exclude setting of the filter does not apply to the added filters, and the functions are called with the item in the list-panel, rather than its printed representation.

Any change in the selection of any of the check-button and option-pane panes causes the filter to be applied, which recomputes the displayed items.

There is a simple example of using filter-added-filters in:

(example-edit-file "capi/choice/filter-added-filters")

Notes: Filter

If you use filter:

1. You should not rely on the element-parent of the list-panel, because it is implemented by wrapping some layouts around the list-panel.
2. The filter is actually a filtering layout, so it has the same interactive semantics as filtering-layout.

Description: Keyboard search

keyboard-search-callback should be a function with signature:

keyboard-search-callback pane string position => index, last-match, last-match-reset-time

pane is the list-panel, string is a string to match and position is the item index from which the system thinks that the search should start.

string contains the character that the user typed, appended to the "last match", if there is one. There is a "last match" if the previous call to keyboard-search-callback returned it (see below).

index is an index in the collection-items to move to. Apart from an integer inside the items range of the list-panel, this can be nil, which means do nothing, or :no-change, which selects the current item.

last-match is a string that should be recorded as the "last match" (if it is not a string, the "last match" is reset). This is prepended to the character in the next call, if the character is typed before the "last match" is reset.

last-match-reset-time is the time to wait before resetting the "last match", in seconds. Once this time passes, the last match is reset to nil. If last-match-reset-time is nil, the default value (which defaults to 1) is used. This default value can be changed by set-list-panel-keyboard-search-reset-time.

You can simplify the implementation of keyboard-search-callback by using list-panel-search-with-function.

As a special case, passing :keyboard-search-callback t tells CAPI to use its own internal search mechanism in preference to the native one. That can be useful on GTK+, where the default is to use the native search mechanism (for GTK+ versions after 2.4).

Notes: Keyboard search

keyboard-search-callback is intended for searching, but it is not limited to doing a search, and in fact can be used for implementing other functionality. However, since the system waits for the result, if the callback does something heavy or interacts with the user, it should schedule it in some way and return, for example:

(defun my-keyboard-search-callback (pane string pos)
  (declare (ignore pane pos))
  ;; cause a call to display-message in event loop
  (mp:current-process-send
   (list 'capi:display-message
         (format nil "You pressed  ~a" string)))
  nil ; return nil so do nothing
  )

Description: Images

The image-function is called on an item to return an image associated with the item. It can return one of the following:

The state-image-function is called on an item to determine the state image: an additional optional image used to indicate the state of an item. It can return one of the above, or nil to indicate that there is no state image.

If image-lists is specified, it should be a plist containing the following keywords as keys. The corresponding values should be image-list objects.

Description: Right-click selection behavior

right-click-selection-behavior can take the following values:

All non-nil values pass the clicked item as data to the pane-menu:

The default value of right-click-selection-behavior is :no-change.

separators controls whether there are separators. Horizontal separators means that each row is separated from the previous row by a horizontal line. Vertical separators are applicable only in multi-column-list-panel, and means that by default each column is separated by a vertical line from the previous column. This can be overridden by the :separator option in the column specification (see entry for multi-column-list-panel). If separators is nil (the default), there are no separators. :both and t are equivalent, and specify both horizontal and vertical separators. :horizontal and :vertical specify separators for one direction.

Examples

(setq list (capi:contain
            (make-instance 'capi:list-panel
                           :items '(:red :blue :green)
                           :selected-item :blue
                           :print-function
                           'string-capitalize)))
 
(capi:apply-in-pane-process 
 list #'(setf capi:choice-selected-item) :red list)
 
(capi:apply-in-pane-process 
 list #'(setf capi:choice-selected-item) :green list)

(capi:contain (make-instance
               'capi:list-panel
               :items '(:red :blue :green)
               :print-function 'string-capitalize
               :selection-callback
                 #'(lambda (data interface)
                           (capi:display-message
                            "~S" data))))

This example illustrates the use of :right-click-selection-behavior:

(capi:define-interface click ()
  ((keyword :initarg :right-click-selection-behavior))
  (:panes
   (list-panel
    capi:list-panel
    :items '("foo" "bar" "baz" "quux")
    :visible-min-height '(:character 4)
    :pane-menu 'my-menu
    :interaction :multiple-selection
    :right-click-selection-behavior keyword)))
 
(defun my-menu (pane data x y)
  (declare (ignore pane x y))
  (make-instance 'capi:menu
                 :items (list "Hi There"
                              ""
                              "Here's the data:"
                              data)))
 
(capi:display
   (make-instance 'click
                  :right-click-selection-behavior
                  :clicked/restore/restore))

See also this example:

(example-edit-file "capi/choice/list-panel-pane-menu")

There are further examples here:

(example-edit-file "capi/choice/")

This example illustrates the use of color-function:

(example-edit-file "capi/applications/simple-symbol-browser")

There are further examples in 20 Self-contained examples.

See also

button-panel
double-list-panel
1.2.1 CAPI elements
3.1.4.1 Controlling Mnemonics
19.3.2 Matching resources for GTK+
5 Choices - panes with items
7 Programming with CAPI Windows
10.2.3 Prompting for an item in a list
13.10 Working with images
17 Drag and Drop