Struct DynamicSelectorContext 

#[repr(C)]
pub struct DynamicSelectorContext {

    pub os: OsCondition,
    pub os_version: OsVersion,
    pub desktop_env: OptionLinuxDesktopEnv,
    pub de_version: u32,
    pub theme: ThemeCondition,
    pub media_type: MediaType,
    pub viewport_width: f32,
    pub viewport_height: f32,
    pub container_width: f32,
    pub container_height: f32,
    pub container_name: OptionString,
    pub prefers_reduced_motion: BoolCondition,
    pub prefers_high_contrast: BoolCondition,
    pub orientation: OrientationType,
    pub pseudo_state: PseudoStateFlags,
    pub language: AzString,
    pub window_focused: bool,
    pub safe_area_top: f32,
    pub safe_area_right: f32,
    pub safe_area_bottom: f32,
    pub safe_area_left: f32,
    pub keyboard_inset_height: f32,
}

Context for evaluating dynamic selectors

PartialEq is IMPLEMENTED MANUALLY (not derived): container_width / container_height use f32::NAN as the “no container” sentinel, and derived float equality makes NaN != NaN — so two identical contexts never compared equal, set_dynamic_selector_context’s early return never fired, and EVERY context set paid a full author restyle (~2-4 ms at document scale, measured by the media_restyle_cost workbench). The manual impl compares the f32 fields by bit pattern, which treats the NaN sentinel as equal to itself and is exactly the “did anything change” question this equality exists to answer.

Fields

os: OsCondition

Operating system info

os_version: OsVersion

desktop_env: OptionLinuxDesktopEnv

de_version: u32

Numeric version of the active desktop environment (0 = unknown). Used by @os(linux:gnome > 40) style selectors. A value of 0 never satisfies any DE-version constraint, so detection can be wired up later without breaking parsed rules.

theme: ThemeCondition

Theme info

media_type: MediaType

Media info (from WindowState)

viewport_width: f32

viewport_height: f32

container_width: f32

Container info (from parent node) NaN = no container

container_height: f32

container_name: OptionString

prefers_reduced_motion: BoolCondition

Accessibility preferences

prefers_high_contrast: BoolCondition

orientation: OrientationType

Orientation

pseudo_state: PseudoStateFlags

Node state (hover, active, focus, disabled, checked, focus_within, visited)

language: AzString

Language/Locale (BCP 47 tag, e.g., “en-US”, “de-DE”)

window_focused: bool

Whether the window currently has focus (for :backdrop pseudo-class) When false, :backdrop styles should be applied

safe_area_top: f32

The safe-area insets env(safe-area-inset-*) resolves against, in logical px. NaN = the platform reported NO inset for that edge, so an env() on it takes its fallback (or 0px without one) - the same “absent” sentinel container_width uses, compared by bit pattern in PartialEq below so an unchanged context still short-circuits the restyle. Fed from LayoutWindow::safe_area_insets (the shells’ single authority) via Self::with_safe_area; a rotation or a keyboard changes these, the context stops comparing equal, and the author cascade re-runs - which is how every env() value follows the live inset without any per-property invalidation.

safe_area_right: f32

safe_area_bottom: f32

safe_area_left: f32

keyboard_inset_height: f32

env(keyboard-inset-height): how much of the window the on-screen keyboard covers from the bottom (SafeAreaInsets::keyboard). NaN when no keyboard is up.

Implementations

impl DynamicSelectorContext

pub fn from_system_style(system_style: &SystemStyle) -> Self

Create a context from SystemStyle

pub fn with_safe_area(&self, insets: &SafeAreaInsets) -> Self

Carry the window’s live safe-area insets, so env(safe-area-inset-*) and env(keyboard-inset-height) resolve against them.

Each edge becomes its absolute pixel value; an edge the platform did not report (None) - or one carrying a relative unit, which no shell writes - becomes the NaN “absent” sentinel, so env() falls back.

pub fn with_viewport(&self, width: f32, height: f32) -> Self

Update viewport dimensions (e.g., on window resize)

pub fn with_container( &self, width: f32, height: f32, name: Option<AzString>, ) -> Self

Update container dimensions (for @container queries)

pub fn with_pseudo_state(&self, state: PseudoStateFlags) -> Self

Update pseudo-state (hover, active, focus, etc.)

pub fn viewport_breakpoint_changed( &self, other: &Self, breakpoints: &[f32], ) -> bool

Check if viewport changed significantly (for breakpoint detection)

Trait Implementations

impl Clone for DynamicSelectorContext

fn clone(&self) -> DynamicSelectorContext

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DynamicSelectorContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DynamicSelectorContext

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for DynamicSelectorContext

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.