Struct LayoutCallbackInfoRefData 

#[repr(C)]
pub struct LayoutCallbackInfoRefData<'a> {
    pub image_cache: &'a ImageCache,
    pub gl_context: &'a OptionGlContextPtr,
    pub system_fonts: &'a FcFontCache,
    pub system_style: Arc<SystemStyle>,
    pub active_route: Option<&'a RouteMatch>,
    pub monitors: MonitorVec,
    pub safe_area: SafeAreaInsets,
}

Gives the layout() function access to the RendererResources and the Window (for querying images and fonts, as well as width / height)

Reference data container for LayoutCallbackInfo (all read-only fields)

This struct consolidates all readonly references that layout callbacks need to query state. By grouping these into a single struct, we reduce the number of parameters to LayoutCallbackInfo::new() from 6 to 2, making the API more maintainable and easier to extend.

This is pure syntax sugar - the struct lives on the stack in the caller and is passed by reference.

Fields

image_cache: &'a ImageCache

Allows the layout() function to reference image IDs

gl_context: &'a OptionGlContextPtr

OpenGL context so that the layout() function can render textures

system_fonts: &'a FcFontCache

Reference to the system font cache

system_style: Arc<SystemStyle>

Platform-specific system style (colors, spacing, etc.) Used for CSD rendering and menu windows.

active_route: Option<&'a RouteMatch>

Active route match (if routing is configured). Contains the matched pattern and extracted parameters.

monitors: MonitorVec

#28 (d): SNAPSHOT of the system’s monitors, taken (locked + cloned) by the caller right before invoking the layout callback. A snapshot — not the live Arc<Mutex<…>> handle — because azul-core is no_std (no Mutex) and the list is read-only during a layout pass anyway. Lets layout() bound how much content it builds on first layout (e.g. at most monitor-height lines / monitor-area characters), so opening a huge file can never build an unbounded DOM.

safe_area: SafeAreaInsets

Safe-area insets: system bars, notch/cutout, and the on-screen keyboard’s height. Live values, not the platform defaults.

layout() needs these and could not reach them: they live on LayoutWindow and were exposed only through CallbackInfo, which is the EVENT callback. So an app could read the notch from a click handler and not from the function that decides where to draw — which is the one place it matters. A mobile app that must not draw under the status bar had no way to ask how tall it is.

Trait Implementations

impl<'a> Debug for LayoutCallbackInfoRefData<'a>

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

Formats the value using the given formatter.