From 851280fa847368c1f9c0e46e7523fa2ae3769864 Mon Sep 17 00:00:00 2001
From: kuuuube <hexagonisalie@gmail.com>
Date: Thu, 26 Dec 2024 17:53:46 -0500
Subject: [PATCH] Fix low quality image resizing

---
 ext/js/dictionary/dictionary-database.js       |  6 +++---
 ext/js/display/structured-content-generator.js | 10 +++++++++-
 types/ext/dictionary-database.d.ts             |  2 +-
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/ext/js/dictionary/dictionary-database.js b/ext/js/dictionary/dictionary-database.js
index 98347de52..5da2cd064 100644
--- a/ext/js/dictionary/dictionary-database.js
+++ b/ext/js/dictionary/dictionary-database.js
@@ -462,7 +462,7 @@ export class DictionaryDatabase {
                 } else {
                     const image = new Blob([m.content], {type: m.mediaType});
                     // eslint-disable-next-line no-undef
-                    await createImageBitmap(image).then((decodedImage) => {
+                    await createImageBitmap(image, {resizeWidth: m.canvasWidth, resizeHeight: m.canvasHeight, resizeQuality: 'high'}).then((decodedImage) => {
                         // we need to do a dumb hack where we convert this ImageBitmap to an ImageData by drawing it to a temporary canvas, because Firefox doesn't support transferring ImageBitmaps cross-process
                         const canvas = new OffscreenCanvas(decodedImage.width, decodedImage.height);
                         const ctx = canvas.getContext('2d');
@@ -815,9 +815,9 @@ export class DictionaryDatabase {
      * @param {import('dictionary-database').FindMultiBulkData<import('dictionary-database').DrawMediaGroupedRequest>} data
      * @returns {import('dictionary-database').DrawMedia}
      */
-    _createDrawMedia(row, {itemIndex: index, item: {canvasIndexes, canvasWidth, generation}}) {
+    _createDrawMedia(row, {itemIndex: index, item: {canvasIndexes, canvasWidth, canvasHeight, generation}}) {
         const {dictionary, path, mediaType, width, height, content} = row;
-        return {index, dictionary, path, mediaType, width, height, content, canvasIndexes, canvasWidth, generation};
+        return {index, dictionary, path, mediaType, width, height, content, canvasIndexes, canvasWidth, canvasHeight, generation};
     }
 
     /**
diff --git a/ext/js/display/structured-content-generator.js b/ext/js/display/structured-content-generator.js
index 0f83902a0..6ff8cf12f 100644
--- a/ext/js/display/structured-content-generator.js
+++ b/ext/js/display/structured-content-generator.js
@@ -131,7 +131,15 @@ export class StructuredContentGenerator {
             const image = this._contentManager instanceof DisplayContentManager ?
                 /** @type {HTMLCanvasElement} */ (this._createElement('canvas', 'gloss-image')) :
                 /** @type {HTMLImageElement} */ (this._createElement('img', 'gloss-image'));
-            image.width = width;
+            if (sizeUnits === 'em' && (hasPreferredWidth || hasPreferredHeight)) {
+                const emSize = 14; // We could Number.parseFloat(getComputedStyle(document.documentElement).fontSize); here for more accuracy but it would cause a layout and be extremely slow; possible improvement would be to calculate and cache the value
+                const scaleFactor = 2 * window.devicePixelRatio;
+                image.style.width = `${usedWidth}em`;
+                image.style.height = `${usedWidth * invAspectRatio}em`;
+                image.width = usedWidth * emSize * scaleFactor;
+            } else {
+                image.width = usedWidth;
+            }
             image.height = image.width * invAspectRatio;
 
             // Anki will not render images correctly without specifying to use 100% width and height
diff --git a/types/ext/dictionary-database.d.ts b/types/ext/dictionary-database.d.ts
index 69078c114..33aaf7ade 100644
--- a/types/ext/dictionary-database.d.ts
+++ b/types/ext/dictionary-database.d.ts
@@ -40,7 +40,7 @@ type MediaType = ArrayBuffer | string | null;
 
 export type Media<T extends MediaType = ArrayBuffer> = {index: number} & MediaDataBase<T>;
 
-export type DrawMedia<T extends MediaType = ArrayBuffer> = {index: number} & MediaDataBase<T> & {canvasWidth: number, canvasIndexes: number[], generation: number};
+export type DrawMedia<T extends MediaType = ArrayBuffer> = {index: number} & MediaDataBase<T> & {canvasWidth: number, canvasHeight: number, canvasIndexes: number[], generation: number};
 
 export type DatabaseTermEntry = {
     expression: string;