github.com/gogpu/ui - core/listview/painter.go

func PaintDivider

PaintDivider draws a thin horizontal line at the divider bounds.

func (p DefaultPainter) PaintDivider(canvas widget.Canvas, ds DividerState) {
	if ds.Bounds.IsEmpty() {
		return
	}
	color := defaultDividerColor
	hasScheme := ds.ColorScheme != (ListColorScheme{})
	if hasScheme {
		color = ds.ColorScheme.DividerColor
	}
	canvas.DrawRect(ds.Bounds, color)
}

func PaintEmptyState

PaintEmptyState draws a centered "No items" message.

func (p DefaultPainter) PaintEmptyState(canvas widget.Canvas, bounds geometry.Rect) {
	if bounds.IsEmpty() {
		return
	}
	canvas.DrawText(emptyStateText, bounds, emptyStateFontSize, defaultEmptyTextColor, false, emptyStateAlign)
}

func PaintItemBackground

PaintItemBackground draws the background for a list item.

func (p DefaultPainter) PaintItemBackground(canvas widget.Canvas, ips ItemPaintState) {
	if ips.Bounds.IsEmpty() {
		return
	}
	hasScheme := ips.ColorScheme != (ListColorScheme{})
	if ips.Hovered && !ips.Disabled {
		color := defaultHoverColor
		if hasScheme {
			color = ips.ColorScheme.HoverColor
		}
		canvas.DrawRect(ips.Bounds, color)
	}
}

func PaintSelection

PaintSelection draws the selection highlight for a selected item.

func (p DefaultPainter) PaintSelection(canvas widget.Canvas, ips ItemPaintState) {
	if ips.Bounds.IsEmpty() || !ips.Selected {
		return
	}
	hasScheme := ips.ColorScheme != (ListColorScheme{})
	color := defaultSelectionColor
	if hasScheme {
		color = ips.ColorScheme.SelectionColor
	}
	canvas.DrawRect(ips.Bounds, color)

	// Draw focus border.
	if ips.Focused && !ips.Disabled {
		focusColor := defaultFocusBorderColor
		if hasScheme {
			focusColor = ips.ColorScheme.FocusColor
		}
		canvas.StrokeRect(ips.Bounds, focusColor, focusBorderWidth)
	}
}

type DividerState struct

DividerState provides context for divider painting.

type DividerState struct {
	// Bounds is the rectangle for the divider (full width, typically 1px height).
	Bounds	geometry.Rect

	// ItemIndex is the index of the item above the divider.
	ItemIndex	int

	// ColorScheme provides theme-derived colors.
	ColorScheme	ListColorScheme
}

type ItemPaintState struct

ItemPaintState provides context for item background and selection painting.

type ItemPaintState struct {
	// Bounds is the item's bounding rectangle.
	Bounds	geometry.Rect

	// Index is the item's zero-based index in the data source.
	Index	int

	// Selected is true if the item is selected.
	Selected	bool

	// Focused is true if the item has keyboard focus within the list.
	Focused	bool

	// Hovered is true if the mouse cursor is over this item.
	Hovered	bool

	// Disabled is true if the list is disabled.
	Disabled	bool

	// ColorScheme provides theme-derived colors.
	ColorScheme	ListColorScheme
}

type ListColorScheme struct

ListColorScheme provides theme-derived colors for list painting.

Zero value means the painter should use its built-in defaults.

type ListColorScheme struct {
	DividerColor		widget.Color	// divider line color
	SelectionColor		widget.Color	// selected item background
	HoverColor		widget.Color	// hovered item background
	FocusColor		widget.Color	// focused item border/background
	EmptyTextColor		widget.Color	// empty state text color
	ItemBackground		widget.Color	// alternating item background (even rows)
	ItemBackgroundAlt	widget.Color	// alternating item background (odd rows)
}

type DefaultPainter struct

DefaultPainter provides a minimal fallback painter with no design system styling.

It draws simple list visuals -- useful for testing and as a base reference.

type DefaultPainter struct{}

type Painter interface

Painter draws list-specific visual elements.

Each design system (Material 3, Fluent, Cupertino) provides its own

Painter implementation to render the list in its visual style.

If no Painter is set, the list view uses [DefaultPainter].

type Painter interface {
	// PaintDivider draws a divider line between items.
	PaintDivider(canvas widget.Canvas, state DividerState)

	// PaintEmptyState draws the empty state when ItemCount is 0.
	PaintEmptyState(canvas widget.Canvas, bounds geometry.Rect)

	// PaintItemBackground draws the background for a list item.
	// This is called before the item widget's own Draw method.
	PaintItemBackground(canvas widget.Canvas, state ItemPaintState)

	// PaintSelection draws the selection highlight for a selected item.
	// This is called before the item widget's own Draw method.
	PaintSelection(canvas widget.Canvas, state ItemPaintState)
}

core/listview/painter.go

Functions