Module: ui.widgets.panel

Source: ./ui/widgets/panel.reef

Overview

ui/widgets/panel.reef - Container widget with background Part of reef-stdlib UI module

The Panel widget is a container that provides a background, border, and optional padding for its child content. It's used to group related UI elements visually.

Panels support:

Background colors (solid or from theme)
Borders with configurable width and radius
Padding around content
Shadow effects (visual depth)

Types

PanelStyle (enum)

Variants:

Flat
Raised
Sunken
Outlined
Card

Objects

Panel

Extends: widget.Widget

Fields:

Name	Type
`style`	`PanelStyle`
`padding_top`	`float`
`padding_right`	`float`
`padding_bottom`	`float`
`padding_left`	`float`
`custom_background`	`core.Color`
`use_custom_background`	`bool`
`border_width`	`float`
`border_radius`	`float`
`kids`	`[widget.Widget]`

`proc init(id: widget.WidgetId)`

Methods:

`override shared fn kind(): string`

`exclusive proc add(child: widget.Widget)`

`override exclusive proc paint(surf: surface.Surface, th: theme.Theme)`

`exclusive proc set_style(style: PanelStyle)`

`exclusive proc set_padding(padding: float)`

`exclusive proc set_padding_each(top: float, right: float, bottom: float, left: float)`

`exclusive proc set_background(color: core.Color)`

`exclusive proc set_border_width(width: float)`

`exclusive proc set_border_radius(radius: float)`

`shared fn clone(): Panel`

D2 (docs/design/2026-09-08-ui-modernization.md): a SHALLOW copy. Setters mutate the receiver (reef-lang#62), so "give me a variant and leave the original alone" has to be asked for explicitly. Referenced objects are shared, not deep-copied. The kids array is copied element-wise: append allocates a fresh array, but an element store through the clone would otherwise reach the original's array. The child widgets are shared references, deliberately.

`shared fn preferred_size(content_size: core.Size): core.Size`

`exclusive proc layout(constraints: layout.Constraints)`

`override exclusive fn handle_event(e: event.Event): widget.EventResult`

Functions

`fn panel_style_flat(): PanelStyle`

`fn panel_style_raised(): PanelStyle`

`fn panel_style_sunken(): PanelStyle`

`fn panel_style_outlined(): PanelStyle`

`fn panel_style_card(): PanelStyle`

`fn is_panel_flat(s: PanelStyle): bool`

`fn is_panel_raised(s: PanelStyle): bool`

`fn is_panel_sunken(s: PanelStyle): bool`

`fn is_panel_outlined(s: PanelStyle): bool`

`fn is_panel_card(s: PanelStyle): bool`

`fn panel(): Panel`

`fn panel_with_style(style: PanelStyle): Panel`

`fn panel_with_padding(padding: float): Panel`

`fn panel_child_count(p: Panel): int`

`fn panel_padding(p: Panel): float`

`fn panel_content_bounds(p: Panel): core.Rect`

`fn get_panel_background(p: Panel, colors: theme.ThemeColors): core.Color`

`fn get_panel_border_color(p: Panel, colors: theme.ThemeColors): core.Color`

Procedures

`proc panel_add(p: Panel, child: widget.Widget)`

`proc draw_shadow(surf: surface.Surface, x: float, y: float, w: float, h: float, offset: float)`

`proc draw_raised_border(surf: surface.Surface, x: float, y: float, w: float, h: float, colors: theme.ThemeColors)`

`proc draw_sunken_border(surf: surface.Surface, x: float, y: float, w: float, h: float, colors: theme.ThemeColors)`

`proc draw_rect_border(surf: surface.Surface, x: float, y: float, w: float, h: float, color: core.Color, width: float)`

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