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Prima::Lists(3) User Contributed Perl Documentation Prima::Lists(3)

NAME

Prima::Lists - list widgets

DESCRIPTION

The module provides several listbox classes that differ in the way items in the list widget are associated with data. The hierarchy of classes is as follows:

        AbstractListViewer
                AbstractListBox
                ListViewer
                        ProtectedListBox
                        ListBox

The root class "Prima::AbstractListViewer" provides a common interface that is though not usable directly. The main differences between classes are centered around the way the items are stored. The simplest organization of a text-only item list, provided by "Prima::ListBox", stores an array of text scalars in a widget. More elaborated storage and representation types are not realized, and the programmer is urged to use the more abstract classes to derive their own mechanisms. For example, for a list of items that contain text strings and icons see "Prima::DirectoryListBox" in Prima::Dialog::FileDialog. To organize an item storage different from "Prima::ListBox" it is usually enough to overload either the "Stringify", "MeasureItem", and "DrawItem" events, or their method counterparts: "get_item_text", "get_item_width", and "draw_items".

Prima::AbstractListViewer

"Prima::AbstractListViewer" is a descendant of "Prima::Widget::GroupScroller", and some of its properties are not described here.

The class provides an interface to generic list browsing functionality, plus functionality for text-oriented lists. The class is not usable directly.

Properties

If 1, the item height is changed automatically when the widget font is changed; this is useful for text items. If 0, the item height is not changed; this is useful for non-text items.

Default value: 1

An integer property, used to access the number of items in the list. Since it is tied to the item storage organization, and hence the possibility of changing the number of items, this property is often declared as read-only in descendants of "Prima::AbstractListViewer".
If 1, allows the items to be dragged interactively by pressing the Control key together with the left mouse button. If 0, item dragging is disabled.

Default value: 0

If 1, vertical grid lines between columns are drawn with "gridColor". Actual only in multi-column mode.

Default value: 1

Manages the way the user selects multiple items that is only actual when "multiSelect" is 1. If 0, the user must click each item to mark it as selected. If 1, the user can drag the mouse or use the Shift key plus arrow keys to perform range selection; the Control key can be used to select individual items.

Default value: 0

Selects the focused item index. If -1, no item is focused. It is mostly a run-time property, however, it can be set during the widget creation stage given that the item list is accessible at this stage as well.

Default value: -1

Color used for drawing vertical divider lines for multi-column list widgets. The list classes support also the indirect way of setting the grid color, as well as the widget does, via the "colorIndex" property. To achieve this, the "ci::Grid" constant is declared ( for more detail see "colorIndex" in Prima::Widget ).

Default value: "cl::Black".

If 1, only the items that fit vertically in the widget interiors are drawn. If 0, the partially visible items are drawn also.

Default value: 0

If 1, only the items that fit horizontally in the widget interiors are drawn. If 0, the partially visible items are drawn also. Actual only in the multi-column mode.

Default value: 0

Selects the height of the items in pixels. Since the list classes do not support items with variable heights, changes to this property affect all items.

Default value: default font height

Selects the width of the items in pixels. Since the list classes do not support items with variable widths, changes to this property affect all items.

Default value: default widget width

If 0, the user can only select one item, and it is reported by the "focusedItem" property. If 1, the user can select more than one item. In this case, the "focusedItem"'th item is not necessarily selected. To access the selected item list use the "selectedItems" property.

Default value: 0

If 0, the items are arranged vertically in a single column and the main scroll bar is vertical. If 1, the items are arranged in several columns, each "itemWidth" pixels wide. In this case, the main scroll bar is horizontal.
Horizontal offset of an item list in pixels.
Selects the first item drawn.
A read-only property. Returns the number of selected items.
ARRAY is an array of integer indices of selected items.
Sets the general direction of items in multi-column mode. If 1, items increase down-to-right. Otherwise, right-to-down.

Doesn't have any effect in single-column mode. Default value: 1.

Methods

Sets item indices from ARRAY in selected or deselected state, depending on the FLAG value, correspondingly 1 or 0.

Only for the multi-select mode.

Clears the selection

Only for the multi-select mode.

Called from within the "Paint" notification to draw items. The default behavior is to call the "DrawItem" notification for every item in the ITEM_DRAW_DATA array. ITEM_DRAW_DATA is an array or arrays, where each array consists of parameters passed to the "DrawItem" notification.

This method is overridden in some descendant classes to increase the speed of drawing. For example, "std_draw_text_items" is the optimized routine for drawing text-based items. It is used in the "Prima::ListBox" class.

See DrawItem for the description of the parameters.

Called by "std_draw_text_items" to draw a sequence of text items with indices from FIRST to LAST, by STEP, on CANVAS, starting at point X, Y, and incrementing the vertical position with OFFSET. CLIP_RECT is a reference to an array of four integers given in the inclusive-inclusive coordinates that represent the active clipping rectangle.

Note that OFFSET must be an integer, otherwise bad effects will be observed when text is drawn below Y=0

Returns the text string assigned to the INDEXth item. Since the class does not assume the item storage organization, the text is queried via the "Stringify" notification.
Returns width in pixels of the INDEXth item. Since the class does not assume the item storage organization, the value is queried via the "MeasureItem" notification.
Returns 1 if the INDEXth item is selected, 0 otherwise.
Calculates and returns four integers with rectangle coordinates of the INDEXth item. WIDTH and HEIGHT are optional parameters with pre-fetched dimensions of the widget; if not set, the dimensions are queried by calling the "size" property. If set, however, the "size" property is not called, thus some speed-up can be achieved.
Returns the index of an item that contains the point at (X,Y). If the point belongs to the item outside the widget's interior, returns the index of the first item outside the widget's interior in the direction of the point.
Redraws all items in the INDICES array.
Selects all items.

Only for the multi-select mode.

Sets the selection flag on the INDEXth item. If FLAG is 1, the item is selected. If 0, it is deselected.

Only for the multi-select mode.

Selects the INDEXth item.

Only for the multi-select mode.

An optimized method, draws text-based items. It is fully compatible with the "draw_items" interface and is used in the "Prima::ListBox" class.

The optimization is derived from the assumption that items maintain common background and foreground colors, that only differ in the selected and non-selected states. The routine groups drawing requests for selected and non-selected items, and then draws items with a reduced number of calls to the "color" property. While the background is drawn by the routine itself, the foreground ( usually text ) is delegated to the "draw_text_items" method, so that the text positioning and eventual decorations would be easier to implement.

ITEM_DRAW_DATA is an array of arrays of scalars, where each array contains parameters of the "DrawItem" notification. See DrawItem for the description of the parameters.

Toggles selection of the INDEXth item.

Only for the multi-select mode.

Deselects the INDEXth item.

Only for the multi-select mode.

Events

Called when the user presses the return key or double-clicks on an item. The index of the item is stored in "focusedItem".
Called when the user finishes the drag of an item from OLD_INDEX to NEW_INDEX position. The default action rearranges the item list according to the dragging action.
Called when the INDEXth item is to be drawn on CANVAS. X1, Y1, X2, Y2 define the item rectangle in widget coordinates where the item is to be drawn. SELECTED, FOCUSED, and PRELIGHT are boolean flags, if the item must be drawn correspondingly in selected and focused states, with or without the prelight effect.
Stores width in pixels of the INDEXth item into the REF scalar reference. This notification must be called from within the "begin_paint_info/end_paint_info" block.
Called when an item changes its selection state. INDEX is the index of the item, FLAG is its new selection state: 1 if it is selected, 0 if it is not.
Stores the text string associated with the INDEXth item into TEXT_REF scalar reference.

Prima::AbstractListBox

The same as its ascendant "Prima::AbstractListViewer" except that it does not the propagate "DrawItem" message, assuming that all items must be drawn as text strings.

Prima::ListViewer

The class implements an item storage mechanism but leaves the definition of the format of the item to the programmer. The items are accessible via the "items" property and several other helper routines.

The class also defines user navigation by accepting character keyboard input and jumping to the items that have text assigned with the first letter that matches the input.

"Prima::ListViewer" is derived from "Prima::AbstractListViewer".

Properties

Selects if the item width must be recalculated automatically when either the font or item list is changed.

Default value: 1

A read-only property; returns the number of items.
Accesses the storage array of the items. The format of items is not defined, it is merely treated as one scalar per index.

Methods

Appends an array of ITEMS to the end of the item list.
Recalculates all item widths. Adjusts "itemWidth" if "autoWidth" is set.
Deletes items from the list. INDICES can be either an array or a reference to an array of item indices.
Returns the width in pixels of the INDEXth item from the internal cache.
Returns an array of items. INDICES can be either an array or a reference to an array of item indices. Depending on the caller context, the results are different: in the array context the item list is returned; in scalar - only the first item from the list.
Inserts an array of items at the OFFSET index in the list. Offset must be a valid index; to insert items at the end of the list use the "add_items" method.

ITEMS can be either an array or a reference to an array of items.

Replaces existing items at the OFFSET index in the list. The offset must be a valid index.

ITEMS can be either an array or a reference to an array of items.

Prima::ProtectedListBox

A semi-demonstrational class derived from "Prima::ListViewer", implements certain protections for every item during drawing. Assuming that several item drawing algorithms can be used in the same widget, "Prima::ProtectedListBox" provides a safety layer between these. If an algorithm selects a font or a color and does not restore the old value, this does not affect the outlook of other items.

This functionality is implemented by overloading the "draw_items" method and also all graphic properties.

Prima::ListBox

Descendant of "Prima::ListViewer", declares that an item must be a single text string. Incorporating all the functionality of its predecessors, provides the standard workhorse listbox widget.

Synopsis

        my $lb = Prima::ListBox-> create(
                items       => [qw(First Second Third)],
                focusedItem => 2,
                onClick     => sub {
                        print $_[0]-> get_items( $_[0]-> focusedItem), " is selected\n";
                }
        );

Methods

Returns the text string associated with the INDEXth item. Since the item storage organization is implemented, does so without calling the "Stringify" notification.

AUTHOR

Dmitry Karasik, <dmitry@karasik.eu.org>.

SEE ALSO

Prima, Prima::Widget, Prima::ComboBox, Prima::Dialog::FileDialog, examples/editor.pl

2024-08-20 perl v5.40.0