Crate plotkit_render_wasm

Expand description

WASM Canvas2D rendering backend for plotkit.

This crate provides WasmRenderer, a rendering backend that translates plotkit drawing primitives into HTML5 Canvas2D API calls via web-sys. It is designed to run in WebAssembly environments inside a browser.

§Architecture

The renderer wraps a CanvasRenderingContext2d obtained from an HtmlCanvasElement. Each plotkit primitive (path fill, path stroke, text draw, clipping, image blit) maps directly to the corresponding Canvas2D method calls.

Helper functions for color conversion, font string construction, and affine transform decomposition are exposed as pure functions so they can be unit-tested without a browser environment.

§Example (browser-side)

use plotkit_render_wasm::WasmRenderer;
use web_sys::CanvasRenderingContext2d;

let ctx: CanvasRenderingContext2d = /* obtain from canvas element */;
let mut renderer = WasmRenderer::new(ctx, 800, 600);
// ... use renderer via the Renderer trait ...
let _ = renderer.finalize();

Structs§

Affine: A 2D affine transform.
Color: An RGBA color with 8 bits per channel.
DashPattern: A repeating dash pattern for stroked paths.
Image: A raster image stored as raw RGBA pixel data.
Paint: Describes how a filled region should be painted.
Path: A vector path composed of a sequence of PathEl elements.
Point: A 2D point in device-independent coordinates.
Rect: An axis-aligned rectangle defined by its top-left corner and dimensions.
Stroke: Describes the visual style of a stroked path.
TextStyle: Controls how text is rendered: size, color, weight, font, and alignment.

Enums§

FontWeight: Font weight selector.
HAlign: Horizontal text alignment.
PathEl: A single element within a Path.
StrokeCap: The shape applied at the endpoints of an open sub-path.
StrokeJoin: The shape applied at the join between two path segments.
VAlign: Vertical text alignment.

Traits§

Renderer: A rendering backend that can produce raster or vector output.

Functions§

affine_to_canvas_params: Decomposes a plotkit Affine transform into the six parameters expected by CanvasRenderingContext2d.setTransform(a, b, c, d, e, f).
build_font_string: Builds a CSS font shorthand string from a TextStyle.
color_to_css: Converts a plotkit Color to a CSS rgba(...) string.
count_path_elements: Counts the number of each path element type in a Path.
dash_pattern_values: Computes a dash pattern array string suitable for Canvas2D setLineDash.
estimate_text_width: Estimates the width of a text string for a given TextStyle.
halign_to_canvas: Returns the Canvas2D textAlign property value for a given HAlign.
stroke_cap_to_canvas: Returns the Canvas2D lineCap property value for a given StrokeCap.
stroke_join_to_canvas: Returns the Canvas2D lineJoin property value for a given StrokeJoin.
valign_to_canvas: Returns the Canvas2D textBaseline property value for a given VAlign.