Add a Double Page Viewer (#105)

* add double page reader

* implement singleRTL

* add on image load handler

* add retry display time interval

* remove comments

* add double page wrapper

* fix image getting out of bounds

* remove comments

* remove unused styles

* return imageStyle as type CSSProperties

* rename DoublePagedReader to DoublePagedPager

webUI/react/src/components/manga/reader/DoublePage.tsx

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+import { makeStyles } from '@material-ui/core/styles';
+import React from 'react';
+
+const useStyles = (settings: IReaderSettings) => makeStyles({
+    image: {
+        display: 'block',
+        marginBottom: 0,
+        width: 'auto',
+        minHeight: '99vh',
+        height: 'auto',
+        maxHeight: '99vh',
+        objectFit: 'contain',
+    },
+    page: {
+        display: 'flex',
+        flexDirection: settings.readerType === 'DoubleLTR' ? 'row' : 'row-reverse',
+        justifyContent: 'center',
+        margin: '0 auto',
+        width: 'auto',
+        height: 'auto',
+        overflowX: 'scroll',
+    },
+});
+
+interface IProps {
+    index: number
+    image1src: string
+    image2src: string
+    settings: IReaderSettings
+}
+
+const DoublePage = React.forwardRef((props: IProps, ref: any) => {
+    const {
+        image1src, image2src, index, settings,
+    } = props;
+
+    const classes = useStyles(settings)();
+
+    return (
+        <div ref={ref} className={classes.page}>
+            <img
+                className={classes.image}
+                src={image1src}
+                alt={`Page #${index}`}
+            />
+            <img
+                className={classes.image}
+                src={image2src}
+                alt={`Page #${index + 1}`}
+            />
+        </div>
+    );
+});
+
+export default DoublePage;

webUI/react/src/components/manga/reader/Page.tsx

@@ -7,8 +7,31 @@
 
 import CircularProgress from '@material-ui/core/CircularProgress';
 import { makeStyles } from '@material-ui/core/styles';
+import { CSSProperties } from '@material-ui/core/styles/withStyles';
 import React, { useEffect, useRef, useState } from 'react';
 
+function imageStyle(settings: IReaderSettings): CSSProperties {
+    if (settings.readerType === 'DoubleLTR' || settings.readerType === 'DoubleRTL') {
+        return {
+            display: 'block',
+            marginBottom: 0,
+            width: 'auto',
+            minHeight: '99vh',
+            height: 'auto',
+            maxHeight: '99vh',
+            objectFit: 'contain',
+        };
+    }
+
+    return {
+        display: 'block',
+        marginBottom: settings.readerType === 'ContinuesVertical' ? '15px' : 0,
+        minWidth: '50vw',
+        width: '100%',
+        maxWidth: '100%',
+    };
+}
+
 const useStyles = (settings: IReaderSettings) => makeStyles({
     loading: {
         margin: '100px auto',
@@ -22,25 +45,20 @@ const useStyles = (settings: IReaderSettings) => makeStyles({
         backgroundColor: '#525252',
         marginBottom: 10,
     },
-    image: {
+    image: imageStyle(settings),
-        display: 'block',
-        marginBottom: settings.readerType === 'ContinuesVertical' ? '15px' : 0,
-        minWidth: '50vw',
-        width: '100%',
-        maxWidth: '100%',
-    },
 });
 
 interface IProps {
     src: string
     index: number
+    onImageLoad: () => void
     setCurPage: React.Dispatch<React.SetStateAction<number>>
     settings: IReaderSettings
 }
 
 function LazyImage(props: IProps) {
     const {
-        src, index, setCurPage, settings,
+        src, index, onImageLoad, setCurPage, settings,
     } = props;
 
     const classes = useStyles(settings)();
@@ -70,7 +88,14 @@ function LazyImage(props: IProps) {
         const img = new Image();
         img.src = src;
 
-        img.onload = () => setImagsrc(src);
+        img.onload = () => {
+            setImagsrc(src);
+            onImageLoad();
+        };
+
+        return () => {
+            img.onload = null;
+        };
     }, [src]);
 
     if (imageSrc.length === 0) {
@@ -93,7 +118,7 @@ function LazyImage(props: IProps) {
 
 const Page = React.forwardRef((props: IProps, ref: any) => {
     const {
-        src, index, setCurPage, settings,
+        src, index, onImageLoad, setCurPage, settings,
     } = props;
 
     return (
@@ -101,6 +126,7 @@ const Page = React.forwardRef((props: IProps, ref: any) => {
             <LazyImage
                 src={src}
                 index={index}
+                onImageLoad={onImageLoad}
                 setCurPage={setCurPage}
                 settings={settings}
             />

webUI/react/src/components/manga/reader/pager/DoublePagedPager.tsx

@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+import { makeStyles } from '@material-ui/core/styles';
+import React, { useEffect, useRef } from 'react';
+import ReactDOM from 'react-dom';
+import Page from '../Page';
+import DoublePage from '../DoublePage';
+
+const useStyles = (settings: IReaderSettings) => makeStyles({
+    reader: {
+        display: 'flex',
+        flexDirection: (settings.readerType === 'DoubleLTR') ? 'row' : 'row-reverse',
+        justifyContent: 'center',
+        margin: '0 auto',
+        width: 'auto',
+        height: 'auto',
+        overflowX: 'scroll',
+    },
+});
+
+export default function DoublePagedPager(props: IReaderProps) {
+    const {
+        pages, settings, setCurPage, curPage, nextChapter, prevChapter,
+    } = props;
+
+    const classes = useStyles(settings)();
+
+    const selfRef = useRef<HTMLDivElement>(null);
+    const pagesRef = useRef<HTMLDivElement[]>([]);
+
+    const pagesDisplayed = useRef<number>(0);
+    const pageLoaded = useRef<boolean[]>(Array(pages.length).fill(false));
+
+    function pagesToGoBack() {
+        for (let i = 1; i <= 2; i++) {
+            if (curPage - i > 0 && pagesRef.current[curPage - i]) {
+                if (pagesRef.current[curPage - i].children[0] instanceof HTMLImageElement) {
+                    const imgElem = pagesRef.current[curPage - i].children[0] as HTMLImageElement;
+                    const aspectRatio = imgElem.height / imgElem.width;
+                    if (aspectRatio < 1) {
+                        return 1;
+                    }
+                }
+            }
+        }
+        return 2;
+    }
+
+    function nextPage() {
+        if (curPage < pages.length - 1) {
+            const nextCurPage = curPage + pagesDisplayed.current;
+            setCurPage((nextCurPage >= pages.length) ? pages.length - 1 : nextCurPage);
+        } else if (settings.loadNextonEnding) {
+            nextChapter();
+        }
+    }
+
+    function prevPage() {
+        if (curPage > 0) {
+            const nextCurPage = curPage - pagesToGoBack();
+            setCurPage((nextCurPage < 0) ? 0 : nextCurPage);
+        } else {
+            prevChapter();
+        }
+    }
+
+    function goLeft() {
+        if (settings.readerType === 'DoubleLTR') {
+            prevPage();
+        } else {
+            nextPage();
+        }
+    }
+
+    function goRight() {
+        if (settings.readerType === 'DoubleLTR') {
+            nextPage();
+        } else {
+            prevPage();
+        }
+    }
+
+    function setPagesToDisplay() {
+        pagesDisplayed.current = 0;
+        if (curPage < pages.length && pagesRef.current[curPage]) {
+            if (pagesRef.current[curPage].children[0] instanceof HTMLImageElement) {
+                pagesDisplayed.current = 1;
+                const imgElem = pagesRef.current[curPage].children[0] as HTMLImageElement;
+                const aspectRatio = imgElem.height / imgElem.width;
+                if (aspectRatio < 1) {
+                    return;
+                }
+            }
+        }
+        if (curPage + 1 < pages.length && pagesRef.current[curPage + 1]) {
+            if (pagesRef.current[curPage + 1].children[0] instanceof HTMLImageElement) {
+                const imgElem = pagesRef.current[curPage + 1].children[0] as HTMLImageElement;
+                const aspectRatio = imgElem.height / imgElem.width;
+                if (aspectRatio < 1) {
+                    return;
+                }
+                pagesDisplayed.current = 2;
+            }
+        }
+    }
+
+    function showPages() {
+        if (pagesDisplayed.current === 2) {
+            ReactDOM.render(
+                <DoublePage
+                    key={curPage}
+                    index={curPage}
+                    image1src={pages[curPage].src}
+                    image2src={pages[curPage + 1].src}
+                    settings={settings}
+                />,
+                document.getElementById('display'),
+            );
+        } else if (pagesDisplayed.current === 1) {
+            ReactDOM.render(
+                <Page
+                    key={curPage}
+                    index={curPage}
+                    src={pages[curPage].src}
+                    onImageLoad={() => {}}
+                    setCurPage={setCurPage}
+                    settings={settings}
+                />,
+                document.getElementById('display'),
+            );
+        } else {
+            ReactDOM.render(
+                <div />,
+                document.getElementById('display'),
+            );
+        }
+    }
+
+    function keyboardControl(e:KeyboardEvent) {
+        switch (e.code) {
+            case 'Space':
+                e.preventDefault();
+                nextPage();
+                break;
+            case 'ArrowRight':
+                goRight();
+                break;
+            case 'ArrowLeft':
+                goLeft();
+                break;
+            default:
+                break;
+        }
+    }
+
+    function clickControl(e:MouseEvent) {
+        if (e.clientX > window.innerWidth / 2) {
+            goRight();
+        } else {
+            goLeft();
+        }
+    }
+
+    function handleImageLoad(index: number) {
+        return () => {
+            pageLoaded.current[index] = true;
+        };
+    }
+
+    useEffect(() => {
+        pagesRef.current.forEach((e) => {
+            const pageRef = e;
+            pageRef.style.display = 'none';
+        });
+    }, []);
+
+    useEffect(() => {
+        const retryDisplay = setInterval(() => {
+            const isLastPage = (curPage === pages.length - 1);
+            if ((!isLastPage && pageLoaded.current[curPage] && pageLoaded.current[curPage + 1])
+                || pageLoaded.current[curPage]) {
+                setPagesToDisplay();
+                showPages();
+                clearInterval(retryDisplay);
+            }
+        }, 50);
+
+        document.addEventListener('keydown', keyboardControl);
+        selfRef.current?.addEventListener('click', clickControl);
+
+        return () => {
+            clearInterval(retryDisplay);
+            document.removeEventListener('keydown', keyboardControl);
+            selfRef.current?.removeEventListener('click', clickControl);
+        };
+    }, [selfRef, curPage, settings.readerType]);
+
+    return (
+        <div ref={selfRef}>
+            <div id="preload" className={classes.reader}>
+                {
+                    pages.map((page) => (
+                        <Page
+                            key={page.index}
+                            index={page.index}
+                            src={page.src}
+                            onImageLoad={handleImageLoad(page.index)}
+                            setCurPage={setCurPage}
+                            settings={settings}
+                            ref={(e:HTMLDivElement) => { pagesRef.current[page.index] = e; }}
+                        />
+                    ))
+                }
+            </div>
+            <div id="display" className={classes.reader} />
+        </div>
+    );
+}

webUI/react/src/components/manga/reader/pager/HorizontalPager.tsx

@@ -40,6 +40,7 @@ export default function HorizontalPager(props: IProps) {
                         key={page.index}
                         index={page.index}
                         src={page.src}
+                        onImageLoad={() => {}}
                         setCurPage={setCurPage}
                         settings={settings}
                     />

webUI/react/src/components/manga/reader/pager/PagedPager.tsx

@@ -38,7 +38,27 @@ export default function PagedReader(props: IReaderProps) {
     }
 
     function prevPage() {
-        if (curPage > 0) { setCurPage(curPage - 1); } else if (curPage === 0) { prevChapter(); }
+        if (curPage > 0) {
+            setCurPage(curPage - 1);
+        } else {
+            prevChapter();
+        }
+    }
+
+    function goLeft() {
+        if (settings.readerType === 'SingleLTR') {
+            prevPage();
+        } else if (settings.readerType === 'SingleRTL') {
+            nextPage();
+        }
+    }
+
+    function goRight() {
+        if (settings.readerType === 'SingleLTR') {
+            nextPage();
+        } else if (settings.readerType === 'SingleRTL') {
+            prevPage();
+        }
     }
 
     function keyboardControl(e:KeyboardEvent) {
@@ -48,10 +68,10 @@ export default function PagedReader(props: IReaderProps) {
                 nextPage();
                 break;
             case 'ArrowRight':
-                nextPage();
+                goRight();
                 break;
             case 'ArrowLeft':
-                prevPage();
+                goLeft();
                 break;
             default:
                 break;
@@ -60,9 +80,9 @@ export default function PagedReader(props: IReaderProps) {
 
     function clickControl(e:MouseEvent) {
         if (e.clientX > window.innerWidth / 2) {
-            nextPage();
+            goRight();
         } else {
-            prevPage();
+            goLeft();
         }
     }
 
@@ -74,13 +94,14 @@ export default function PagedReader(props: IReaderProps) {
             document.removeEventListener('keydown', keyboardControl);
             selfRef.current?.removeEventListener('click', clickControl);
         };
-    }, [selfRef, curPage]);
+    }, [selfRef, curPage, settings.readerType]);
 
     return (
         <div ref={selfRef} className={classes.reader}>
             <Page
                 key={curPage}
                 index={curPage}
+                onImageLoad={() => {}}
                 src={pages[curPage].src}
                 setCurPage={setCurPage}
                 settings={settings}

webUI/react/src/components/manga/reader/pager/VerticalPager.tsx

@@ -114,6 +114,7 @@ export default function VerticalReader(props: IReaderProps) {
                         key={page.index}
                         index={page.index}
                         src={page.src}
+                        onImageLoad={() => {}}
                         setCurPage={setCurPage}
                         settings={settings}
                         ref={(e:HTMLDivElement) => { pagesRef.current[page.index] = e; }}

webUI/react/src/components/navbar/ReaderNavBar.tsx

@@ -286,17 +286,25 @@ export default function ReaderNavBar(props: IProps) {
                                     onChange={(e) => setSettingValue('readerType', e.target.value)}
                                 >
                                     <MenuItem value="SingleLTR">
-                                        Left to right
+                                        Single Page (LTR)
 
                                     </MenuItem>
-                                    {/* <MenuItem value="SingleRTL">
+                                    <MenuItem value="SingleRTL">
-                                        Right to left(WIP)
+                                        Single Page (RTL)
 
-                                    </MenuItem> */}
+                                    </MenuItem>
                                     {/* <MenuItem value="SingleVertical">
                                         Vertical(WIP)
 
                                     </MenuItem> */}
+                                    <MenuItem value="DoubleLTR">
+                                        Double Page (LTR)
+
+                                    </MenuItem>
+                                    <MenuItem value="DoubleRTL">
+                                        Double Page (RTL)
+
+                                    </MenuItem>
                                     <MenuItem value="Webtoon">
                                         Webtoon
 

webUI/react/src/screens/manga/Reader.tsx

@@ -11,7 +11,8 @@ import React, { useContext, useEffect, useState } from 'react';
 import { useHistory, useParams } from 'react-router-dom';
 import HorizontalPager from 'components/manga/reader/pager/HorizontalPager';
 import PageNumber from 'components/manga/reader/PageNumber';
-import WebtoonPager from 'components/manga/reader/pager/PagedPager';
+import PagedPager from 'components/manga/reader/pager/PagedPager';
+import DoublePagedPager from 'components/manga/reader/pager/DoublePagedPager';
 import VerticalPager from 'components/manga/reader/pager/VerticalPager';
 import ReaderNavBar, { defaultReaderSettings } from 'components/navbar/ReaderNavBar';
 import NavbarContext from 'context/NavbarContext';
@@ -32,19 +33,18 @@ const useStyles = (settings: IReaderSettings) => makeStyles({
 const getReaderComponent = (readerType: ReaderType) => {
     switch (readerType) {
         case 'ContinuesVertical':
-            return VerticalPager;
-            break;
         case 'Webtoon':
             return VerticalPager;
             break;
         case 'SingleVertical':
-            return WebtoonPager;
-            break;
         case 'SingleRTL':
-            return WebtoonPager;
-            break;
         case 'SingleLTR':
-            return WebtoonPager;
+            return PagedPager;
+            break;
+        case 'DoubleVertical':
+        case 'DoubleRTL':
+        case 'DoubleLTR':
+            return DoublePagedPager;
             break;
         case 'ContinuesHorizontal':
             return HorizontalPager;

webUI/react/src/typings.d.ts

@@ -114,6 +114,9 @@ type ReaderType =
 'SingleVertical' |
 'SingleRTL' |
 'SingleLTR' |
+'DoubleVertical' |
+'DoubleRTL' |
+'DoubleLTR' |
 'ContinuesHorizontal';
 
 interface IReaderSettings{