Fix/double page mode not aborting preload image requests

src/components/reader/DoublePage.tsx

@@ -6,7 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { forwardRef, useRef } from 'react';
+import { forwardRef } from 'react';
 import { Box, SxProps, Theme } from '@mui/material';
 import { IReaderSettings } from '@/typings';
 import { SpinnerImage } from '@/components/util/SpinnerImage';
@@ -23,7 +23,6 @@ interface IProps {
 export const DoublePage = forwardRef((props: IProps, ref: any) => {
     const { image1src, image2src, index, onImageLoad, settings } = props;
 
-    const imgRef = useRef<HTMLImageElement>(null);
     const baseImgStyle = imageStyle(settings);
     const imgStyle = {
         ...baseImgStyle,
@@ -56,15 +55,13 @@ export const DoublePage = forwardRef((props: IProps, ref: any) => {
                 src={image1src}
                 onImageLoad={onImageLoad}
                 alt={`Page #${index}`}
-                imgRef={imgRef}
                 spinnerStyle={spinnerStyle}
                 imgStyle={{ ...imgStyle, objectPosition: settings.readerType === 'DoubleLTR' ? 'right' : 'left' }}
             />
             <SpinnerImage
                 src={image2src}
                 onImageLoad={onImageLoad}
                 alt={`Page #${index + 1}`}
-                imgRef={imgRef}
                 spinnerStyle={{
                     ...spinnerStyle,
                     width: 'calc(50% - 5px)',

src/components/reader/Page.tsx

@@ -6,7 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { forwardRef, useRef } from 'react';
+import { forwardRef } from 'react';
 import Box from '@mui/material/Box';
 import { useTheme } from '@mui/material/styles';
 import { useMediaQuery } from '@mui/material';
@@ -67,8 +67,6 @@ export const Page = forwardRef((props: IProps, ref: any) => {
     const theme = useTheme();
     const isMobileWidth = useMediaQuery(theme.breakpoints.down('md'));
 
-    const imgRef = useRef<HTMLImageElement>(null);
-
     const imgStyle = imageStyle(settings);
     const isDoublePageReader = ['DoubleRTL', 'DoubleLTR'].includes(settings.readerType);
 
@@ -87,7 +85,6 @@ export const Page = forwardRef((props: IProps, ref: any) => {
                 src={src}
                 onImageLoad={onImageLoad}
                 alt={`Page #${index}`}
-                imgRef={imgRef}
                 spinnerStyle={{
                     ...imgStyle,
                     height: '100vh',

src/components/reader/pager/DoublePagedPager.tsx

@@ -11,6 +11,7 @@ import { Box } from '@mui/material';
 import { IReaderProps } from '@/typings';
 import { Page } from '@/components/reader/Page';
 import { DoublePage } from '@/components/reader/DoublePage';
+import { requestManager } from '@/lib/requests/RequestManager.ts';
 
 const isSpreadPage = (image: HTMLImageElement): boolean => {
     const aspectRatio = image.height / image.width;
@@ -29,23 +30,22 @@ const isSinglePage = (index: number, spreadPages: boolean[], offsetFirstPage: bo
 };
 
 export function DoublePagedPager(props: IReaderProps) {
-    const { pages, settings, setCurPage, initialPage, curPage, nextChapter, prevChapter } = props;
+    const { pages, settings, setCurPage, initialPage, curPage, chapter, nextChapter, prevChapter } = props;
 
     const selfRef = useRef<HTMLDivElement>(null);
-    const pagesRef = useRef<HTMLImageElement[]>([]);
 
     const [pagesToSpreadState, setPagesToSpreadState] = useState(Array(pages.length).fill(false));
     const [pagesLoadState, setPagesLoadState] = useState<boolean[]>(Array(pages.length).fill(false));
 
     function getPagesToDisplay(): number {
         let pagesToDisplay = 1; // has to be at least one so skipping forward while pages are still loading is possible
-        if (curPage < pages.length && pagesRef.current[curPage]) {
+        if (curPage < pages.length) {
             if (pagesLoadState[curPage]) {
                 pagesToDisplay = 1;
                 if (pagesToSpreadState[curPage]) return pagesToDisplay;
             }
         }
-        if (curPage + 1 < pages.length && pagesRef.current[curPage + 1]) {
+        if (curPage + 1 < pages.length) {
             if (pagesLoadState[curPage + 1]) {
                 if (isSinglePage(curPage, pagesToSpreadState, settings.offsetFirstPage)) return pagesToDisplay;
                 pagesToDisplay = 2;
@@ -124,14 +124,6 @@ export function DoublePagedPager(props: IReaderProps) {
         }
     }
 
-    function handleImageLoad(index: number) {
-        return () => {
-            setPagesLoadState((prevState) => prevState.toSpliced(index, 1, true));
-            const image = pagesRef.current[index];
-            setPagesToSpreadState((prevState) => prevState.toSpliced(index, 1, isSpreadPage(image)));
-        };
-    }
-
     useEffect(() => {
         document.addEventListener('keydown', keyboardControl);
 
@@ -154,21 +146,37 @@ export function DoublePagedPager(props: IReaderProps) {
         }
     }, [settings.offsetFirstPage]);
 
+    useEffect(() => {
+        const imageRequests: [number, ReturnType<(typeof requestManager)['requestImage']>][] = pages.map((page) => [
+            page.index,
+            requestManager.requestImage(page.src),
+        ]);
+
+        imageRequests.forEach(async ([index, imageRequest]) => {
+            try {
+                const imageUrl = await imageRequest.response;
+                const img = new Image();
+                img.onload = () => {
+                    URL.revokeObjectURL(imageUrl);
+
+                    setPagesLoadState((prevState) => prevState.toSpliced(index, 1, true));
+                    setPagesToSpreadState((prevState) => prevState.toSpliced(index, 1, isSpreadPage(img)));
+                };
+                img.src = imageUrl;
+            } catch (e) {
+                // ignore
+            }
+        });
+
+        return () => {
+            imageRequests.forEach(([index, imageRequest]) =>
+                imageRequest.abortRequest(new Error(`DoublePagedPager::preload(${index}): chapter changed`)),
+            );
+        };
+    }, [chapter.id]);
+
     return (
         <Box ref={selfRef} onClick={clickControl}>
-            <Box id="preload" sx={{ display: 'none' }}>
-                {pages.map((page) => (
-                    <img
-                        ref={(e: HTMLImageElement) => {
-                            pagesRef.current[page.index] = e;
-                        }}
-                        key={`${page.index}`}
-                        src={page.src}
-                        onLoad={handleImageLoad(page.index)}
-                        alt={`${page.index}`}
-                    />
-                ))}
-            </Box>
             <Box
                 id="display"
                 sx={{

src/components/util/SpinnerImage.tsx

@@ -6,7 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import React, { useState, CSSProperties, useEffect } from 'react';
+import { useState, CSSProperties, useEffect, forwardRef, ForwardedRef } from 'react';
 import CircularProgress from '@mui/material/CircularProgress';
 import Box from '@mui/material/Box';
 import { Theme, SxProps, Stack, Button } from '@mui/material';
@@ -22,16 +22,14 @@ interface IProps {
     src: string;
     alt: string;
 
-    imgRef?: React.RefObject<HTMLImageElement>;
-
     spinnerStyle?: SxProps<Theme>;
     imgStyle?: CSSProperties;
 
     onImageLoad?: () => void;
 }
 
-export function SpinnerImage(props: IProps) {
-    const { src, alt, onImageLoad, imgRef, spinnerStyle, imgStyle } = props;
+export const SpinnerImage = forwardRef((props: IProps, imgRef: ForwardedRef<HTMLImageElement | null>) => {
+    const { src, alt, onImageLoad, spinnerStyle, imgStyle } = props;
 
     const { t } = useTranslation();
 
@@ -118,16 +116,10 @@ export function SpinnerImage(props: IProps) {
                 }}
                 ref={imgRef}
                 src={imageSourceUrl}
+                onLoad={() => URL.revokeObjectURL(imageSourceUrl)}
                 alt={alt}
                 draggable={false}
             />
         </>
     );
-}
-
-SpinnerImage.defaultProps = {
-    spinnerStyle: {},
-    imgStyle: {},
-    onImageLoad: () => {},
-    imgRef: undefined,
-};
+});

src/lib/requests/RequestManager.ts

@@ -746,6 +746,19 @@ export class RequestManager {
         return `${this.getValidUrlFor(imageUrl, apiVersion)}`;
     }
 
+    /**
+     * After the image has been handled, {@see URL#revokeObjectURL} has to be called.
+     *
+     * @example
+     *
+     * const imageRequest = requestManager.requestImage("someUrl");
+     * const imageUrl = await imageRequest.response
+     *
+     * const img = new Image();
+     * img.onLoad = () => URL.revokeObjectURL(imageUrl);
+     * img.src = imageUrl;
+     *
+     */
     public requestImage(url: string): { response: Promise<string> } & AbortableRequest {
         const { abortRequest, signal } = this.createAbortController();
         const response = this.restClient