1. 截取内容为div
2. 通过html2canvas截取 生成Bob | base64
3. 保存图片到本地(无法下载的生成图片,长按图片保存到本地)

• style

    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        .view {
            width: 375px;
            height: 667px;
            position: relative;
            color: #FFFFFF;
            text-align: center;
            font-size: 20px;
            background: #409EFF;
        }

        .title {
            width: 100%;
            font-size: 30px;
            position: absolute;
            top: 50px;
            left: 50%;
            transform: translateX(-50%);
        }

        .content {
            width: 100%;
            font-size: 16px;
            position: absolute;
            top: 100px;
            left: 50%;
            transform: translateX(-50%);
        }

        .result {
            width: 375px;
            height: 667px;
        }

        .result>img {
            width: 100%;
            height: 100%;
        }

        .btn {
            padding: 10px;
        }

        button {
            padding: 6px 10px;
        }
    </style>

• html

    <div class="btn">
        <button onclick="saveFile()">保存海报</button>
        <button onclick="drawImage()">生成图片</button>
    </div>
    <div id="capture" class="view">
        <div class="title">海报标题</div>
        <div class="content">海报内容</div>
    </div>
    <br>
    <hr>
    <div id="result" class="result"></div>

• js

  <script src="https://cdn.bootcdn.net/ajax/libs/html2canvas/1.4.1/html2canvas.js"></script>
    <script>
        function saveFile() {
            let dpi = window.devicePixelRatio || 2
            let options = {
                useCORS: true,
                ignoreElements: false,
                scale: dpi //设置默认值 提高图片分辨率
            };
            html2canvas(document.querySelector("#capture"), options).then(canvas => {
                // document.body.appendChild(canvas)
                canvas.toBlob(function (blob) {
                    downloadBob(blob);
                });
            });
        }
        function drawImage() {
            let dpi = window.devicePixelRatio || 2
            let options = {
                useCORS: true,
                ignoreElements: false,
                scale: dpi //设置默认值 提高图片分辨率
            };
            html2canvas(document.querySelector("#capture"), options).then(canvas => {
                let url = canvas.toDataURL('image/png') //base64
                document.querySelector('#result').innerHTML = `<img src="${url}"  alt="海报" />`
            });
        }

        // 下载不了的 生成图片长按保存 
        function downloadBob(blob) {
            var a = document.createElement('a');
            var url = window.URL.createObjectURL(blob);
            var filename = '海报.png';
            a.href = url;
            a.download = filename;
            a.click();
            window.URL.revokeObjectURL(url);
        }
    </script>