html2canvas/src/Proxy.js
2017-09-25 22:53:09 +08:00

63 lines
2.2 KiB
JavaScript

/* @flow */
'use strict';
import type Options from './index';
import FEATURES from './Feature';
export const Proxy = (src: string, options: Options): Promise<string> => {
if (!options.proxy) {
return Promise.reject(__DEV__ ? 'No proxy defined' : null);
}
const proxy = options.proxy;
return new Promise((resolve, reject) => {
const responseType =
FEATURES.SUPPORT_CORS_XHR && FEATURES.SUPPORT_RESPONSE_TYPE ? 'blob' : 'text';
const xhr = FEATURES.SUPPORT_CORS_XHR ? new XMLHttpRequest() : new XDomainRequest();
xhr.onload = () => {
if (xhr instanceof XMLHttpRequest) {
if (xhr.status === 200) {
if (responseType === 'text') {
resolve(xhr.response);
} else {
const reader = new FileReader();
// $FlowFixMe
reader.addEventListener('load', () => resolve(reader.result), false);
// $FlowFixMe
reader.addEventListener('error', e => reject(e), false);
reader.readAsDataURL(xhr.response);
}
} else {
reject(
__DEV__
? `Failed to proxy resource ${src.substring(
0,
256
)} with status code ${xhr.status}`
: ''
);
}
} else {
resolve(xhr.responseText);
}
};
xhr.onerror = reject;
xhr.open('GET', `${proxy}?url=${encodeURIComponent(src)}&responseType=${responseType}`);
if (responseType !== 'text' && xhr instanceof XMLHttpRequest) {
xhr.responseType = responseType;
}
if (options.imageTimeout) {
const timeout = options.imageTimeout;
xhr.timeout = timeout;
xhr.ontimeout = () =>
reject(__DEV__ ? `Timed out (${timeout}ms) proxying ${src.substring(0, 256)}` : '');
}
xhr.send();
});
};