Struct RenderContext 

pub struct RenderContext<'a> {
    pub buffer: &'a mut Buffer,
    pub area: Rect,
    pub style: Option<&'a Style>,
    pub state: Option<&'a NodeState>,
    /* private fields */
}

Render context passed to widgets

Fields

buffer: &'a mut Buffer

Buffer to render into

area: Rect

Available area for rendering

style: Option<&'a Style>

Computed style from CSS cascade

state: Option<&'a NodeState>

Current widget state

Implementations

impl<'a> RenderContext<'a>

pub fn new(buffer: &'a mut Buffer, area: Rect) -> Self

Create a basic render context (without style/state)

pub fn with_style(buffer: &'a mut Buffer, area: Rect, style: &'a Style) -> Self

Create a render context with style

pub fn full( buffer: &'a mut Buffer, area: Rect, style: &'a Style, state: &'a NodeState, ) -> Self

Create a full render context

pub fn with_transitions(self, transitions: &'a HashMap<String, f32>) -> Self

Set transition values for this render context

pub fn transition(&self, property: &str) -> Option<f32>

Get current transition value for a property

Returns the interpolated value during animation, or None if no transition is active. Use this to animate properties like opacity, position offsets, etc.

Example

let opacity = ctx.transition("opacity").unwrap_or(1.0);

pub fn transition_or(&self, property: &str, default: f32) -> f32

Get transition value with a default fallback

pub fn is_focused(&self) -> bool

Check if focused

pub fn is_hovered(&self) -> bool

Check if hovered

pub fn is_disabled(&self) -> bool

Check if disabled

pub fn draw_char(&mut self, x: u16, y: u16, ch: char, fg: Color)

Draw a single character at position

pub fn draw_char_bg(&mut self, x: u16, y: u16, ch: char, fg: Color, bg: Color)

Draw a character with background color

pub fn draw_char_bold(&mut self, x: u16, y: u16, ch: char, fg: Color)

Draw a bold character

pub fn draw_text(&mut self, x: u16, y: u16, text: &str, fg: Color)

Draw text at position

pub fn draw_text_bg(&mut self, x: u16, y: u16, text: &str, fg: Color, bg: Color)

Draw text with background color

pub fn draw_text_bold(&mut self, x: u16, y: u16, text: &str, fg: Color)

Draw bold text

pub fn draw_hline(&mut self, x: u16, y: u16, len: u16, ch: char, fg: Color)

Draw a horizontal line

pub fn draw_vline(&mut self, x: u16, y: u16, len: u16, ch: char, fg: Color)

Draw a vertical line

pub fn draw_box_rounded(&mut self, x: u16, y: u16, w: u16, h: u16, fg: Color)

Draw a box with rounded corners

pub fn draw_box_no_top(&mut self, x: u16, y: u16, w: u16, h: u16, fg: Color)

Draw a box without top border (for custom multi-color headers)

Use this when you want to draw your own header line with multiple colors. The caller should draw the complete top line including corners.

pub fn draw_header_line( &mut self, x: u16, y: u16, width: u16, parts: &[(&str, Color)], border_color: Color, )

Draw a complete header line with corners for use with draw_box_no_top

Draws: ╭─ [content parts with colors] ─────╮

Arguments

• x, y - Position of header line
• width - Total width including corners
• parts - Content parts as (text, color) pairs
• border_color - Color for corners and fill dashes

Example

ctx.draw_box_no_top(x, y, width, height, BLUE);
ctx.draw_header_line(x, y, width, &[
    (" 5 jobs ", BLUE),
    ("│", FG_DIM),
    (" ✓ 3 ", GREEN),
], BLUE);

pub fn draw_box_single(&mut self, x: u16, y: u16, w: u16, h: u16, fg: Color)

Draw a box with single border

pub fn draw_box_double(&mut self, x: u16, y: u16, w: u16, h: u16, fg: Color)

Draw a box with double border

pub fn fill(&mut self, x: u16, y: u16, w: u16, h: u16, ch: char, fg: Color)

Fill a rectangular area with a character

pub fn fill_bg(&mut self, x: u16, y: u16, w: u16, h: u16, bg: Color)

Fill with background color

pub fn clear(&mut self, x: u16, y: u16, w: u16, h: u16)

Clear area (fill with spaces)

pub fn draw_text_clipped( &mut self, x: u16, y: u16, text: &str, fg: Color, max_width: u16, )

Draw text clipped to max_width (stops drawing at boundary)

pub fn draw_text_clipped_bold( &mut self, x: u16, y: u16, text: &str, fg: Color, max_width: u16, )

Draw bold text clipped to max_width

pub fn draw_text_dim(&mut self, x: u16, y: u16, text: &str, fg: Color)

Draw dimmed text

pub fn draw_text_italic(&mut self, x: u16, y: u16, text: &str, fg: Color)

Draw italic text

pub fn draw_text_underline(&mut self, x: u16, y: u16, text: &str, fg: Color)

Draw underlined text

pub fn draw_text_centered( &mut self, x: u16, y: u16, width: u16, text: &str, fg: Color, )

Draw text centered within a given width

pub fn draw_text_right( &mut self, x: u16, y: u16, width: u16, text: &str, fg: Color, )

Draw text right-aligned within a given width

pub fn draw_box_titled( &mut self, x: u16, y: u16, w: u16, h: u16, title: &str, fg: Color, )

Draw a rounded box with a title on the top border

pub fn draw_box_titled_single( &mut self, x: u16, y: u16, w: u16, h: u16, title: &str, fg: Color, )

Draw a single-line box with a title

pub fn draw_box_titled_double( &mut self, x: u16, y: u16, w: u16, h: u16, title: &str, fg: Color, )

Draw a double-line box with a title

pub fn draw_progress_bar(&mut self, config: &ProgressBarConfig)

Draw a horizontal progress bar

Draw a progress bar with custom characters

pub fn draw_progress_bar_labeled( &mut self, x: u16, y: u16, bar_width: u16, progress: f32, fg: Color, )

Draw a progress bar with percentage label

pub fn draw_segments( &mut self, x: u16, y: u16, segments: &[(&str, Color)], ) -> u16

Draw multiple text segments with different colors on one line

Returns the ending x position for chaining.

Example

ctx.draw_segments(x, y, &[
    ("●", Color::GREEN),
    (" 3/5 ", Color::WHITE),
    ("mounted", Color::CYAN),
]);

pub fn draw_segments_sep( &mut self, x: u16, y: u16, segments: &[(&str, Color)], sep: &str, sep_color: Color, ) -> u16

Draw segments with a separator between them

pub fn draw_key_hints( &mut self, x: u16, y: u16, hints: &[(&str, &str)], key_color: Color, action_color: Color, ) -> u16

Draw key hints (key in bold color, action in dim)

Example

ctx.draw_key_hints(x, y, &[("j/k", "Move"), ("m", "Mount")], Color::CYAN, Color::GRAY);

pub fn draw_text_selectable( &mut self, x: u16, y: u16, text: &str, selected: bool, normal_color: Color, selected_color: Color, )

Draw text with selection styling (bold + highlight color when selected)

pub fn metric_color( value: u8, mid: u8, high: u8, low_color: Color, mid_color: Color, high_color: Color, ) -> Color

Get color based on value thresholds (for metrics)

Returns low_color if value < mid, mid_color if value < high, else high_color

pub fn css_color(&self, default: Color) -> Color

Get foreground color from CSS style or use default

This is the primary method for widgets to get their foreground color when CSS styling is enabled. It checks the computed CSS style first, falling back to the provided default.

Example

let fg = ctx.css_color(Color::WHITE);

pub fn css_background(&self, default: Color) -> Color

Get background color from CSS style or use default

pub fn css_border_color(&self, default: Color) -> Color

Get border color from CSS style or use default

pub fn css_opacity(&self) -> f32

Get opacity from CSS style (1.0 = fully opaque)

pub fn css_visible(&self) -> bool

Check if visible according to CSS

pub fn css_padding(&self) -> Spacing

Get padding from CSS style

pub fn css_margin(&self) -> Spacing

Get margin from CSS style

pub fn css_width(&self) -> Size

Get width from CSS style

pub fn css_height(&self) -> Size

Get height from CSS style

pub fn css_border_style(&self) -> BorderStyle

Get border style from CSS

pub fn css_gap(&self) -> u16

Get gap from CSS style (for flex/grid layouts)

pub fn resolve_fg( &self, widget_override: Option<Color>, default: Color, ) -> Color

Resolve effective foreground color considering CSS, widget state, and disabled state

Priority order:

1. Disabled state (returns DISABLED_FG)
2. Widget state override (if provided)
3. CSS computed style
4. Default fallback

Example

let fg = ctx.resolve_fg(widget.state.effective_fg_opt(), Color::WHITE);

pub fn resolve_bg( &self, widget_override: Option<Color>, default: Color, ) -> Color

Resolve effective background color considering CSS, widget state, and disabled state

pub fn draw_focus_ring( &mut self, x: u16, y: u16, w: u16, h: u16, color: Color, style: FocusStyle, )

Draw a focus ring around an area

This draws a visible focus indicator around the given bounds. Use this when the widget has focus to provide visual feedback.

Arguments

• x, y - Top-left corner of the focused area
• w, h - Width and height of the focused area
• color - Color of the focus ring
• style - Style of the focus ring

Example

if ctx.is_focused() {
    ctx.draw_focus_ring(x, y, w, h, Color::CYAN, FocusStyle::Dotted);
}

pub fn draw_focus_ring_auto( &mut self, x: u16, y: u16, w: u16, h: u16, color: Color, )

Draw a focus ring with automatic style based on context

Uses bold style for high-contrast mode, rounded for normal mode.

pub fn draw_focus_underline(&mut self, x: u16, y: u16, w: u16, color: Color)

Draw a focus underline (for inline elements)

Draws an underline under the focused element.

pub fn draw_focus_marker(&mut self, x: u16, y: u16, color: Color)

Draw a focus indicator at a specific position

Draws a small marker (like ▶) to indicate focus.

pub fn draw_focus_marker_left(&mut self, y: u16, color: Color)

Draw a focus indicator on the left side of an item

Common pattern for list items - shows a marker when focused.

pub fn invert_colors(&mut self, x: u16, y: u16, w: u16, h: u16)

Invert colors in a region (for high contrast focus indication)

Swaps foreground and background colors in the specified area.

pub fn draw_focus_reverse(&mut self, x: u16, y: u16, w: u16, h: u16)

Add reverse video effect to indicate focus

Applies reverse video (swapped fg/bg colors) to the area.