scroll

package
v0.6.3 Latest Latest
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 Go to latest Published: Jul 22, 2026 License: MIT Imports: 4 Imported by: 0

Documentation

Overview

Package scroll provides viewport and scrollbar primitives.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Controller 

type Controller interface {
	ScrollBy(dx, dy int)
	ScrollTo(x, y int)
	PageBy(pages int)
	ScrollToStart()
	ScrollToEnd()
}

Controller provides scroll control for widgets.

type FixedHeightIndex 

type FixedHeightIndex struct {
	Height int
	Count  func() int
}

FixedHeightIndex provides fast indexing for fixed-height items.

func (FixedHeightIndex) IndexForOffset 

func (f FixedHeightIndex) IndexForOffset(offset int) int

IndexForOffset returns the item index for a given offset.

func (FixedHeightIndex) OffsetForIndex 

func (f FixedHeightIndex) OffsetForIndex(index int) int

OffsetForIndex returns the offset for the given item index.

func (FixedHeightIndex) TotalHeight 

func (f FixedHeightIndex) TotalHeight() int

TotalHeight returns the total height for all items.

type Orientation 

type Orientation int

Orientation describes scrollbar orientation. 

const (
	Horizontal Orientation = iota
	Vertical
)

type ScrollBehavior 

type ScrollBehavior struct {
	Horizontal   ScrollPolicy
	Vertical     ScrollPolicy
	MouseWheel   int
	PageSize     float64
	SmoothScroll bool
}

ScrollBehavior controls scroll policies and interactions.

type ScrollPolicy 

type ScrollPolicy int

ScrollPolicy configures when scrollbars appear. 

const (
	ScrollAuto ScrollPolicy = iota
	ScrollAlways
	ScrollNever
)

type Scrollbar 

type Scrollbar struct {
	Orientation  Orientation
	Track        backend.Style
	Thumb        backend.Style
	MinThumbSize int
	Chars        ScrollbarChars
}

Scrollbar configures scrollbar rendering.

type ScrollbarChars 

type ScrollbarChars struct {
	Track rune
	Thumb rune
}

ScrollbarChars defines characters used to render the scrollbar.

func DefaultScrollbarChars 

func DefaultScrollbarChars() ScrollbarChars

DefaultScrollbarChars returns ASCII defaults.

type Viewport 

type Viewport struct {
	// contains filtered or unexported fields
}

Viewport tracks the visible region of scrollable content.

func NewViewport 

func NewViewport(content runtime.Widget) *Viewport

NewViewport creates a viewport.

func (*Viewport) Content 

func (v *Viewport) Content() runtime.Widget

Content returns the content widget.

func (*Viewport) ContentSize 

func (v *Viewport) ContentSize() runtime.Size

ContentSize returns the content size.

func (*Viewport) MaxOffset 

func (v *Viewport) MaxOffset() image.Point

MaxOffset returns the maximum scrollable offset.

func (*Viewport) Offset 

func (v *Viewport) Offset() image.Point

Offset returns the current offset.

func (*Viewport) PageBy 

func (v *Viewport) PageBy(pages int)

PageBy scrolls by a number of pages.

func (*Viewport) ScrollBy 

func (v *Viewport) ScrollBy(dx, dy int)

ScrollBy adjusts the offset.

func (*Viewport) ScrollTo 

func (v *Viewport) ScrollTo(x, y int)

ScrollTo scrolls to absolute coordinates.

func (*Viewport) ScrollToEnd 

func (v *Viewport) ScrollToEnd()

ScrollToEnd scrolls to the end of the content.

func (*Viewport) ScrollToStart 

func (v *Viewport) ScrollToStart()

ScrollToStart scrolls to the beginning of the content.

func (*Viewport) SetContent 

func (v *Viewport) SetContent(content runtime.Widget)

SetContent assigns the content widget.

func (*Viewport) SetContentSize 

func (v *Viewport) SetContentSize(size runtime.Size)

SetContentSize updates the content size and clamps the offset.

func (*Viewport) SetOffset 

func (v *Viewport) SetOffset(x, y int)

SetOffset sets the scroll offset.

func (*Viewport) SetOnChange 

func (v *Viewport) SetOnChange(fn func(offset image.Point, content runtime.Size, view runtime.Size))

SetOnChange sets a callback for offset updates.

func (*Viewport) SetViewSize 

func (v *Viewport) SetViewSize(size runtime.Size)

SetViewSize updates the view size and clamps the offset.

func (*Viewport) ViewSize 

func (v *Viewport) ViewSize() runtime.Size

ViewSize returns the view size.

func (*Viewport) VisibleRect 

func (v *Viewport) VisibleRect() runtime.Rect

VisibleRect returns the visible rectangle within content.

type VirtualContent 

type VirtualContent interface {
	ItemCount() int
	ItemHeight(index int) int
	RenderItem(index int, ctx runtime.RenderContext)
	ItemAt(index int) any
}

VirtualContent provides virtualized content rendering.

type VirtualHeightFunc 

type VirtualHeightFunc func(index int) int

VirtualHeightFunc returns the height for an item index.

type VirtualIndexer 

type VirtualIndexer interface {
	IndexForOffset(offset int) int
	OffsetForIndex(index int) int
}

VirtualIndexer optionally provides fast offset/index mapping.

type VirtualItemFunc 

type VirtualItemFunc func(index int) any

VirtualItemFunc returns the item data for an index.

type VirtualList 

type VirtualList struct {
	// contains filtered or unexported fields
}

VirtualList provides windowed calculations for large lists. It implements VirtualContent plus optional sizing and indexing helpers.

func NewVirtualList 

func NewVirtualList(itemCount int, itemHeight int, render VirtualRenderFunc) *VirtualList

NewVirtualList creates a virtual list with fixed item height.

func (*VirtualList) EnsureVisible 

func (v *VirtualList) EnsureVisible(index int)

EnsureVisible scrolls just enough to keep the item fully visible.

func (*VirtualList) GetVisibleRange 

func (v *VirtualList) GetVisibleRange() (start, end int)

GetVisibleRange returns the [start, end) item range for the current viewport, including overscan items.

func (*VirtualList) IndexForOffset 

func (v *VirtualList) IndexForOffset(offset int) int

IndexForOffset maps a scroll offset to an item index.

func (*VirtualList) InvalidateHeights 

func (v *VirtualList) InvalidateHeights()

InvalidateHeights clears cached height data for variable-height lists.

func (*VirtualList) ItemAt 

func (v *VirtualList) ItemAt(index int) any

ItemAt returns the item data at the given index.

func (*VirtualList) ItemCount 

func (v *VirtualList) ItemCount() int

ItemCount returns the item count.

func (*VirtualList) ItemHeight 

func (v *VirtualList) ItemHeight(index int) int

ItemHeight returns the height for the given item index.

func (*VirtualList) MaxOffset 

func (v *VirtualList) MaxOffset() int

MaxOffset returns the maximum scrollable offset.

func (*VirtualList) Offset 

func (v *VirtualList) Offset() int

Offset returns the current scroll offset.

func (*VirtualList) OffsetForIndex 

func (v *VirtualList) OffsetForIndex(index int) int

OffsetForIndex maps an item index to its scroll offset.

func (*VirtualList) RenderItem 

func (v *VirtualList) RenderItem(index int, ctx runtime.RenderContext)

RenderItem renders the item at index.

func (*VirtualList) ScrollBy 

func (v *VirtualList) ScrollBy(delta int)

ScrollBy scrolls the offset by the provided delta.

func (*VirtualList) ScrollToIndex 

func (v *VirtualList) ScrollToIndex(index int)

ScrollToIndex scrolls to the given item index.

func (*VirtualList) ScrollToOffset 

func (v *VirtualList) ScrollToOffset(pixels int)

ScrollToOffset scrolls to the given offset.

func (*VirtualList) SelectedIndex 

func (v *VirtualList) SelectedIndex() int

SelectedIndex returns the selected index.

func (*VirtualList) SetItemAt 

func (v *VirtualList) SetItemAt(fn VirtualItemFunc)

SetItemAt updates the item callback.

func (*VirtualList) SetItemCount 

func (v *VirtualList) SetItemCount(count int)

SetItemCount updates the item count and clamps offset/selection.

func (*VirtualList) SetItemHeight 

func (v *VirtualList) SetItemHeight(height int)

SetItemHeight sets a fixed item height.

func (*VirtualList) SetItemHeightFunc 

func (v *VirtualList) SetItemHeightFunc(fn VirtualHeightFunc)

SetItemHeightFunc sets a variable item height function.

func (*VirtualList) SetOnSelection 

func (v *VirtualList) SetOnSelection(fn func(index int))

SetOnSelection updates the selection callback.

func (*VirtualList) SetOverscan 

func (v *VirtualList) SetOverscan(count int)

SetOverscan updates the overscan item count.

func (*VirtualList) SetRenderItem 

func (v *VirtualList) SetRenderItem(fn VirtualRenderFunc)

SetRenderItem updates the render callback.

func (*VirtualList) SetSelected 

func (v *VirtualList) SetSelected(index int)

SetSelected updates the selected index.

func (*VirtualList) SetViewportHeight 

func (v *VirtualList) SetViewportHeight(height int)

SetViewportHeight updates the viewport height and clamps the offset.

func (*VirtualList) TotalHeight 

func (v *VirtualList) TotalHeight() int

TotalHeight returns the total height for all items.

type VirtualRenderFunc 

type VirtualRenderFunc func(index int, selected bool, ctx runtime.RenderContext)

VirtualRenderFunc renders an item at the given index.

type VirtualSizer 

type VirtualSizer interface {
	TotalHeight() int
}

VirtualSizer optionally provides total height for virtual content.

Source Files

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