NAME

Tickit::Widget::Scroller - a widget displaying a scrollable collection of items

SYNOPSIS

 use Tickit;
 use Tickit::Widget::Scroller;
 use Tickit::Widget::Scroller::Item::Text;
 
 my $tickit = Tickit->new;
 
 my $scroller = Tickit::Widget::Scroller->new;

 $scroller->push(
    Tickit::Widget::Scroller::Item::Text->new( "Hello world" ),
    Tickit::Widget::Scroller::Item::Text->new( "Here are some lines" ),
    map { Tickit::Widget::Scroller::Item::Text->new( "<Line $_>" ) } 1 .. 50,
 );
 
 $tickit->set_root_widget( $scroller );
 
 $tickit->run

DESCRIPTION

This class provides a widget which displays a scrollable list of items. The view of the items is scrollable, able to display only a part of the list.

A Scroller widget stores a list of instances implementing the Tickit::Widget::Scroller::Item interface.

KEYBINDINGS

The following keys are bound

• Down

  Scroll one line down

• Up

  Scroll one line up

• PageDown

  Scroll half a window down

• PageUp

  Scroll half a window up

• Ctrl-Home

  Scroll to the top

• Ctrl-End

  Scroll to the bottom

CONSTRUCTOR

$scroller = Tickit::Widget::Scroller->new( %args )

Constructs a new Tickit::Widget::Scroller object. The new object will start with an empty list of items.

Takes the following named arguments:

gravity => STRING

Optional. If given the value bottom, resize events will attempt to preserve the item at the bottom of the screen. Otherwise, will preserve the top.

METHODS

$scroller->push( @items )

Append the given items to the end of the list.

If the Scroller is already at the tail (that is, the last line of the last item is on display), the newly added items will be displayed, possibly by scrolling downward if required. While the scroller isn't adjusted, by using any of the scroll methods, it will remain following the tail of the items, scrolling itself upwards as more are added.

$scroller->shift( $count )

Remove the given number of items from the start of the list.

If any of the items are on display, the Scroller will be scrolled upwards an amount sufficient to close the gap, ensuring the first remaining item is now at the top of the display.

$scroller->scroll( $delta )

Move the display up or down by the given $delta amount; with positive moving down. This will be a physical count of displayed lines; if some items occupy multiple lines, then fewer items may be scrolled than lines.

$scroller->scroll_to( $line, $itemidx, $itemline )

Moves the display up or down so that display line $line contains line $itemline of item $itemidx. Any of these counts may be negative to count backwards from the display lines, items, or lines within the item.

$scroller->scroll_to_top( $itemidx, $itemline )

Shortcut for scroll_to to set the top line of display; where $line is 0. If $itemline is undefined, it will be passed as 0. If $itemidx is also undefined, it will be passed as 0. Calling this method with no arguments, therefore scrolls to the very top of the display.

$scroller->scroll_to_bottom( $itemidx, $itemline )

Shortcut for scroll_to to set the bottom line of display; where $line is -1. If $itemline is undefined, it will be passed as -1. If $itemidx is also undefined, it will be passed as -1. Calling this method with no arguments, therefore scrolls to the very bottom of the display.

$itemidx = $scroller->line2item( $line )

( $itemidx, $itemline ) = $scroller->line2item( $line )

Returns the item index currently on display at the given line of the window. In list context, also returns the line number within item. If no window has been set, or there is no item on display at that line, undef or an empty list are returned. $line may be negative to count backward from the last line on display; the last line taking -1.

$line = $scroller->item2line( $itemidx, $itemline )

( $line, $offscreen ) = $scroller->item2line( $itemidx, $itemline )

Returns the display line in the window of the given line of the item at the given index. $itemidx may be given negative, to count backwards from the last item. $itemline may be negative to count backward from the last line of the item.

In list context, also returns a value describing the offscreen nature of the item. For items fully on display, this value is undef. If the given line of the given item is not on display because it is scrolled off either the top or bottom of the window, this value will be either "above" or "below" respectively.

TODO

• Abstract away the "item storage model" out of the actual widget. Implement more storage models, such as database-driven ones.. more dynamic.

• Keybindings

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>

cpanm Tickit::Widget::Scroller

perl -MCPAN -e shell
install Tickit::Widget::Scroller