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Add background polling to resolve placeholder images #60

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Merged
hackall360 merged 1 commit into from
Sep 14, 2025
Merged

Add background polling to resolve placeholder images #60

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62 changes: 62 additions & 0 deletions js/ui/imagePoller.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,62 @@
import { image as polliImage } from '../polliLib/src/image.js';

let imageFn = polliImage;
let pollIntervalMs = 2000;
let timeoutMs = 20000;
let fallbackSrc = 'https://via.placeholder.com/512?text=Image+Unavailable';

const pending = new Map();
let timer = null;

export function trackPlaceholder(img, { prompt, model, width, height } = {}) {
if (!img) return;
pending.set(img, { prompt, model, width, height, start: Date.now() });
if (!timer) {
timer = setInterval(() => {
checkPending().catch(() => {});
}, pollIntervalMs);
}
}

async function checkPending() {
for (const [img, info] of pending) {
if (Date.now() - info.start > timeoutMs) {
img.src = fallbackSrc;
img.classList?.remove?.('placeholder');
pending.delete(img);
continue;
}
try {
const data = await imageFn(info.prompt, { model: info.model, width: info.width, height: info.height, json: true });
if (data && data.url) {
img.src = data.url;
img.classList?.remove?.('placeholder');
pending.delete(img);
}
} catch (err) {
img.src = fallbackSrc;
img.classList?.remove?.('placeholder');
pending.delete(img);
}
}
if (pending.size === 0 && timer) {
clearInterval(timer);
timer = null;
}
}

export function _setImageFn(fn) {
imageFn = fn;
}

export function _configure({ intervalMs, timeout, fallback } = {}) {
if (intervalMs != null) pollIntervalMs = intervalMs;
if (timeout != null) timeoutMs = timeout;
if (fallback != null) fallbackSrc = fallback;
if (timer) {
clearInterval(timer);
timer = setInterval(() => {
checkPending().catch(() => {});
}, pollIntervalMs);
}
}
31 changes: 31 additions & 0 deletions tests/site-image-poller.mjs
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Original file line number Diff line number Diff line change
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import assert from 'assert/strict';
import { trackPlaceholder, _configure, _setImageFn } from '../js/ui/imagePoller.js';

let calls = 0;
_setImageFn(async () => {
calls++;
if (calls === 1) return {}; // still pending
return { url: 'https://example.com/final.png' };
});

_configure({ intervalMs: 5, timeout: 100 });

const img = {
src: 'about:blank',
classList: {
set: new Set(['placeholder']),
remove(cls) { this.set.delete(cls); },
contains(cls) { return this.set.has(cls); }
}
};

trackPlaceholder(img, { prompt: 'test', model: 'foo' });

// wait long enough for two polling cycles
await new Promise(r => setTimeout(r, 30));
await new Promise(r => setTimeout(r, 30));

assert.equal(img.src, 'https://example.com/final.png');
assert.equal(img.classList.contains('placeholder'), false);

console.log('image-poller test passed');