@fluritheme/fluri/dist/rendering/Texture.js

Interactive snowfall for websites: DOM-aware snow accumulation, mouse interactions, snow physics, Canvas 2D rendering, and Christmas effects.

const maxSourceLength = 4 * 1024 * 1024;
/** Raster-only data URLs avoid SVG script/external-resource behavior. Remote images require HTTPS. */
export function isSafeTextureSource(value) {
    if (typeof value !== 'string' ||
        value.length === 0 ||
        value.length > maxSourceLength ||
        value !== value.trim())
        return false;
    if (/^data:image\/(?:png|jpeg|webp);base64,[a-z\d+/]+={0,2}$/i.test(value))
        return true;
    try {
        const url = new URL(value);
        if (url.username || url.password)
            return false;
        if (url.protocol === 'https:')
            return true;
        if (url.protocol === 'blob:') {
            if (/^blob:null\/[a-z\d-]+$/i.test(value))
                return true;
            const origin = new URL(value.slice(5));
            return (!origin.username &&
                !origin.password &&
                (origin.protocol === 'https:' || origin.protocol === 'http:'));
        }
    }
    catch {
        return false;
    }
    return false;
}
/** Owns exactly one asynchronous load. Stale callbacks cannot resurrect a disposed texture. */
export class SnowTexture {
    doc;
    onError;
    requested;
    pending;
    drawable;
    generation = 0;
    currentStatus = 'idle';
    constructor(doc, onError = () => { }) {
        this.doc = doc;
        this.onError = onError;
    }
    get status() {
        return this.currentStatus;
    }
    get image() {
        return this.drawable;
    }
    setSource(source) {
        if (this.currentStatus === 'destroyed' || this.requested === source)
            return;
        this.clearImage();
        this.requested = source;
        if (source === undefined) {
            this.currentStatus = 'idle';
            return;
        }
        if (!isSafeTextureSource(source)) {
            this.fail(new TypeError('Snow texture must be a safe HTTPS, blob, or raster data URL'));
            return;
        }
        const image = this.doc.createElement('img');
        const generation = this.generation;
        this.pending = image;
        this.currentStatus = 'loading';
        image.decoding = 'async';
        image.referrerPolicy = 'no-referrer';
        if (new URL(source).protocol === 'https:')
            image.crossOrigin = 'anonymous';
        image.onload = () => {
            if (generation !== this.generation || this.currentStatus === 'destroyed')
                return;
            if (image.naturalWidth <= 0 ||
                image.naturalHeight <= 0 ||
                image.naturalWidth > 2048 ||
                image.naturalHeight > 2048) {
                this.fail(new RangeError('Snow texture dimensions must be between 1 and 2048 pixels'));
                return;
            }
            image.onload = null;
            image.onerror = null;
            this.drawable = image;
            this.pending = undefined;
            this.currentStatus = 'ready';
        };
        image.onerror = () => {
            if (generation !== this.generation || this.currentStatus === 'destroyed')
                return;
            this.fail(new Error('Snow texture failed to load or was blocked by CORS or the site content security policy'));
        };
        image.src = source;
    }
    fail(error) {
        this.clearImage();
        this.currentStatus = 'error';
        this.onError(error);
    }
    clearImage() {
        this.generation++;
        for (const image of [this.pending, this.drawable])
            if (image) {
                image.onload = null;
                image.onerror = null;
                image.removeAttribute('src');
            }
        this.pending = undefined;
        this.drawable = undefined;
    }
    destroy() {
        if (this.currentStatus === 'destroyed')
            return;
        this.clearImage();
        this.requested = undefined;
        this.currentStatus = 'destroyed';
    }
}
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