Class ScrollBar

java.lang.Object

com.googlecode.lanterna.gui2.AbstractComponent<ScrollBar>

com.googlecode.lanterna.gui2.ScrollBar

All Implemented Interfaces:

Component, TextGUIElement

public class ScrollBar
extends AbstractComponent<ScrollBar>

Classic scrollbar that can be used to display where inside a larger component a view is showing. This implementation is not interactable and needs to be driven externally, meaning you can't focus on the scrollbar itself, you have to update its state as part of another component being modified. ScrollBars are either horizontal or vertical, which affects the way they appear and how they are drawn.

This class works on two concepts, the min-position-max values and the view size. The minimum value is always 0 and cannot be changed. The maximum value is 100 and can be adjusted programmatically. Position value is whever along the axis of 0 to max the scrollbar's tracker currently is placed. The view size is an important concept, it determines how big the tracker should be and limits the position so that it can only reach maximum value - view size.

The regular way to use the ScrollBar class is to tie it to the model-view of another component and set the scrollbar's maximum to the total height (or width, if the scrollbar is horizontal) of the model-view. View size should then be assigned based on the current size of the view, meaning as the terminal and/or the GUI changes and the components visible space changes, the scrollbar's view size is updated along with it. Finally the position of the scrollbar should be equal to the scroll offset in the component.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ScrollBar.DefaultScrollBarRenderer	Default renderer for ScrollBar which will be used unless overridden.
static class	ScrollBar.ScrollBarRenderer	Helper class for making new ScrollBar renderers a little bit cleaner

Field Summary

Fields

Modifier and Type	Field	Description
private final Direction	direction
private int	maximum
private int	position
private int	viewSize

Constructor Summary

Constructors

Constructor	Description
ScrollBar(Direction direction)	Creates a new ScrollBar with a specified direction

Method Summary

Modifier and Type	Method	Description
protected ComponentRenderer<ScrollBar>	createDefaultRenderer()	When you create a custom component, you need to implement this method and return a Renderer which is responsible for taking care of sizing the component, rendering it and choosing where to place the cursor (if Interactable).
Direction	getDirection()	Returns the direction of this ScrollBar
int	getScrollMaximum()	Returns the maximum scroll value
int	getScrollPosition()	Returns the position of the ScrollBar's tracker
int	getViewSize()	Returns the view size of the scrollbar
ScrollBar	setScrollMaximum(int maximum)	Sets the maximum value the scrollbar's position (minus the view size) can have
ScrollBar	setScrollPosition(int position)	Sets the scrollbar's position, should be a value between 0 and maximum - view size
ScrollBar	setViewSize(int viewSize)	Sets the view size of the scrollbar, determining how big the scrollbar's tracker should be and also affecting the maximum value of tracker's position

Methods inherited from class AbstractComponent

addTo, calculatePreferredSize, draw, getBasePane, getGlobalPosition, getLayoutData, getParent, getPosition, getPreferredSize, getRenderer, getSize, getTextGUI, getTheme, getThemeDefinition, hasParent, invalidate, isInside, isInvalid, isVisible, onAdded, onAfterDrawing, onBeforeDrawing, onRemoved, runOnGUIThreadIfExistsOtherwiseRunDirect, self, setLayoutData, setPosition, setPreferredSize, setRenderer, setSize, setTheme, setVisible, toBasePane, toGlobal, withBorder

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

direction

private final Direction direction

maximum

private int maximum

position

private int position

viewSize

private int viewSize

Constructor Details

ScrollBar

public ScrollBar(Direction direction)

Creates a new ScrollBar with a specified direction

Parameters:

direction - Direction of the scrollbar

Method Details

getDirection

public Direction getDirection()

Returns the direction of this ScrollBar

Returns:

Direction of this ScrollBar

setScrollMaximum

public ScrollBar setScrollMaximum(int maximum)

Sets the maximum value the scrollbar's position (minus the view size) can have

Parameters:

maximum - Maximum value

Returns:

Itself

getScrollMaximum

public int getScrollMaximum()

Returns the maximum scroll value

Returns:

Maximum scroll value

setScrollPosition

public ScrollBar setScrollPosition(int position)

Sets the scrollbar's position, should be a value between 0 and maximum - view size

Parameters:

position - Scrollbar's tracker's position

Returns:

Itself

getScrollPosition

public int getScrollPosition()

Returns the position of the ScrollBar's tracker

Returns:

Position of the ScrollBar's tracker

setViewSize

public ScrollBar setViewSize(int viewSize)

Sets the view size of the scrollbar, determining how big the scrollbar's tracker should be and also affecting the maximum value of tracker's position

Parameters:

viewSize - View size of the scrollbar

Returns:

Itself

getViewSize

public int getViewSize()

Returns the view size of the scrollbar

Returns:

View size of the scrollbar

createDefaultRenderer

protected ComponentRenderer<ScrollBar> createDefaultRenderer()

Description copied from class: AbstractComponent

When you create a custom component, you need to implement this method and return a Renderer which is responsible for taking care of sizing the component, rendering it and choosing where to place the cursor (if Interactable). This value is intended to be overridden by custom themes.

Specified by:

createDefaultRenderer in class AbstractComponent<ScrollBar>

Returns:

Renderer to use when sizing and drawing this component