• h5图片压缩上传


    1、图片上传过慢,图片进行压缩上传

    <div class="form-item item-first">
        <input type="file" id="choose" accept="image/*" multiple>
        <ul class="img-list">
          <li class="tmp-img"></li>
        </ul>
        <div id="upload">上传图片</div>
    </div>
    .item-first{display:flex;align-items:flex-end;}
    .img-list li{position:relative;display:block;margin:0 auto;margin:0 auto;width:90px;height:120px;background-color:#fff;background-position:center center;background-repeat:no-repeat;}
    .progress{position:absolute;bottom:0;left:0;width:100%;height:20px;background-color:rgba(254,61,73,.5);line-height:20px;}
    .progress span{display:block;width:0;height:100%;background-color:#fe3d49;color:#fff;text-align:center;font-size:13px;}
    .size{position:absolute;bottom:-18px;width:100%;height:15px;color:#666;text-align:center;font-size:13px;line-height:15px;}
    .tips{display:block;margin:10px;color:#999;text-align:center;font-size:13px;}
    .pic-list{margin:10px;font-size:13px;line-height:18px;}
    .pic-list a{display:block;margin:10px 0;}
    .pic-list a img{margin:-4px 0 0 10px;max-width:30px;max-height:30px;vertical-align:middle;}
    .tmp-img{margin:0 auto;width:90px;height:120px;background-color:#fff;background-image:url(../images/upload_img.png);background-size:67px 64px;}
    <script>
      var filechooser = document.getElementById("choose");
      //    用于压缩图片的canvas
      var canvas = document.createElement("canvas");
      var ctx = canvas.getContext('2d');
      //    瓦片canvas
      var tCanvas = document.createElement("canvas");
      var tctx = tCanvas.getContext("2d");
      var maxsize = 100 * 1024;
      $("#upload").on("click", function() {
            filechooser.click();
          })
          .on("touchstart", function() {
            $(this).addClass("touch")
          })
          .on("touchend", function() {
            $(this).removeClass("touch")
          });
      filechooser.onchange = function() {
        if (!this.files.length) return;
        var files = Array.prototype.slice.call(this.files);
        if (files.length > 9) {
          alert("最多同时只可上传9张图片");
          return;
        }
        files.forEach(function(file, i) {
          if (!//(?:jpeg|png|gif)/i.test(file.type)) return;
          var reader = new FileReader();
          var li = document.createElement("li");
    //          获取图片大小
          var size = file.size / 1024 > 1024 ? (~~(10 * file.size / 1024 / 1024)) / 10 + "MB" : ~~(file.size / 1024) + "KB";
          li.innerHTML = '<div class="progress"><span></span></div>';
          $(".img-list").html($(li));
          $('.img-list li').attr("style","background-image: url(../images/loading_big.gif);background-size: 60px 60px");
          reader.onload = function() {
            var result = this.result;
            var img = new Image();
            img.src = result;
            // $(li).css("background-image", "url(" + result + ")");
            //如果图片大小小于100kb,则直接上传
            if (result.length <= maxsize) {
              img = null;
              upload(result, file.type, $(li));
              return;
            }
    //      图片加载完毕之后进行压缩,然后上传
            if (img.complete) {
              callback();
            } else {
              img.onload = callback;
            }
            function callback() {
              var data = compress(img);
              upload(data, file.type, $(li));
              img = null;
            }
          };
          reader.readAsDataURL(file);
        })
      };
      //    使用canvas对大图片进行压缩
      function compress(img) {
        console.log(img);
        var initSize = img.src.length;
        var width = img.width;
        var height = img.height;
        //如果图片大于四百万像素,计算压缩比并将大小压至400万以下
        var ratio;
        if ((ratio = width * height / 4000000) > 1) {
          ratio = Math.sqrt(ratio);
          width /= ratio;
          height /= ratio;
        } else {
          ratio = 1;
        }
        canvas.width = width;
        canvas.height = height;
    //        铺底色
        ctx.fillStyle = "#fff";
        ctx.fillRect(0, 0, canvas.width, canvas.height);
        //如果图片像素大于100万则使用瓦片绘制
        var count;
        if ((count = width * height / 1000000) > 1) {
          count = ~~(Math.sqrt(count) + 1); //计算要分成多少块瓦片
    //            计算每块瓦片的宽和高
          var nw = ~~(width / count);
          var nh = ~~(height / count);
          tCanvas.width = nw;
          tCanvas.height = nh;
          for (var i = 0; i < count; i++) {
            for (var j = 0; j < count; j++) {
              tctx.drawImage(img, i * nw * ratio, j * nh * ratio, nw * ratio, nh * ratio, 0, 0, nw, nh);
              ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);
            }
          }
        } else {
          ctx.drawImage(img, 0, 0, width, height);
        }
        //进行最小压缩
        var ndata = canvas.toDataURL('image/jpeg', 0.1);
        console.log('压缩前:' + initSize);
        console.log('压缩后:' + ndata.length);
        console.log('压缩率:' + ~~(100 * (initSize - ndata.length) / initSize) + "%");
        tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
        return ndata;
      }
      //    图片上传,将base64的图片转成二进制对象,塞进formdata上传
      function upload(basestr, type, $li) {
        var text = window.atob(basestr.split(",")[1]);
        var buffer = new Uint8Array(text.length);
        var pecent = 0, loop = null;
        for (var i = 0; i < text.length; i++) {
          buffer[i] = text.charCodeAt(i);
        }
        var blob = getBlob([buffer], type);
        var xhr = new XMLHttpRequest();
        var formdata = getFormData();
        formdata.append('file', blob);
        xhr.open('post', '上传图片地址url');
        xhr.onreadystatechange = function() {
          
          if (xhr.readyState == 4 && xhr.status == 200) {
            var jsonData = JSON.parse(xhr.responseText);
            var imagedata = jsonData.data || {};
            var text = imagedata.url ? '上传成功' : '上传失败';
            console.log(text + ':' + imagedata.url);
            $('.img-list li').attr("style","background-image: url("+imagedata.url+");background-size: 100% 100%");
            $('#upload').attr('data-picId',imagedata.url);
            clearInterval(loop);
            //当收到该消息时上传完毕
            $li.find(".progress span").animate({'width': "100%"}, pecent < 95 ? 200 : 0, function() {
              $(this).html(text);
            });
            if (!imagedata.path) return;
            $(".pic-list").append('<a href="' + imagedata.path + '">' + imagedata.name + '(' + imagedata.size + ')<img src="' + imagedata.path + '" /></a>');
          }
        };
        //数据发送进度,前50%展示该进度
        xhr.upload.addEventListener('progress', function(e) {
          if (loop) return;
          pecent = ~~(100 * e.loaded / e.total) / 2;
          $li.find(".progress span").css('width', pecent + "%");
          if (pecent == 50) {
            mockProgress();
          }
        }, false);
        //数据后50%用模拟进度
        function mockProgress() {
          if (loop) return;
          loop = setInterval(function() {
            pecent++;
            $li.find(".progress span").css('width', pecent + "%");
            if (pecent == 99) {
              clearInterval(loop);
            }
          }, 100)
        }
        xhr.send(formdata);
      }
      /**
       * 获取blob对象的兼容性写法
       * @param buffer
       * @param format
       * @returns {*}
       */
      function getBlob(buffer, format) {
        try {
          return new Blob(buffer, {type: format});
        } catch (e) {
          var bb = new (window.BlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder);
          buffer.forEach(function(buf) {
            bb.append(buf);
          });
          return bb.getBlob(format);
        }
      }
      /**
       * 获取formdata
       */
      function getFormData() {
        var isNeedShim = ~navigator.userAgent.indexOf('Android')
            && ~navigator.vendor.indexOf('Google')
            && !~navigator.userAgent.indexOf('Chrome')
            && navigator.userAgent.match(/AppleWebKit/(d+)/).pop() <= 534;
        return isNeedShim ? new FormDataShim() : new FormData()
      }
      /**
       * formdata 补丁, 给不支持formdata上传blob的android机打补丁
       * @constructor
       */
      function FormDataShim() {
        console.warn('using formdata shim');
        var o = this,
            parts = [],
            boundary = Array(21).join('-') + (+new Date() * (1e16 * Math.random())).toString(36),
            oldSend = XMLHttpRequest.prototype.send;
        this.append = function(name, value, filename) {
          parts.push('--' + boundary + '
    Content-Disposition: form-data; name="' + name + '"');
          if (value instanceof Blob) {
            parts.push('; filename="' + (filename || 'blob') + '"
    Content-Type: ' + value.type + '
    
    ');
            parts.push(value);
          }
          else {
            parts.push('
    
    ' + value);
          }
          parts.push('
    ');
        };
        // Override XHR send()
        XMLHttpRequest.prototype.send = function(val) {
          var fr,
              data,
              oXHR = this;
          if (val === o) {
            // Append the final boundary string
            parts.push('--' + boundary + '--
    ');
            // Create the blob
            data = getBlob(parts);
            // Set up and read the blob into an array to be sent
            fr = new FileReader();
            fr.onload = function() {
              oldSend.call(oXHR, fr.result);
            };
            fr.onerror = function(err) {
              throw err;
            };
            fr.readAsArrayBuffer(data);
            // Set the multipart content type and boudary
            this.setRequestHeader('Content-Type', 'multipart/form-data; boundary=' + boundary);
            XMLHttpRequest.prototype.send = oldSend;
          }
          else {
            oldSend.call(this, val);
          }
        };
      }
    </script>
    与尘埃中开出花朵。
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  • 原文地址:https://www.cnblogs.com/congfeicong/p/11143183.html
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