[H5-Compress-Image]利用canvas实现 javascript 图片压缩处理_基于requirejs模块化的代码实现

// 还存在有问题的代码，问题在于processFile()中
// 问题：在ipone 5c 下，某些图片压缩处理后，上传到服务器生成的文件size为0，即是空白

;define(['mod/tool/formSubmit'] ,function(o_formSubmit) {

    return {
        
        init: function(id) {
            var self = this;
            self.sniff(id);
            var $img = '';
            var $inputField = '';
        },
        sniff: function(id) {
            var self = this;
            if (window.File && window.FileReader && window.FormData) {
                
                $inputField = $('#' + id);
            
                $inputField.on('change', function (e) {
    
                    var file = e.target.files[0];
                    if($('.c-img-wrap').length >= 9)
                    {
                        Hnb.ui.showError('不能上传超过9张图片' , 3000);
                        return ;
                    }
                    
                    if (file) {
                        //alert(file.type);
                        //if(!file.type) file.type='image/jpeg';
                        //if (/^image//i.test(file.type)) {
                            if($("#id_img_list").parent().attr("scrollWidth") > $(window).width())
                            {
                                $("#id_img_list").parent().scrollLeft($("#id_img_list").parent().attr("scrollWidth") - $(window).width());
                            }
                            $img = $('<a class="bg c-img-wrap" href="javascript:void(null);"><i class="pa  c-img-close"></i></a>').insertBefore($("#id_last_img_wrap"));
                            
                            self.readFile(file);
                        //} else {
                        //    Hnb.ui.showError('请在浏览器中打开该页面上传图片' , 3000);
                        //    $inputField.val('');
                        //}
                    }
                    
                });
                $inputField.val('');
            } else {
                Hnb.ui.showError("当前您的浏览器不支持图片上传，请选择其他的浏览器进行上传。" , 3000);
                $inputField.val('');
            }
        },
        
        readFile: function (file) {
            var self = this;
            var reader = new FileReader();
            var head = '';
            reader.onloadend = function () {
            //reader.onload = function () {
                head = reader.result.substr(0, 20);
                alert('head:' + head);
                alert('file_type:' + file.type);
                self.processFile(reader.result, file.type);
            }

            reader.onerror = function () {
                Hnb.ui.showError('上传图片过程中发生了网络异常，请稍后重试。' , 3000);
            }

            reader.readAsDataURL(file);
        },
        processFile: function (dataURL, fileType) {
            
            var self = this;
            var maxWidth = 3120;
            var maxHeight = 4208;

            var image = new Image();
            image.src = dataURL;

            image.onload = function () {
                var width = image.width;
                var height = image.height;
                var shouldResize = (width > maxWidth) || (height > maxHeight);

                if (!shouldResize) {
                    //self.submitFile(dataURL);
                    self.sendFile(dataURL , fileType);
                    return;
                }

                var newWidth;
                var newHeight;

                if (width > height) {
                    newHeight = height * (maxWidth / width);
                    newWidth = maxWidth;
                } else {
                    newWidth = width * (maxHeight / height);
                    newHeight = maxHeight;
                }

                var canvas = document.createElement('canvas');

                canvas.width = newWidth;
                canvas.height = newHeight;

                var context = canvas.getContext('2d');

                context.drawImage(this, 0, 0, newWidth, newHeight);

                dataURL = canvas.toDataURL(fileType);
                alert(dataURL.length);
                //window.location = dataURL;
                //self.sendFile(dataURL , fileType);
                /*
                var file = canvas.mozGetAsFile("foo.png");
                var f = document.createElement("form");
                var i = document.createElement("input"); //input element, text
                i.setAttribute('type',"file");
                i.setAttribute('name',"upfile");
                i.setAttribute('value' , dataURL);
                f.appendChild(i);
                */
                //$("#id_upfile").val(dataURL);
                //document.forms[0].upfile.val = dataURL;
                //window.location = dataURL;
                
                //var formData = new FormData(document.forms[0]);
                //console.log(document.forms[0]);
                //console.log(formData.get('upfile'));
                //console.log(formData);
                //return;
                //formData.append('imageData', dataURL);
                //formData.delete('upfile');
                //console.log($inputField.files);
                //formData.set('upfile', $inputField.files[0] , dataURL);
                //self.submitFile($(f));
            };

            image.onerror = function () {
                //alert('There was an error processing your file!');
                Hnb.ui.showError('上传图片处理过程中发生了网络异常，请稍后重试。' , 3000);
            };
        },
        submitFile: function(f) {
            var self = this;
            //console.log(f);
            o_formSubmit.create(f , Hnb.WWW_CGI_URL + "/image/saveInCrossDomain").start().done(function(json_msg){
                if(json_msg.state || !json_msg.data.real_url) {
                    Hnb.ui.showError("上传图片失败！" ,  3000);
                    $img.remove();
                } else {
                    
                    console.log(json_msg.data);
                    
                    $img.removeClass("bg").addClass("comBg").css("background-image" , "url(" + json_msg.data.real_url + ")").attr("hnb-src" , json_msg.data.real_url);
                    //$img.html('<img src="' + json_msg.data.real_url + '" alt="帖子图片">');
                    $("#id_top_wrap").addClass("active");
                    //$img.html("");
                }					
            }).fail(function(json_error){
                $img.remove();
                Hnb.ui.showError("您的网络有点慢，请稍后重试" , 3000);
            }).always(function(){
                $img.removeClass("bg");
                self.isSubmitingImgNum--;
            });		
        },        
        sendFile: function (fileData , fileType) {

            var formData = new FormData();

            formData.append('imageData', fileData);
            formData.append('imageType' , fileType);
            
            $.ajax({
                type: 'POST',
                timeout: 300000,
                url: Hnb.WWW_CGI_URL + '/image/saveCndCompressImage',
                data: formData,
                contentType: false,
                processData: false,
                success: function (json_msg) {
                    //console.log('返回json数据' + json_msg);
                    var json_msg = $.parseJSON(json_msg);
                    if(!json_msg.state)
                    {
			// 跨域请求处理
                        document.domain = 'hinabian.com';
			// 可以将上传到线上的图片，追加到预览图位置
			// ...
                    } else {
                        Hnb.ui.showError('您的网络有点慢，请稍后再上传。' , 3000);
                    }
                },
                error: function (json_msg) {
                     Hnb.ui.showError('上传图片发生了网络异常，请稍后重试。' , 3000);;
                }
            }).always(
                function() {
                    $inputField.val("");
                    $img.removeClass("bg");
                }
            );
            
        }
    }
});

// 修改后，可以正常使用的代码

;define(['mod/tool/formSubmit'] ,function(o_formSubmit) {

    return {
        
        init: function(id) {
            var self = this;
            self.sniff(id);
            var $img = '';
            var $inputField = '';
        },
        sniff: function(id) {
            var self = this;
            if (window.File && window.FileReader && window.FormData) {
                
                $inputField = $('#' + id);
                $inputField.on('change', function (e) {
    
                    var file = e.target.files[0];
                    if($('.c-img-wrap').length >= 9)
                    {
                        Hnb.ui.showError('不能上传超过9张图片' , 3000);
                        return ;
                    }
                        
                    if (file) {
                        //if(!file.type) file.type='image/jpeg';
                        //if (/^image//i.test(file.type)) {
                        if($("#id_img_list").parent().attr("scrollWidth") > $(window).width())
                        {
                            $("#id_img_list").parent().scrollLeft($("#id_img_list").parent().attr("scrollWidth") - $(window).width());
                        }
                        $img = $('<a class="bg c-img-wrap" href="javascript:void(null);"><i class="pa  c-img-close"></i></a>').insertBefore($("#id_last_img_wrap"));
                        
                        self.readFile(file);
                    }
                });
            } else {
                Hnb.ui.showError("当前您的浏览器不支持图片上传，请选择其他的浏览器进行上传。", 3000);
                //$inputField.val('');
            }
            $inputField.val('');
        },
        
        readFile: function (file) {
            var self = this;
            var reader = new FileReader();
            var head = '';
            reader.onloadend = function () {
            //reader.onload = function () {
                //head = reader.result.substr(0, 20);
                self.processFile(reader.result, file.type);
            }

            reader.onerror = function () {
                Hnb.ui.showError('上传图片过程中发生了网络异常，请稍后重试。', 3000);
                return;
            }

            reader.readAsDataURL(file);
            $inputField.val('');
        },
        
        processFile: function (dataURL, fileType) {
            var self = this;
            var unitSize = 480;

            var image = new Image();
            image.src = dataURL;

            image.onload = function () {
                var wFactor = image.width / unitSize;
                var hFactor = image.height / unitSize;
                var minFactor = Math.round(Math.min(wFactor, hFactor));

                if (minFactor < 2) {
                    //self.submitFile(dataURL);
                    self.sendFile(dataURL, fileType);
                    return;
                }

                var newWidth = image.width / minFactor;
                var newHeight = image.height / minFactor;
                var canvas = document.createElement('canvas');
                canvas.width = newWidth;
                canvas.height = newHeight;

                var context = canvas.getContext('2d');
                context.drawImage(this, 0, 0, newWidth, newHeight);

                dataURL = canvas.toDataURL(fileType);
                //window.location = dataURL;
                self.sendFile(dataURL, fileType);
            };

            image.onerror = function () {
                Hnb.ui.showError('上传图片处理过程中发生了网络异常，请稍后重试。' , 3000);
                $inputField.val('');
            };
        },
        
        submitFile: function(f) {
            var self = this;
            o_formSubmit.create(f , Hnb.WWW_CGI_URL + "/image/saveInCrossDomain").start().done(function(json_msg){
                if(json_msg.state || !json_msg.data.real_url) {
                    Hnb.ui.showError("上传图片失败！" ,  3000);
                    $img.remove();
                } else {
                    $img.removeClass("bg").addClass("comBg").css("background-image" , "url(" + json_msg.data.real_url + ")").attr("hnb-src" , json_msg.data.real_url);
                    //$img.html('<img src="' + json_msg.data.real_url + '" alt="帖子图片">');
                    $("#id_top_wrap").addClass("active");
                    //$img.html("");
                }					
            }).fail(function(json_error){
                $img.remove();
                Hnb.ui.showError("您的网络有点慢，请稍后重试" , 3000);
            }).always(function(){
                $img.removeClass("bg");
                self.isSubmitingImgNum--;
                
            });		
        },        
        
        sendFile: function (fileData , fileType) {

            var formData = new FormData();
            formData.append('imageData', fileData);
            formData.append('imageType' , fileType);
            
            $.ajax({
                type: 'POST',
                timeout: 300000,
                url: Hnb.WWW_CGI_URL + '/image/saveCndCompressImage',
                data: formData,
                contentType: false,
                processData: false,
                success: function (json_msg) {
                    var json_msg = $.parseJSON(json_msg);
                    if(!json_msg.state)
                    {
                        document.domain = 'hinabian.com';
                        $img.removeClass("bg").addClass("comBg").css("background-image" , "url(" + json_msg.data.real_url + ")").attr("hnb-src" , json_msg.data.real_url);
						//$img.html('<img src="' + json_msg.data.real_url + '" alt="帖子图片">');
                        $("#id_top_wrap").addClass("active");
                    } else {
                        Hnb.ui.showError('您的网络有点慢，请稍后再上传。' , 3000);
                    }
                },
                error: function (json_msg) {
                     Hnb.ui.showError('上传图片发生了网络异常，请稍后重试。' , 3000);;
                }
            }).always(
                function() {
                    $inputField.val("");
                    $img.removeClass("bg");
                }
            );
        }
    }
});