我正在尝试构建一个 Flask 应用程序,我在其中上传 pdf 文件,并且我正在努力在提交到后端之前预览它们。
我使用的脚本如下:
const imageUploadValidation = (function () {
"use strict";
pdfjsLib.GlobalWorkerOptions.workerSrc =
"https://mozilla.github.io/pdf.js/build/pdf.js";
const onFilePicked = function (event) {
// Select file Nodelist containing 1 file
const files = event.target.files;
const filename = files[0].name;
if (filename.lastIndexOf(".") <= 0) {
return alert("Please add a valid file!");
}
const fileReader = new FileReader();
fileReader.onload = function (e) {
const pdfData = e.target.result;
let loadingTask = pdfjsLib.getDocument({ data: pdfData })
loadingTask.promise.then(function (pdf) {
console.log("PDF loaded", pdf);
pdf.getPage(1).then((page) => {
console.log("page loaded", page);
// var scale = 1.5;
// var viewport = page.getViewport({ scale: scale });
var iframe = document.getElementById("image-preview");
iframe.src = page
// var context = canvas.getContext("2d");
// canvas.height = viewport.height;
// canvas.width = viewport.width;
// var renderContext = {
// canvasContext: context,
// viewport: viewport,
// };
// var renderTask = page.render(renderContext);
// renderTask.promise.then(function () {
// console.log("Page rendered");
// });
});
})
.catch((error) => {
console.log(error);
});
};
const pdf = fileReader.readAsArrayBuffer(files[0]);
console.log("read as Data URL", pdf);
};
const Constructor = function (selector) {
const publicAPI = {};
const changeHandler = (e) => {
// console.log(e)
onFilePicked(e);
};
publicAPI.init = function (selector) {
// Check for errors.
const fileInput = document.querySelector(selector);
if (!selector || typeof selector !== "string") {
throw new Error("Please provide a valid selector");
}
fileInput.addEventListener("change", changeHandler);
};
publicAPI.init(selector);
return publicAPI;
};
return Constructor;
})();
imageUploadValidation("form input[type=file]");
加载任务承诺似乎永远不会运行。直到那时,一切似乎都正常。我不熟悉这个 Promise 语法,所以我不能确定问题是否存在或者我是如何传入 pdf 文件的。
PS 注释掉的代码是我进行此设置的原始方式,未注释的只是我测试不同的方式。