html2canvas method code for saving high-definition images in divs-HTML Tutorial-php.cn

html2canvas method code for saving high-definition images in divs

小云云

Release： 2018-03-06 09:30:33

Original

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This article mainly introduces relevant information to you about the method of saving high-definition pictures in p using html2canvas. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Hope it helps everyone.

http://www.bootcdn.cn/ (you can search for html2canvans)

1. Select the html2canvas version (this version can be enlarged to ensure clear images)

Generated by default The canvas image is very blurry on retina devices. Processing it into a 2x image can solve this problem:

var w = $("#code").width();
var h = $("#code").height();

//要将 canvas 的宽高设置成容器宽高的 2 倍
var canvas = document.createElement("canvas");
canvas.width = w * 2;
canvas.height = h * 2;
canvas.style.width = w + "px";
canvas.style.height = h + "px";
var context = canvas.getContext("2d");
//然后将画布缩放，将图像放大两倍画到画布上
context.scale(2,2);

html2canvas(document.querySelector("#code"), {
    canvas: canvas,
    onrendered: function(canvas) {
        ...
    }
});

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Download method:

.on(&#39;click&#39;,&#39;.download&#39;,function(){
                $(&#39;#mycanvas&#39;).remove();
                var _height=$(&#39;.skinReport&#39;).height();
                //滚到顶部
                $(&#39;html, body&#39;).animate({scrollTop:0});

                if(confirm(&#39;是否下载肌肤检测报告？&#39;))
                {

                    setTimeout(function(){
                        var canvas = document.createElement("canvas"),
                            w=$(&#39;#skinReport&#39;).width(),
                            h=$(&#39;#skinReport&#39;).height();
                        canvas.width = w * 2;
                        canvas.height = h * 2;
                        canvas.style.width = w + "px";
                        canvas.style.height = h + "px";
                        var context = canvas.getContext("2d");
//然后将画布缩放，将图像放大两倍画到画布上
                        context.scale(2,2);
                        html2canvas(document.getElementById(&#39;skinReport&#39;), {
                            allowTaint: false,
                            taintTest: true,
                            canvas: canvas,
                            onrendered: function(canvas) {
                                canvas.id = "mycanvas";
                                canvas.style.display = &#39;none&#39;;
                                document.body.appendChild(canvas);
                                //生成base64图片数据

                                imgData = canvas.toDataURL(type);
                                //var newImg = document.createElement("img");
                                //newImg.src =  dataUrl;
                                //document.body.appendChild(newImg);
                                //console.log(imgData);

                                var _fixType = function(type) {
                                    type = type.toLowerCase().replace(/jpg/i, &#39;jpeg&#39;);
                                    var r = type.match(/png|jpeg|bmp|gif/)[0];
                                    return &#39;image/&#39; + r;
                                };
                                // 加工image data，替换mime type
                                imgData = imgData.replace(_fixType(type),&#39;image/octet-stream&#39;);
                                /**
                                 * 在本地进行文件保存
                                 * @param  {String} data     要保存到本地的图片数据
                                 * @param  {String} filename 文件名
                                 */
                                var saveFile = function(data, filename){
                                    var save_link = document.createElementNS(&#39;http://www.w3.org/1999/xhtml&#39;, &#39;a&#39;);
                                    save_link.href = data;
                                    save_link.download = filename;

                                    var event = document.createEvent(&#39;MouseEvents&#39;);
                                    event.initMouseEvent(&#39;click&#39;, true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
                                    save_link.dispatchEvent(event);
                                };

                                // 下载后的问题名
                                var filename = aname+&#39;肌肤检测报告&#39; + (new Date()).getTime() + &#39;.&#39; + type;
                                // download
                                saveFile(imgData,filename);
                            },
                            width:1512,
                            height:15000
                        })
                    },2500)
                }
                else
                {
                    return;
                }

            })

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