src/components/BChart.vue

<template>
    <div>
        <div slot="header" class="clearfix text-base" v-if="!isExportingVideo">
            {{$t('preview')}}
            <a href="javascript:;" @click="run()">
                <i class="el-icon-refresh"></i>
            </a>
        </div>
        <div slot="header" class="clearfix text-base" v-if="isExportingVideo">
            <i class="el-icon-loading"></i>
            {{$t('exporting')}}
            <el-button @click="cancelDownload()" >
                {{$t('cancel')}}
            </el-button>
        </div>
        <div
            id="bar-race-preview"
            ref="chart"
            class="absolute bottom-4 top-16 left-5 right-5 border"
            :class="isExportingVideo ? 'top-28' : ''"
        >
        </div>
    </div>
</template>

<script lang="ts">
import {defineComponent} from 'vue';
import * as timeline from '../helper/timeline';
import * as echarts from 'echarts';
import WebMWriter from 'webm-writer';

const headerLength = 2;
let chart: echarts.ECharts;
let recorder;

function wait(time: number) {
    return new Promise((resolve) => {
        setTimeout(resolve, time);
    });
}

export default defineComponent({
    name: 'BChart',
    props: {
        title: String,
        chartData: Array,
        maxDataCnt: Number,
        animationDuration: Number,
        sortDuration: Number
    },
    data() {
        return {
            timeoutHandlers: [],
            isExportingVideo: false
        };
    },
    watch: {
        chartData() {
            this.run();
        }
    },
    mounted() {
    },
    methods: {
        async run() {
            this.doResetChart();
            await this.doRun();
        },

        async captureVideo(width: number, height: number, fps: number) {
            try {
                this.isExportingVideo = true;
                this.doResetChart(width, height, 1);
                const container = chart.getDom();
                const canvas = container.children[0].children[0] as HTMLCanvasElement;
                if (container.clientHeight) {
                    if (container.clientWidth / container.clientHeight > width / height) {
                        canvas.style.height = container.clientHeight + 'px';
                        canvas.style.width = container.clientHeight / height * width + 'px';
                    }
                    else {
                        canvas.style.width = container.clientWidth + 'px';
                        canvas.style.height = container.clientWidth / width * height + 'px';
                    }
                }

                recorder = new WebMWriter({
                    frameRate: fps || 30,
                    transparent: true
                });

                timeline.setFixedFrameRate(fps);
                timeline.startMock(elapsed => {
                    recorder.addFrame(canvas);
                });

                const title = this.title || this.$t('toolName') || 'bar-racing';

                await this.doRun();
                // Canceld
                if (!this.isExportingVideo) {
                    return;
                }
                const webMBlob = await recorder.complete()
                // Canceld
                if (!this.isExportingVideo) {
                    return;
                }

                const url = URL.createObjectURL(webMBlob);
                const link = document.createElement('a');
                link.download = title;
                link.href = url;
                const event = new MouseEvent('click');
                link.dispatchEvent(event);
                setTimeout(() => {
                    URL.revokeObjectURL(url);
                }, 1);

                timeline.stopMock();
                this.isExportingVideo = false;
                return true;
            }
            catch (e) {
                // Reset
                timeline.stopMock();
                this.isExportingVideo = false;

                console.error(e);
                await wait(50);
                this.run();
                return;
            }
        },

        cancelDownload() {
            if (recorder) {
                recorder.complete();
                recorder = null;
            }

            timeline.stopMock();
            this.isExportingVideo = false;
            setTimeout(() => {
                this.run();
            });
            this.$emit('downloadCancelled');
        },

        doResetChart(width?: number, height?: number, dpr?: number) {
            if (chart) {
                chart.dispose();
                chart = null;
            }

            chart = echarts.init(this.$refs.chart as HTMLElement, null, {
                width: width || undefined,
                height: height || undefined,
                devicePixelRatio: dpr
            });

            if (!this.chartData || this.chartData.length < headerLength) {
                return;
            }

            const animationDuration = this.animationDuration;
            try {
                const option = {
                    backgroundColor: '#fff',
                    xAxis: {
                        type: 'value',
                        max: 'dataMax'
                    },
                    yAxis: {
                        type: 'category',
                        data: (this.chartData[0] as string[]).slice(1),
                        inverse: true,
                        animationDuration: this.sortDuration || 300,
                        animationDurationUpdate: this.sortDuration || 300,
                        max: this.maxDataCnt ? this.maxDataCnt - 1 : null
                    },
                    color: this.chartData[1].length > 1 ? this.chartData[1].slice(1) : null,
                    series: [{
                        id: 'bar',
                        type: 'bar',
                        data: (this.chartData[headerLength] as string[]).slice(1).map(str => parseInt(str, 10)),
                        seriesLayoutBy: 'row',
                        realtimeSort: true,
                        silent: true,
                        label: {
                            show: true,
                            position: 'right'
                        },
                        colorBy: 'item'
                    }],
                    grid: {
                        right: 60,
                        bottom: 30,
                        left: 110
                    },
                    title: [{
                        text: (this.chartData as any)[headerLength][0],
                        right: 20,
                        bottom: 15,
                        textStyle: {
                            color: '#ccc',
                            opacity: 0.3,
                            fontSize: 70
                        }
                    }, {
                        text: this.title,
                        left: 10,
                        top: 10
                    }],
                    animationDuration: 0,
                    animationDurationUpdate: animationDuration,
                    animationEasing: 'linear',
                    animationEasingUpdate: 'linear'
                };
                chart.setOption(option as echarts.EChartsOption, true);
            }
            catch (e) {}
        },

        async doRun(onProgress?: (curr: number, total: number) => void) {
            if (!this.chartData || this.chartData.length < headerLength) {
                return;
            }
            const dataCnt = this.chartData.length - headerLength - 1;
            const that = this;

            function step(row) {
                chart.setOption({
                    series: [{
                        type: 'bar',
                        id: 'bar',
                        data: row.slice(1).map(str => parseInt(str, 10)),
                        label: {
                            valueAnimation: true
                        },
                        silent: that.isExportingVideo
                    }],
                    title: [{
                        text: row[0]
                    }]
                });

                return new Promise((resolve) => {
                    setTimeout(() => {
                        resolve(undefined);
                    }, that.animationDuration)
                })
            }

            for (let i = 0; i < dataCnt; ++i) {
                // Cancled.
                if (!this.isExportingVideo) {
                    return;
                }
                const row = that.chartData[headerLength + i + 1] as string[];
                await step(row);
            }
        }
    }
})
</script>

<style>
.hidden {
    visibility: hidden;
}

#chart-hint {
    position: absolute;
    top: 55px;
    left: 20px;
    color: #999;
}
</style>