Struct ChartMapping 

pub struct ChartMapping {
    pub rect: Rect,
    pub bar_spacing: f32,
    pub start_idx: usize,
    pub base_idx: usize,
    pub right_offset: f64,
    pub price: PriceMap,
}

Unified coordinate mapping for charts and indicator panes.

Converts between:

• Bar indices ↔ X screen coordinates
• Prices ↔ Y screen coordinates

Share the mapping with overlays and hit tests to keep them aligned with the pane.

Fields

rect: Rect

The chart rectangle (rendering area)

bar_spacing: f32

Spacing between bars in egui logical points.

start_idx: usize

Index of the first visible bar

base_idx: usize

Index of the final bar in the series, used as the horizontal anchor.

right_offset: f64

Right-side offset for chart scrolling (in bar units)

price: PriceMap

Price-to-y mapping of the pane; it carries its own vertical extent, which need not match rect

Implementations

impl ChartMapping

pub fn new( rect: Rect, bar_spacing: f32, start_idx: usize, base_idx: usize, right_offset: impl Into<f64>, price: PriceMap, ) -> Self

Create a new ChartMapping with all parameters.

pub fn idx_to_x(&self, bar_idx: usize) -> f32

Convert bar index to X screen coordinate.

This is the canonical formula used everywhere.

pub fn x_to_idx(&self, x: f32) -> usize

Convert X screen coordinate to bar index (inverse of idx_to_x).

A degenerate bar_spacing (zero or sub-epsilon) has no inverse, so the anchor index is returned rather than producing an infinite/NaN index.

pub fn x_to_idx_f32(&self, x: f32) -> f32

Convert X screen coordinate to fractional bar index.

Useful for precise positioning (e.g., crosshair snapping).

A degenerate bar_spacing (zero or sub-epsilon) has no inverse, so the anchor index is returned rather than producing an infinite/NaN index.

pub fn x_to_idx_f64(&self, x: f32) -> f64

Convert X to a fractional bar index, retaining sub-bar precision on large histories. A degenerate spacing returns the anchor, as in Self::x_to_idx_f32.

pub fn is_x_visible(&self, x: f32) -> bool

Check if an X coordinate is within the visible chart bounds.

pub fn local_idx_at_x(&self, x: f32, visible_len: usize) -> Option<usize>

Resolve the bar directly under a cursor X coordinate to a local index into the visible data slice of length visible_len.

Returns None when there is no data, or when the cursor falls before the first bar or after the last bar (the right-side empty scroll margin), so callers never index past the slice or read a stale neighbour. Resolution uses Self::x_to_idx_f64, the exact inverse of Self::idx_to_x, so the bar at its own centre x resolves to itself and the readout describes the same bar the crosshair snaps to.

pub fn bar_width(&self) -> f32

Calculate the bar width based on spacing.

pub fn price_to_y(&self, price: f64) -> f32

Convert price to Y screen coordinate.

pub fn y_to_price(&self, y: f32) -> f64

Convert Y screen coordinate to price (inverse of price_to_y).

pub fn is_y_visible(&self, y: f32) -> bool

Check if a Y coordinate is within the visible chart bounds.

pub fn to_screen(&self, bar_idx: usize, price: f64) -> Pos2

Convert bar index and price to screen position.

pub fn from_screen(&self, pos: Pos2) -> (usize, f64)

Convert screen position to bar index and price.

pub fn is_visible(&self, pos: Pos2) -> bool

Check if a screen position is within the visible chart bounds.

pub fn with_rect(self, rect: Rect) -> Self

Create a new ChartMapping with a different rect (for sub-regions).

Only the x mapping and the bounds checks follow the new rect: price still maps onto its own pane.

Trait Implementations

impl Clone for ChartMapping

fn clone(&self) -> ChartMapping

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ChartMapping

impl Debug for ChartMapping

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

Formats the value using the given formatter.