Struct CrawlParams 

pub struct CrawlParams {
    pub viewport_w: u32,
    pub viewport_h: u32,
    pub frame_hz: u32,
    pub pixels_per_sec: u32,
    pub line_spacing_px: u16,
    pub text_color_argb: u32,
    pub background_scroll_divisor: u16,
    pub perspective_top_width: u16,
    pub perspective_bottom_width: u16,
}

Common tuning parameters for a text-style scroll crawl.

Concrete presets (the disco-demo star crawl, a news ticker, …) fill these in. The platform crate doesn’t mandate a specific rendering style — only a shared shape so BSPs can treat crawls interchangeably and so rate / spacing / perspective tuning is lifted out of ad-hoc per-board constants.

The viewport_w / viewport_h fields describe the target rendering region — what the effect paints into — and are used by callers to size jumbo / text-source / scanline buffers before handing them to the factory. They are not consumed by the effect itself.

Fields

viewport_w: u32

Target viewport width in pixels.

viewport_h: u32

Target viewport height in pixels.

frame_hz: u32

Host frame rate in Hz. Effects use this together with pixels_per_sec to derive the per-frame scroll increment.

pixels_per_sec: u32

Declared wall-clock scroll speed, in pixels per second.

line_spacing_px: u16

Inter-line spacing in pixels for pre-rendered text.

text_color_argb: u32

Text colour in ARGB8888 byte order.

background_scroll_divisor: u16

Divider applied to the text scroll accumulator when sampling the background. 1 locks the background to the text; higher values create a parallax effect.

perspective_top_width: u16

Projected text width at the top edge of the viewport.

perspective_bottom_width: u16

Projected text width at the bottom edge of the viewport.

Implementations

impl CrawlParams

pub const fn star_crawl_disco( viewport_w: u32, viewport_h: u32, frame_hz: u32, ) -> Self

Disco-demo star-crawl defaults: 40 px/s upward scroll, 36 px line spacing, 360→600 px perspective taper, canonical yellow text, background drifting at 1/3 the text speed.

Matches the STM32H747I-DISCO hardware star crawl and the BBB Linux port. Hosts that want the sim-style looser spacing can mutate line_spacing_px after construction.

Trait Implementations

impl Clone for CrawlParams

fn clone(&self) -> CrawlParams

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for CrawlParams

impl Debug for CrawlParams

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

Formats the value using the given formatter.

impl Eq for CrawlParams

impl PartialEq for CrawlParams

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for CrawlParams