我正在尝试将一个非常简单的JS库导入Angular 2.这就是库的样子：
JIC.js
var jic = {
/**
* Receives an Image Object (can be JPG OR PNG) and returns a new Image Object compressed
* @param {Image} source_img_obj The source Image Object
* @param {Integer} quality The output quality of Image Object
* @param {String} output format. Possible values are jpg and png
* @return {Image} result_image_obj The compressed Image Object
*/
compress: function(source_img_obj, quality, output_format){
var mime_type = "image/jpeg";
if(typeof output_format !== "undefined" && output_format=="png"){
mime_type = "image/png";
}
var cvs = document.createElement('canvas');
cvs.width = source_img_obj.naturalWidth;
cvs.height = source_img_obj.naturalHeight;
var ctx = cvs.getContext("2d").drawImage(source_img_obj, 0, 0);
var newImageData = cvs.toDataURL(mime_type, quality/100);
var result_image_obj = new Image();
result_image_obj.src = newImageData;
return result_image_obj;
},
/**
* Receives an Image Object and upload it to the server via ajax
* @param {Image} compressed_img_obj The Compressed Image Object
* @param {String} The server side url to send the POST request
* @param {String} file_input_name The name of the input that the server will receive with the file
* @param {String} filename The name of the file that will be sent to the server
* @param {function} successCallback The callback to trigger when the upload is succesful.
* @param {function} (OPTIONAL) errorCallback The callback to trigger when the upload failed.
* @param {function} (OPTIONAL) duringCallback The callback called to be notified about the image's upload progress.
* @param {Object} (OPTIONAL) customHeaders An object representing key-value properties to inject to the request header.
*/
upload: function(compressed_img_obj, upload_url, file_input_name, filename, successCallback, errorCallback, duringCallback, customHeaders){
//ADD sendAsBinary compatibilty to older browsers
if (XMLHttpRequest.prototype.sendAsBinary === undefined) {
XMLHttpRequest.prototype.sendAsBinary = function(string) {
var bytes = Array.prototype.map.call(string, function(c) {
return c.charCodeAt(0) & 0xff;
});
this.send(new Uint8Array(bytes).buffer);
};
}
var type = "image/jpeg";
if(filename.substr(-4).toLowerCase()==".png"){
type = "image/png";
}
var data = compressed_img_obj.src;
data = data.replace('data:' + type + ';base64,', '');
var xhr = new XMLHttpRequest();
xhr.open('POST', upload_url, true);
var boundary = 'someboundary';
xhr.setRequestHeader('Content-Type', 'multipart/form-data; boundary=' + boundary);
// Set custom request headers if customHeaders parameter is provided
if (customHeaders && typeof customHeaders === "object") {
for (var headerKey in customHeaders){
xhr.setRequestHeader(headerKey, customHeaders[headerKey]);
}
}
// If a duringCallback function is set as a parameter, call that to notify about the upload progress
if (duringCallback && duringCallback instanceof Function) {
xhr.upload.onprogress = function (evt) {
if (evt.lengthComputable) {
duringCallback ((evt.loaded / evt.total)*100);
}
};
}
xhr.sendAsBinary(['--' + boundary, 'Content-Disposition: form-data; name="' + file_input_name + '"; filename="' + filename + '"', 'Content-Type: ' + type, '', atob(data), '--' + boundary + '--'].join('\r\n'));
xhr.onreadystatechange = function() {
if (this.readyState == 4){
if (this.status == 200) {
successCallback(this.responseText);
}else if (this.status >= 400) {
if (errorCallback && errorCallback instanceof Function) {
errorCallback(this.responseText);
}
}
}
};
}
};
到目前为止，我已经尝试过这个：
npm install j-i-c --save
在打字稿文件中，我想使用它：
import * as jic from 'j-i-c';
在我的app.component.ts中：
declare var jic: any;。
当我运行它并尝试记录全局变量jic时，它只是一个空对象{}。我假设这是因为我需要一个打字定义，我需要帮助 - 但我也想知道是否需要重写JIC.js。我尝试导出两个函数compress和upload并删除jic对象声明，如下所示：
export function compress(source_img_obj, quality, output_format){
var mime_type = "image/jpeg";
if(typeof output_format !== "undefined" && output_format=="png"){
mime_type = "image/png";
}
var cvs = document.createElement('canvas');
cvs.width = source_img_obj.naturalWidth;
cvs.height = source_img_obj.naturalHeight;
var ctx = cvs.getContext("2d").drawImage(source_img_obj, 0, 0);
var newImageData = cvs.toDataURL(mime_type, quality/100);
var result_image_obj = new Image();
result_image_obj.src = newImageData;
return result_image_obj;
};
/**
* Receives an Image Object and upload it to the server via ajax
* @param {Image} compressed_img_obj The Compressed Image Object
* @param {String} The server side url to send the POST request
* @param {String} file_input_name The name of the input that the server will receive with the file
* @param {String} filename The name of the file that will be sent to the server
* @param {function} successCallback The callback to trigger when the upload is succesful.
* @param {function} (OPTIONAL) errorCallback The callback to trigger when the upload failed.
* @param {function} (OPTIONAL) duringCallback The callback called to be notified about the image's upload progress.
* @param {Object} (OPTIONAL) customHeaders An object representing key-value properties to inject to the request header.
*/
export function upload(compressed_img_obj, upload_url, file_input_name, filename, successCallback, errorCallback, duringCallback, customHeaders){
//ADD sendAsBinary compatibilty to older browsers
if (XMLHttpRequest.prototype.sendAsBinary === undefined) {
XMLHttpRequest.prototype.sendAsBinary = function(string) {
var bytes = Array.prototype.map.call(string, function(c) {
return c.charCodeAt(0) & 0xff;
});
this.send(new Uint8Array(bytes).buffer);
};
}
var type = "image/jpeg";
if(filename.substr(-4).toLowerCase()==".png"){
type = "image/png";
}
var data = compressed_img_obj.src;
data = data.replace('data:' + type + ';base64,', '');
var xhr = new XMLHttpRequest();
xhr.open('POST', upload_url, true);
var boundary = 'someboundary';
xhr.setRequestHeader('Content-Type', 'multipart/form-data; boundary=' + boundary);
// Set custom request headers if customHeaders parameter is provided
if (customHeaders && typeof customHeaders === "object") {
for (var headerKey in customHeaders){
xhr.setRequestHeader(headerKey, customHeaders[headerKey]);
}
}
// If a duringCallback function is set as a parameter, call that to notify about the upload progress
if (duringCallback && duringCallback instanceof Function) {
xhr.upload.onprogress = function (evt) {
if (evt.lengthComputable) {
duringCallback ((evt.loaded / evt.total)*100);
}
};
}
xhr.sendAsBinary(['--' + boundary, 'Content-Disposition: form-data; name="' + file_input_name + '"; filename="' + filename + '"', 'Content-Type: ' + type, '', atob(data), '--' + boundary + '--'].join('\r\n'));
xhr.onreadystatechange = function() {
if (this.readyState == 4){
if (this.status == 200) {
successCallback(this.responseText);
}else if (this.status >= 400) {
if (errorCallback && errorCallback instanceof Function) {
errorCallback(this.responseText);
}
}
}
};
那么，为什么记录到控制台的对象为空？如何正确导入此库？此外，我试图这样做，因为我找不到可用的angular2 /离子图像压缩包。我发现ng2-img-tools - 但是有一个问题 - 图像文件没有类型属性（它是null而不是image/jpeg，这使得它无法压缩。
答案 0 :(得分：1)
根据github中的这个问题
https://github.com/brunobar79/J-I-C/issues/47
你不能按原样导入它。
您必须在缩小版本中进行非常简单的修改才能将其作为模块“需要”：
在j-i-c/dist/JIC.min.js，
你可以改变
var jic =
通过
module.exports =
在导入组件文件后，您可以编写
import * as jicLib from 'j-i-c/dist/JIC.min';
declare const jib:any = jicLib;';
并随时使用jib.compress()