ScrollView

#include <ScrollView.hpp>

Inherits: Widget

A clipping container that lets a child widget be scrolled inside a fixed viewport.

ScrollView renders its child into an internal viewport and only copies the visible region back to the parent buffer. This makes it useful for long text blocks, logs, and any content that should be partially visible inside a smaller area.

Public Methods

Return	Name	Description
	`ScrollView`	Defaulted constructor.
	`ScrollView` `explicit`
`void`	`setContent`	Sets the widget to display inside the scroll view.
`std::shared_ptr< Widget >`	`getContent` `const` `inline`	Gets the current child widget.
`void`	`setContentSize`	Sets an explicit content size for the scrollable area.
`void`	`clearContentSize`	Clears any explicit content size and falls back to measure().
`int`	`scrollX` `const` `inline`	Gets the horizontal scroll offset.
`int`	`scrollY` `const` `inline`	Gets the vertical scroll offset.
`void`	`setScroll`	Sets the scroll offset, clamped to the current content bounds.
`void`	`scrollBy`	Scrolls relative to the current position.
`bool`	`isFocusable` `virtual` `const` `inline`	Returns whether this widget can receive keyboard focus.
`core::Size`	`measure` `virtual`	Measures how much space this widget needs.
`void`	`layout` `virtual`	Positions and sizes this widget and its children.
`bool`	`onEvent` `virtual`	Handles an input event.
`std::vector< std::shared_ptr< Widget > >`	`getChildren` `virtual` `const` `inline`	Returns this widget’s children.
`std::vector< std::shared_ptr< Widget > >`	`getFocusChildren` `virtual` `const` `inline`	Returns this widget’s children for focus traversal.

ScrollView

ScrollView() = default

Defaulted constructor.

ScrollView

explicit

explicit ScrollView(std::shared_ptr< Widget > child)

setContent

void setContent(std::shared_ptr< Widget > child)

Sets the widget to display inside the scroll view.

Parameters

child The content widget to scroll, or nullptr to clear it

getContent

const inline

inline std::shared_ptr< Widget > getContent() const

Gets the current child widget.

Returns

The scroll view content, or nullptr if empty

setContentSize

void setContentSize(core::Size size)

Sets an explicit content size for the scrollable area.

Use this when the content widget’s natural measurement does not reflect its full scrollable size, such as when wrapping a container or layout. Passing 0 for a dimension auto-fills that dimension from the viewport.

Parameters

size The scrollable content size in cells

clearContentSize

void clearContentSize()

Clears any explicit content size and falls back to measure().

scrollX

const inline

inline int scrollX() const

Gets the horizontal scroll offset.

scrollY

const inline

inline int scrollY() const

Gets the vertical scroll offset.

setScroll

void setScroll(int x, int y)

Sets the scroll offset, clamped to the current content bounds.

scrollBy

void scrollBy(int dx, int dy)

Scrolls relative to the current position.

isFocusable

virtual const inline

virtual inline bool isFocusable() const

Returns whether this widget can receive keyboard focus.

Widgets like Button and Input return true; containers return false.

Returns

True if this widget can be focused, false otherwise

measure

virtual

virtual core::Size measure(int availW, int availH)

Measures how much space this widget needs.

Called during the measurement pass to determine widget size requirements. Should return the preferred size based on available space.

Parameters

availW Maximum available width (may be ignored by widget)
availH Maximum available height (may be ignored by widget)

Returns

The Size this widget wants, or needs at minimum

layout

virtual

virtual void layout(int x, int y, int width, int height)

Positions and sizes this widget and its children.

Called after measurement to actually place the widget at a specific location. If your widget has children, you must call their layout() methods here.

Parameters

x The X coordinate for this widget
y The Y coordinate for this widget
width The width allocated to this widget
height The height allocated to this widget

onEvent

virtual

virtual bool onEvent(const core::events::Event & event)

Handles an input event.

Called by the framework to deliver an event to this widget. The default implementation runs any listeners registered via addEventListener(), then returns false. Subclasses (Button, Input, etc.) override this to add built-in behavior, and should call Widget::onEvent(event) first to give user listeners a chance to handle the event before the widget’s own logic.

Return true if the event was handled, false to let it bubble to the parent widget.

Parameters

event The input event

Returns

True if this widget (or one of its listeners) handled the event

getChildren

virtual const inline

virtual inline std::vector< std::shared_ptr< Widget > > getChildren() const

Returns this widget’s children.

Returns

Vector of child widgets (empty if no children)

getFocusChildren

virtual const inline

virtual inline std::vector< std::shared_ptr< Widget > > getFocusChildren() const

Returns this widget’s children for focus traversal.

By default this matches getChildren(). Widgets with custom rendering behavior (like clipping/compositing) can override this without affecting paint traversal.

Protected Methods

Return	Name	Description
`void`	`drawContent` `virtual`	Draws this widget’s content.

drawContent

virtual

virtual void drawContent(backend::Buffer & buf, core::Rect inner)

Draws this widget’s content.

Called by render() after background and borders are drawn. This is where you should draw your widget’s actual content. The inner rectangle accounts for borders and padding.

Parameters

buf The buffer to draw to
inner The inner rectangle (excluding border/padding)

Private Attributes

Return	Name	Description
`std::shared_ptr< Widget >`	`content`
`bool`	`hasExplicitContentSize`
`core::Size`	`explicitContentSize`
`core::Size`	`currentContentSize`
`core::Rect`	`currentInner`
`bool`	`hasLayout`
`core::Pos`	`scroll`

content

std::shared_ptr< Widget > content

hasExplicitContentSize

bool hasExplicitContentSize = false

explicitContentSize

core::Size explicitContentSize {}

currentContentSize

core::Size currentContentSize {}

currentInner

core::Rect currentInner {}

hasLayout

bool hasLayout = false

scroll

core::Pos scroll {}

Private Methods

Return	Name	Description
`void`	`clampScroll`
`void`	`relayoutContent`
`core::Size`	`resolveContentSize` `const`

clampScroll

void clampScroll()

relayoutContent

void relayoutContent()

resolveContentSize

const

core::Size resolveContentSize(core::Rect inner) const