From acdafee6763b5a8acf3f5ca3d57aa81514008745 Mon Sep 17 00:00:00 2001
From: Michael Aufreiter <michael@letsken.com>
Date: Sat, 4 Apr 2026 23:36:39 +0200
Subject: [PATCH] Do resize via canvas, instead of @jsquash/resize

---
 package.json                      |  2 +-
 src/lib/client/asset_processor.js | 63 ++++++++++++++++++++-----------
 vite.config.js                    |  2 +-
 3 files changed, 43 insertions(+), 24 deletions(-)

diff --git a/package.json b/package.json
index 6d07e734..98bcb7bb 100644
--- a/package.json
+++ b/package.json
@@ -37,7 +37,7 @@
 		"vite": "^8.0.1"
 	},
 	"dependencies": {
-		"@jsquash/resize": "^2.1.1",
+
 		"@jsquash/webp": "^1.5.0",
 		"@sveltejs/adapter-node": "^5.5.4",
 		"nanoid": "^5.1.6",
diff --git a/src/lib/client/asset_processor.js b/src/lib/client/asset_processor.js
index 262de679..ee4e633d 100644
--- a/src/lib/client/asset_processor.js
+++ b/src/lib/client/asset_processor.js
@@ -1,5 +1,4 @@
 import { encode as encodeWebP } from '@jsquash/webp';
-import resize from '@jsquash/resize';
 
 const WEBP_QUALITY = 80;
 
@@ -20,6 +19,42 @@ async function decode_to_image_data(blob) {
 	return ctx.getImageData(0, 0, canvas.width, canvas.height);
 }
 
+/**
+ * Convert ImageData to a PNG blob using canvas.
+ *
+ * @param {ImageData} image_data
+ * @returns {Promise<Blob>}
+ */
+async function image_data_to_png_blob(image_data) {
+	const canvas = new OffscreenCanvas(image_data.width, image_data.height);
+	const ctx = canvas.getContext('2d');
+	if (!ctx) throw new Error('Could not get OffscreenCanvas 2d context');
+	ctx.putImageData(image_data, 0, 0);
+	return await canvas.convertToBlob({ type: 'image/png' });
+}
+
+/**
+ * Resize an image blob to a specific width using canvas, maintaining aspect ratio.
+ *
+ * @param {Blob} blob
+ * @param {number} target_width
+ * @returns {Promise<ImageData>}
+ */
+async function resize_blob_to_width(blob, target_width) {
+	const bitmap = await createImageBitmap(blob);
+	const scale = target_width / bitmap.width;
+	const target_height = Math.round(bitmap.height * scale);
+	const canvas = new OffscreenCanvas(target_width, target_height);
+	const ctx = canvas.getContext('2d');
+	if (!ctx) {
+		bitmap.close();
+		throw new Error('Could not get OffscreenCanvas 2d context');
+	}
+	ctx.drawImage(bitmap, 0, 0, target_width, target_height);
+	bitmap.close();
+	return ctx.getImageData(0, 0, target_width, target_height);
+}
+
 /**
  * Resize ImageData to fit within max_width, preserving aspect ratio.
  * Returns the original ImageData if it already fits.
@@ -29,19 +64,11 @@ async function decode_to_image_data(blob) {
  * @returns {Promise<ImageData>}
  */
 async function resize_to_fit(image_data, max_width) {
-	const { width, height } = image_data;
+	const { width } = image_data;
 	if (width <= max_width) return image_data;
 
-	const new_width = max_width;
-	const new_height = Math.round((height * max_width) / width);
-
-	return resize(image_data, {
-		width: new_width,
-		height: new_height,
-		method: 'lanczos3',
-		premultiply: true,
-		linearRGB: true
-	});
+	const png_blob = await image_data_to_png_blob(image_data);
+	return await resize_blob_to_width(png_blob, max_width);
 }
 
 /**
@@ -52,16 +79,8 @@ async function resize_to_fit(image_data, max_width) {
  * @returns {Promise<ImageData>}
  */
 async function resize_to_width(image_data, target_width) {
-	const scale = target_width / image_data.width;
-	const target_height = Math.round(image_data.height * scale);
-
-	return resize(image_data, {
-		width: target_width,
-		height: target_height,
-		method: 'lanczos3',
-		premultiply: true,
-		linearRGB: true
-	});
+	const png_blob = await image_data_to_png_blob(image_data);
+	return await resize_blob_to_width(png_blob, target_width);
 }
 
 /**
diff --git a/vite.config.js b/vite.config.js
index bc2534be..0d734c12 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -5,7 +5,7 @@ import { defineConfig } from 'vite';
 export default defineConfig({
 	plugins: [tailwindcss(), sveltekit()],
 	optimizeDeps: {
-		exclude: ['@jsquash/webp', '@jsquash/resize']
+		exclude: ['@jsquash/webp']
 	},
 	worker: {
 		format: 'es'