我正在構建一個Ionic2應用程序。我正在嘗試將圖像url轉換爲base64圖像。我發現this,我正在嘗試使用。Javascript將URL轉換爲BASE64圖像
我有以下代碼:
var imgUrl = 'https://www.google.de/images/srpr/logo11w.png';
let base64image = this.getBase64Image(imgUrl);
console.log(base64image);
和
public getBase64Image(imgUrl) {
var img = new Image();
img.src = imgUrl;
img.setAttribute('crossOrigin', 'anonymous');
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
var dataURL = canvas.toDataURL("image/png");
return dataURL.replace(/^data:image\/(png|jpg);base64,/, "");
}
但是,它輸出以下:
data:,
我沒有得到任何錯誤,但想到一個base64形象。
我的代碼必須是不正確的。任何人都可以請建議如何將網址轉換爲base64圖像?
感謝
UPDATE
謝謝你從下面的傢伙的反饋,我也跟着他們奉勸機智的圖像加載。現在,我有以下代碼:
public getBase64Image(imgUrl): Promise<string> {
return new Promise<string>(resolve => {
var img = new Image();
img.src = imgUrl;
img.setAttribute('crossOrigin', 'anonymous');
img.onload = (() => {
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
var dataURL = canvas.toDataURL("image/png");
//console.log('UgetBase64Image.dataURL ', dataURL);
resolve(dataURL.replace(/^data:image\/(png|jpg);base64,/, ""));
});
});
}
用法:
let promise64: Promise<string> = this.getBase64Image(personModel.avatar);
promise64.then((data) => {
personModel.avatar64 = data;
});
這似乎當我運行的console.log創建一個base64形象。
不過,我得到以下錯誤:
Error: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported. at HTMLImageElement.img.onload (utilityService.ts:80)
80號線:var dataURL = canvas.toDataURL("image/png");
我還以爲下面的代碼將解決這個安全問題,但無濟於事:
img.setAttribute('crossOrigin', 'anonymous');
更多信息:
全部錯誤:
:8100/iVBORw0KGgoAAAANSUhEUgAAAbgAAAG5CAYAAAD8liEWAAAgAElEQVR4Xty9B3NkR5Ksm…bNkFj80enI0JnJ80+gTsx2sbrX9zhp7k1oOOPZ5K7Oh/AvN0hP6tzZ6QAAAAAElFTkSuQmCC:1 GET http://localhost:8100/iVBORw0KGgoAAAANSUhEUgAAAbgAAAG5CAYAAAD8liEWAAAgAElEQ…t3bNkFj80enI0JnJ80+gTsx2sbrX9zhp7k1oOOPZ5K7Oh/AvN0hP6tzZ6QAAAAAElFTkSuQmCC net::ERR_EMPTY_RESPONSE
polyfills.js:3 POST http://localhost:8080/jbosswildfly-1.0/person/updatetime 400 (Bad Request)
e @ polyfills.js:3
t.scheduleTask @ polyfills.js:3
e.scheduleMacroTask @ polyfills.js:3
(anonymous) @ polyfills.js:3
send @ VM9549:3
(anonymous) @ xhr_backend.js:117
Observable.subscribe @ Observable.js:45
MapOperator.call @ map.js:54
Observable.subscribe @ Observable.js:42
(anonymous) @ personService.ts:141
t @ polyfills.js:3
PersonService.updateTimeStamps @ personService.ts:140
(anonymous) @ searchjobsParent.ts:109
t.invoke @ polyfills.js:3
onInvoke @ ng_zone.js:236
t.invoke @ polyfills.js:3
onInvoke @ ng_zone.js:236
t.invoke @ polyfills.js:3
e.run @ polyfills.js:3
(anonymous) @ polyfills.js:3
t.invokeTask @ polyfills.js:3
onInvokeTask @ ng_zone.js:227
t.invokeTask @ polyfills.js:3
onInvokeTask @ ng_zone.js:227
t.invokeTask @ polyfills.js:3
e.runTask @ polyfills.js:3
i @ polyfills.js:3
polyfills.js:3 GET http://localhost:8080/jbosswildfly-1.0/person/list/favouritejob/null/0/ 400 (Bad Request)
EXCEPTION: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.
ErrorHandler.handleError @ error_handler.js:47
IonicErrorHandler.handleError @ ionic-error-handler.js:56
next @ application_ref.js:272
schedulerFn @ async.js:82
SafeSubscriber.__tryOrUnsub @ Subscriber.js:223
SafeSubscriber.next @ Subscriber.js:172
Subscriber._next @ Subscriber.js:125
Subscriber.next @ Subscriber.js:89
Subject.next @ Subject.js:55
EventEmitter.emit @ async.js:74
NgZone.triggerError @ ng_zone.js:278
onHandleError @ ng_zone.js:257
t.handleError @ polyfills.js:3
e.runTask @ polyfills.js:3
invoke @ polyfills.js:3
error_handler.js:52 ORIGINAL STACKTRACE:
ErrorHandler.handleError @ error_handler.js:52
IonicErrorHandler.handleError @ ionic-error-handler.js:56
next @ application_ref.js:272
schedulerFn @ async.js:82
SafeSubscriber.__tryOrUnsub @ Subscriber.js:223
SafeSubscriber.next @ Subscriber.js:172
Subscriber._next @ Subscriber.js:125
Subscriber.next @ Subscriber.js:89
Subject.next @ Subject.js:55
EventEmitter.emit @ async.js:74
NgZone.triggerError @ ng_zone.js:278
onHandleError @ ng_zone.js:257
t.handleError @ polyfills.js:3
e.runTask @ polyfills.js:3
invoke @ polyfills.js:3
error_handler.js:53 Error: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.
at HTMLImageElement.img.onload (utilityService.ts:82)
at HTMLImageElement.n [as _onload] (polyfills.js:2)
at t.invokeTask (polyfills.js:3)
at Object.onInvokeTask (ng_zone.js:227)
at t.invokeTask (polyfills.js:3)
at e.runTask (polyfills.js:3)
at HTMLImageElement.invoke (polyfills.js:3)
等待圖像加載使用'img.onload' –
感謝亞當,在什麼時候,我必須這樣做嗎?在創建Canvas之前? – Richard
你得到這個錯誤的圖像的URL是什麼? –