Media: Fix blurred thumb size (#5309)

src/hooks/useOffscreenCanvasBlur.ts

@@ -1,36 +1,54 @@
 import { useLayoutEffect, useMemo, useRef } from '../lib/teact/teact';
 
+import { requestMutation } from '../lib/fasterdom/fasterdom';
 import cycleRestrict from '../util/cycleRestrict';
+import { preloadImage } from '../util/files';
 import { MAX_WORKERS, requestMediaWorker } from '../util/launchMediaWorkers';
+import useLastCallback from './useLastCallback';
 
-const RADIUS = 7;
+const RADIUS_RATIO = 0.1; // Use 10% of the smallest dimension as the blur radius
 
 let lastWorkerIndex = -1;
 
 export default function useOffscreenCanvasBlur(
   thumbData?: string, // data URI or blob URL
   isDisabled = false,
-  radius = RADIUS,
 ) {
   // eslint-disable-next-line no-null/no-null
   const canvasRef = useRef<HTMLCanvasElement>(null);
   const workerIndex = useMemo(() => cycleRestrict(MAX_WORKERS, ++lastWorkerIndex), []);
   const offscreenRef = useRef<OffscreenCanvas>();
 
+  const blurThumb = useLastCallback(async (canvas: HTMLCanvasElement, uri: string) => {
+    const image = await preloadImage(uri);
+    if (!image) {
+      return;
+    }
+
+    requestMutation(() => {
+      canvas.width = image.width;
+      canvas.height = image.height;
+
+      offscreenRef.current = canvas.transferControlToOffscreen();
+
+      const radius = Math.ceil(Math.min(image.width, image.height) * RADIUS_RATIO);
+
+      requestMediaWorker({
+        name: 'offscreen-canvas:blurThumb',
+        args: [offscreenRef.current, uri, radius],
+        transferables: [offscreenRef.current],
+      }, workerIndex);
+    });
+  });
+
   useLayoutEffect(() => {
     if (!thumbData || isDisabled || offscreenRef.current) return;
 
     const canvas = canvasRef.current;
     if (!canvas) return;
 
-    offscreenRef.current = canvas.transferControlToOffscreen();
+    blurThumb(canvas, thumbData);
-
+  }, [blurThumb, isDisabled, thumbData]);
-    requestMediaWorker({
-      name: 'offscreen-canvas:blurThumb',
-      args: [offscreenRef.current, thumbData, radius],
-      transferables: [offscreenRef.current],
-    }, workerIndex);
-  }, [thumbData, isDisabled, radius, workerIndex]);
 
   return canvasRef;
 }