liberama/client/components/Reader/TextPage/TextPage.vue

<template>
    <div ref="main" class="main">
        <div v-show="activeCanvas" class="layout">
            <div v-html="page1"></div>
        </div>
        <div v-show="!activeCanvas" class="layout">
            <div v-html="page2"></div>
        </div>
        <div v-show="showStatusBar" ref="statusBar" class="layout">
            <div v-html="statusBar"></div>
        </div>
        <div ref="layoutEvents" class="layout events" @mousedown.prevent.stop="onMouseDown" @mouseup.prevent.stop="onMouseUp"
            @wheel.prevent.stop="onMouseWheel"
            @touchstart.stop="onTouchStart" @touchend.stop="onTouchEnd" @touchcancel.prevent.stop="onTouchCancel"
            oncontextmenu="return false;">
            <div v-show="showStatusBar" v-html="statusBarClickable" @mousedown.prevent.stop @touchstart.stop
                @click.prevent.stop="onStatusBarClick"></div>
        </div>
        <canvas ref="offscreenCanvas" style="display: none"></canvas>
    </div>
</template>

<script>
//-----------------------------------------------------------------------------
import Vue from 'vue';
import Component from 'vue-class-component';
import _ from 'lodash';
import {sleep} from '../../../share/utils';

import bookManager from '../share/bookManager';
import DrawHelper from './DrawHelper';

export default @Component({
    watch: {
        bookPos: function(newValue) {
            this.debouncedEmitPosChange(newValue);
            this.draw();
        },
    },
})
class TextPage extends Vue {
    activeCanvas = false;
    showStatusBar = false;
    page1 = null;
    page2 = null;
    statusBar = null;
    statusBarClickable = null;

    lastBook = null;
    bookPos = 0;

    fontStyle = null;
    fontSize = null;
    fontName = null;

    meta = null;

    created() {
        this.drawHelper = new DrawHelper();

        this.commit = this.$store.commit;
        this.dispatch = this.$store.dispatch;
        this.config = this.$store.state.config;
        this.reader = this.$store.state.reader;

        this.debouncedEmitPosChange = _.debounce((newValue) => {
            this.$emit('book-pos-changed', {bookPos: newValue});
        }, 1000);

        this.debouncedStartClickRepeat = _.debounce((x, y) => {
            this.startClickRepeat(x, y);
        }, 800);

        this.debouncedPrepareNextPage = _.debounce(() => {
            this.prepareNextPage();
        }, 100);

        this.debouncedDrawStatusBar = _.throttle(() => {
            this.drawStatusBar();
        }, 60);        

        this.$root.$on('resize', () => {this.$nextTick(this.onResize)});
        this.mobile = /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent);
    }

    mounted() {
        this.context = this.$refs.offscreenCanvas.getContext('2d');
    }

    hex2rgba(hex, alpha = 1) {
        const [r, g, b] = hex.match(/\w\w/g).map(x => parseInt(x, 16));
        return `rgba(${r},${g},${b},${alpha})`;
    }

    async calcDrawProps() {
        this.realWidth = this.$refs.main.clientWidth;
        this.realHeight = this.$refs.main.clientHeight;

        this.$refs.layoutEvents.style.width = this.realWidth + 'px';
        this.$refs.layoutEvents.style.height = this.realHeight + 'px';

        this.activeCanvas = false;

        this.w = this.realWidth - 2*this.indent;
        this.h = this.realHeight - (this.showStatusBar ? this.statusBarHeight : 0);
        this.lineHeight = this.fontSize + this.lineInterval;
        this.pageLineCount = Math.floor(this.h/this.lineHeight);

        if (this.parsed) {
            this.parsed.p = this.p;
            this.parsed.w = this.w;// px, ширина текста
            this.parsed.font = this.font;
            this.parsed.wordWrap = this.wordWrap;
            this.parsed.measureText = this.measureText;
        }

        this.statusBarColor = this.hex2rgba(this.textColor, this.statusBarColorAlpha);
        this.currentTransition = '';
        this.pageChangeDirectionDown = true;
        this.fontShift = (this.fontShifts[this.fontName] ? this.fontShifts[this.fontName] : 0)/100;

        //drawHelper
        this.drawHelper.realWidth = this.realWidth;
        this.drawHelper.realHeight = this.realHeight;

        this.drawHelper.backgroundColor = this.backgroundColor;
        this.drawHelper.statusBarColor = this.statusBarColor;
        this.drawHelper.fontName = this.fontName;
        this.drawHelper.fontShift = this.fontShift;
        this.drawHelper.measureText = this.measureText;
        this.drawHelper.measureTextFont = this.measureTextFont;

        this.$refs.statusBar.style.left = '0px';
        this.$refs.statusBar.style.top = (this.statusBarTop ? 1 : this.realHeight - this.statusBarHeight) + 'px';

        this.statusBarClickable = this.drawHelper.statusBarClickable(this.statusBarTop, this.statusBarHeight);
    }

    measureText(text, style) {// eslint-disable-line no-unused-vars
        this.context.font = this.fontByStyle(style);
        return this.context.measureText(text).width;
    }

    measureTextFont(text, font) {// eslint-disable-line no-unused-vars
        this.context.font = font;
        return this.context.measureText(text).width;
    }

    async loadFonts() {
        let loaded = await Promise.all(this.fontList.map(font => document.fonts.check(font)));
        if (loaded.some(r => !r)) {
            loaded = await Promise.all(this.fontList.map(font => document.fonts.load(font)));
            if (loaded.some(r => !r.length))
                throw new Error('some font not loaded');
        }
    }

    showBook() {
        this.$refs.main.focus();
        this.book = null;
        this.meta = null;
        this.fb2 = null;
        this.parsed = null;

        this.linesUp = null;
        this.linesDown = null;

        //preloaded fonts
        this.fontShifts = {//%
            ReaderDefault: 0,
            Arial: 5,
            ComicSansMS: -12,
            OpenSans: 0,
            Roboto: 0,
            ArialNarrow: 0,
            Georgia: 0,
            Tahoma: 0,
            Helvetica: 0,
            CenturySchoolbook: 0,
        }
        this.fontList = [];
        for (let fontName in this.fontShifts)
            this.fontList.push(`12px ${fontName}`);

        //default draw props
        this.textColor = '#000000';
        this.backgroundColor = '#478355';
        this.fontStyle = '';// 'bold','italic'
        this.fontSize = 35;// px
        this.fontName = 'ComicSansMS';
        this.lineInterval = 7;// px, межстрочный интервал
        this.textAlignJustify = true;// выравнивание по ширине
        this.p = 50;// px, отступ параграфа
        this.indent = 15;// px, отступ всего текста слева и справа
        this.wordWrap = true;
        this.keepLastToFirst = true;// перенос последней строки в первую при листании

        this.showStatusBar = true;
        this.statusBarTop = false;// top, bottom
        this.statusBarHeight = 20;// px
        this.statusBarColorAlpha = 0.4;

        this.pageChangeTransition = '';// '' - нет, downShift, rightShift, thaw - протаивание, blink - мерцание
        this.pageChangeTransitionSpeed = 50; //0-100%

        this.calcDrawProps();
        this.draw(true);// пока не загрузили, очистим канвас

        if (this.lastBook) {
            (async() => {
                const isParsed = await bookManager.hasBookParsed(this.lastBook);
                if (!isParsed) {
                    return;
                }
                this.book = await bookManager.getBook(this.lastBook);
                this.meta = bookManager.metaOnly(this.book);
                this.fb2 = this.meta.fb2;

                const authorName = _.compact([
                    this.fb2.lastName,
                    this.fb2.firstName,
                    this.fb2.middleName
                ]).join(' ');
                this.title = _.compact([
                    authorName,
                    this.fb2.bookTitle
                ]).join(' - ');

                this.$root.$emit('set-app-title', this.title);

                const parsed = this.book.parsed;
                this.parsed = parsed;
                this.calcDrawProps();

                await this.loadFonts();

                this.draw();
                this.refreshTime();
            })();
        }
    }

    onResize() {
        this.calcDrawProps();
        this.draw(true);
    }

    get font() {
        return `${this.fontStyle} ${this.fontSize}px ${this.fontName}`;
    }

    fontByStyle(style) {
        return `${style.italic ? 'italic' : ''} ${style.bold ? 'bold' : ''} ${this.fontSize}px ${this.fontName}`;
    }

    draw(immediate) {
        if (this.book && this.bookPos > 0 && this.bookPos >= this.parsed.textLength) {
            this.doEnd();
            return;
        }

        this.activeCanvas = !this.activeCanvas;

        if (immediate) {            
            if (this.activeCanvas)
                this.page1 = this.drawPage(this.bookPos);
            else
                this.page2 = this.drawPage(this.bookPos);
        } else {
            if (this.pageChangeDirectionDown && this.pagePrepared && this.bookPos == this.bookPosPrepared) {
                this.linesDown = this.linesDownNext;
                this.linesUp = this.linesUpNext;
                this.pagePrepared = false;
                this.debouncedPrepareNextPage();
            } else {
                if (this.activeCanvas)
                    this.page1 = this.drawPage(this.bookPos);
                else
                    this.page2 = this.drawPage(this.bookPos);
                this.pagePrepared = false;
                this.debouncedPrepareNextPage();
            }

            if (this.currentTransition) {
                //this.currentTransition
                //this.pageChangeTransitionSpeed
                //this.pageChangeDirectionDown  
                
                //curr to next transition
                //пока заглушка
            }

            this.currentTransition = '';
            this.pageChangeDirectionDown = false;//true только если PgDown
        }

        this.debouncedDrawStatusBar();
    }

    drawPage(bookPos, nextChangeLines) {
        if (!this.lastBook)
            return;

        let out = `<div class="layout" style="width: ${this.realWidth}px; height: ${this.realHeight}px;` + 
            ` color: ${this.textColor}; background-color: ${this.backgroundColor}">`;

        if (!this.book || !this.parsed.textLength) {
            out += '</div>';
            return out;
        }

        const spaceWidth = this.measureText(' ', {});

        const lines = this.parsed.getLines(bookPos, 2*this.pageLineCount);
        if (!nextChangeLines) {
            this.linesDown = lines;
            this.linesUp = this.parsed.getLines(bookPos, -2*this.pageLineCount);
        } else {
            this.linesDownNext = lines;
            this.linesUpNext = this.parsed.getLines(bookPos, -2*this.pageLineCount);
        }

        let y = -this.lineInterval/2 + (this.h - this.pageLineCount*this.lineHeight)/2 + this.fontSize*this.fontShift;
        if (this.showStatusBar)
            y += this.statusBarHeight*(this.statusBarTop ? 1 : 0);

        let len = lines.length;
        len = (len > this.pageLineCount ? len = this.pageLineCount : len);
        for (let i = 0; i < len; i++) {
            const line = lines[i];
            /* line:
            {
                begin: Number,
                end: Number,
                first: Boolean,
                last: Boolean,
                parts: array of {
                    style: {bold: Boolean, italic: Boolean, center: Boolean}
                    text: String,
                }
            }*/

            let indent = this.indent + (line.first ? this.p : 0);

            let lineText = '';
            let center = false;
            let centerStyle = {};
            for (const part of line.parts) {
                lineText += part.text;
                center = center || part.style.center;
                if (part.style.center)
                    centerStyle = part.style.center;
            }

            let filled = false;
            // если выравнивание по ширине включено
            if (this.textAlignJustify && !line.last && !center) {
                const words = lineText.split(' ');

                if (words.length > 1) {
                    const spaceCount = words.length - 1;

                    const space = (this.w - line.width + spaceWidth*spaceCount)/spaceCount;

                    let x = indent;
                    for (const part of line.parts) {
                        const font = this.fontByStyle(part.style);
                        let partWords = part.text.split(' ');

                        for (let i = 0; i < partWords.length; i++) {
                            let word = partWords[i];
                            out += this.drawHelper.fillText(word, x, y, font);
                            x += this.measureText(word, part.style) + (i < partWords.length - 1 ? space : 0);
                        }
                    }
                    filled = true;
                }
            }

            // просто выводим текст
            if (!filled) {
                let x = indent;
                x = (center ? this.indent + (this.w - this.measureText(lineText, centerStyle))/2 : x);
                for (const part of line.parts) {
                    let text = part.text;
                    const font = this.fontByStyle(part.style);
                    out += this.drawHelper.fillText(text, x, y, font);
                    x += this.measureText(text, part.style);
                }
            }
            y += this.lineHeight;
        }

        out += '</div>';
        return out;
    }

    drawStatusBar() {
        if (this.showStatusBar && this.linesDown) {
            const lines = this.linesDown;
            let i = this.pageLineCount;
            if (this.keepLastToFirst)
                i--;
            i = (i > lines.length - 1 ? lines.length - 1 : i);

            this.statusBar = this.drawHelper.drawStatusBar(this.statusBarTop, this.statusBarHeight, 
                lines[i].end, this.parsed.textLength, this.title);
        }
    }

    async refreshTime() {
        if (!this.timeRefreshing) {
            this.timeRefreshing = true;
            await sleep(60*1000);

            if (this.book && this.parsed.textLength) {
                this.debouncedDrawStatusBar();
            }
            this.timeRefreshing = false;
            this.refreshTime();
        }
    }

    prepareNextPage() {
        // подготовка следующей страницы заранее        
        if (!this.book || !this.parsed.textLength)
            return;
        
        if (!this.preparing) {
            this.preparing = true;

            (async() => {
                await sleep(100);
                if (this.cancelPrepare) {
                    this.preparing = false;
                    return;
                }

                let i = this.pageLineCount;
                if (this.keepLastToFirst)
                    i--;
                if (i >= 0 && this.linesDown.length > i) {
                    this.bookPosPrepared = this.linesDown[i].begin;

                    if (this.activeCanvas)
                        this.page2 = this.drawPage(this.bookPosPrepared, true);//наоборот
                    else
                        this.page1 = this.drawPage(this.bookPosPrepared, true);
  
                    this.pagePrepared = true;
                }

                this.preparing = false;
            })();
        }
    }

    doDown() {
        if (this.linesDown && this.linesDown.length > this.pageLineCount) {
            this.bookPos = this.linesDown[1].begin;
        }
    }

    doUp() {
        if (this.linesUp && this.linesUp.length > 1) {
            this.bookPos = this.linesUp[1].begin;
        }
    }

    doPageDown() {
        if (this.linesDown) {
            let i = this.pageLineCount;
            if (this.keepLastToFirst)
                i--;
            if (i >= 0 && this.linesDown.length >= 2*i) {
                this.currentTransition = this.pageChangeTransition;
                this.pageChangeDirectionDown = true;
                this.bookPos = this.linesDown[i].begin;
            } else 
                this.doEnd();
        }
    }

    doPageUp() {
        if (this.linesUp) {
            let i = this.pageLineCount;
            if (this.keepLastToFirst)
                i--;
            i = (i > this.linesUp.length - 1 ? this.linesUp.length - 1 : i);
            if (i >= 0 && this.linesUp.length > i) {
                this.currentTransition = this.pageChangeTransition;
                this.pageChangeDirectionDown = false;
                this.bookPos = this.linesUp[i].begin;
            }
        }
    }

    doHome() {
        this.bookPos = 0;
    }

    doEnd() {
        if (this.parsed.para.length) {
            let i = this.parsed.para.length - 1;
            let lastPos = this.parsed.para[i].offset + this.parsed.para[i].length - 1;
            const lines = this.parsed.getLines(lastPos, -this.pageLineCount);
            i = this.pageLineCount - 1;
            i = (i > lines.length - 1 ? lines.length - 1 : i);
            this.bookPos = lines[i].begin;
        }
    }

    doToolBarToggle() {
        this.$emit('tool-bar-toggle');
    }

    keyHook(event) {
        if (event.type == 'keydown') {
            switch (event.code) {
                case 'ArrowDown':
                    this.doDown();
                    break;
                case 'ArrowUp':
                    this.doUp();
                    break;
                case 'PageDown':
                case 'ArrowRight':
                case 'Enter':
                case 'Space':
                    this.doPageDown();
                    break;
                case 'PageUp':
                case 'ArrowLeft':
                case 'Backspace':
                    this.doPageUp();
                    break;
                case 'Home':
                    this.doHome();
                    break;
                case 'End':
                    this.doEnd();
                    break;
            }
        }
    }

    async startClickRepeat(pointX, pointY) {
        this.repX = pointX;
        this.repY = pointY;

        if (!this.repInit && this.repDoing) {
            this.repInit = true;
            let delay = 400;
            while (this.repDoing) {
                this.handleClick(pointX, pointY);
                await sleep(delay);
                if (delay > 15)
                    delay *= 0.8;
            }
            this.repInit = false;
        }
    }

    endClickRepeat() {
        this.repDoing = false;
    }

    onTouchStart(event) {
        if (!this.mobile)
            return;
        this.endClickRepeat();
        if (event.touches.length == 1) {
            const touch = event.touches[0];
            const rect = event.target.getBoundingClientRect();
            const x = touch.pageX - rect.left;
            const y = touch.pageY - rect.top;
            if (this.handleClick(x, y)) {
                this.repDoing = true;
                this.debouncedStartClickRepeat(x, y);
            }
        }
    }

    onTouchEnd() {
        if (!this.mobile)
            return;
        this.endClickRepeat();
    }

    onTouchCancel() {
        if (!this.mobile)
            return;
        this.endClickRepeat();
    }

    onMouseDown(event) {
        if (this.mobile)
            return;
        this.endClickRepeat();
        if (event.button == 0) {
            if (this.handleClick(event.offsetX, event.offsetY)) {
                this.repDoing = true;
                this.debouncedStartClickRepeat(event.offsetX, event.offsetY);
            }
        } else if (event.button == 2) {
            this.doToolBarToggle();
        }
    }

    onMouseUp() {
        if (this.mobile)
            return;
        this.endClickRepeat();
    }

    onMouseWheel(event) {
        if (this.mobile)
            return;
        if (event.deltaY > 0) {
            this.doDown();
        } else if (event.deltaY < 0) {
            this.doUp();
        }
    }

    onStatusBarClick() {
        window.open(this.meta.url, '_blank');
    }

    handleClick(pointX, pointY) {
        const mouseLegend = {
            40: {30: 'PgUp', 100: 'PgDown'},
            60: {40: 'Up', 60: 'Menu', 100: 'Down'},
            100: {30: 'PgUp', 100: 'PgDown'}
        };

        const w = pointX/this.realWidth*100;
        const h = pointY/this.realHeight*100;

        let action = '';
        loops: {
            for (const x in mouseLegend) {
                for (const y in mouseLegend[x]) {
                    if (w < x && h < y) {
                        action = mouseLegend[x][y];
                        break loops;
                    }
                }
            }
        }

        switch (action) {
            case 'Down' ://Down
                this.doDown();
                break;
            case 'Up' ://Up
                this.doUp();
                break;
            case 'PgDown' ://PgDown
                this.doPageDown();
                break;
            case 'PgUp' ://PgUp
                this.doPageUp();
                break;
            case 'Menu' :
                this.doToolBarToggle();
                break;
            default :
                // Nothing
        }

        return (action && action != 'Menu');
   }

}
//-----------------------------------------------------------------------------
</script>
<style scoped>
.main {
    flex: 1;
    margin: 0;
    padding: 0;
    overflow: hidden;
    position: relative;
}

.layout {
    margin: 0;
    padding: 0;
    position: absolute;
    z-index: 10;
}

.events {
    z-index: 20;
    background-color: rgba(0,0,0,0);
}
</style>