/ 
TUI-Vision-2.000_002
/ TScroller

NAME

TScroller - base class for scrollable views in Turbo Vision

HIERARCHY

TObject
  TView
    TScroller
      TTextDevice
        TTerminal

SYNOPSIS

use TUI::Views;

my $scroller = TScroller->new(
  bounds      => $bounds,
  aHScrollBar => $hBar,
  aVScrollBar => $vBar
);

$scroller->setLimit(100, 50);
$scroller->scrollTo(10, 5);

DESCRIPTION

TScroller provides the core infrastructure for scrollable views in Turbo Vision. It maintains a two-dimensional scroll offset and coordinates scrolling behavior between the view and optional horizontal and vertical scroll bars.

The class itself does not render content. Instead, it serves as a base class for views that display scrollable data, such as text devices and terminal-like output views. Descendants are responsible for drawing their content relative to the current scroll position.

TScroller keeps its internal scroll offset synchronized with attached scroll bars. When the scroll bars change, the scroller updates its offset and redraws the view. Conversely, programmatic changes to the scroll position are reflected in the scroll bars.

ATTRIBUTES

The following attributes describe the scrolling state of the view. Attributes marked as read-only are managed internally.

delta

Current scroll offset as a point (TPoint). Represents the horizontal and vertical scroll position.

limit

Maximum allowed scroll offset (TPoint). Defines the bounds of the scrollable area.

aHScrollBar

Reference to the horizontal scroll bar (TScrollBar), if present.

aVScrollBar

Reference to the vertical scroll bar (TScrollBar), if present.

drawLock

Internal counter used to suppress redraw operations during batch updates.

drawFlag

Indicates whether a redraw is pending once drawing is re-enabled.

CONSTRUCTOR

new

my $scroller = TScroller->new(
  bounds      => $bounds,
  aHScrollBar => $hBar,
  aVScrollBar => $vBar
);

Creates a new scroller with the specified bounds and optional scroll bars.

bounds

Bounding rectangle of the scroller (TRect).

aHScrollBar

Horizontal scroll bar associated with the scroller (TScrollBar or undef).

aVScrollBar

Vertical scroll bar associated with the scroller (TScrollBar or undef).

new_TScroller

my $scroller = new_TScroller($bounds, $hBar | undef, $vBar | undef);

Factory-style constructor using positional arguments.

This constructor is equivalent to calling new with named parameters and is provided for compatibility with traditional Turbo Vision construction patterns.

DESTRUCTOR

DEMOLISH

$self->DEMOLISH($in_global_destruction);

Destroys the scroller and releases references to associated scroll bars. This method corresponds to the Turbo Vision destructor and is normally invoked automatically.

METHODS

changeBounds

$scroller->changeBounds($bounds);

Updates the bounds of the scroller and recalculates internal geometry.

checkDraw

$scroller->checkDraw();

Performs a deferred redraw if drawing was previously suppressed.

getPalette

my $palette = $scroller->getPalette();

Returns the color palette used by the scroller.

handleEvent

$scroller->handleEvent($event);

Processes events relevant to scrolling, including notifications from attached scroll bars.

scrollDraw

$scroller->scrollDraw();

Synchronizes the internal scroll offset with the scroll bar values and redraws the view if necessary.

scrollTo

$scroller->scrollTo($x, $y);

Sets the scroll position to the specified coordinates.

setLimit

$scroller->setLimit($x, $y);

Defines the maximum scrollable range and updates the scroll bars accordingly.

setState

$scroller->setState($state, $enable);

Updates the state flags of the scroller and redraws if required.

shutDown

$scroller->shutDown();

Shuts down the scroller and clears associated resources.

AUTHORS

Borland International (original Turbo Vision design)
J. Schneider <brickpool@cpan.org> (Perl implementation and maintenance)

COPYRIGHT AND LICENSE

Copyright (c) 1990-1994, 1997 by Borland International

Copyright (c) 2025-2026 the "AUTHORS" as listed above.

This software is licensed under the MIT license (see the LICENSE file, which is part of the distribution).