From c3bc52bcc413a16ff7f4057e6640e6817c1ef9d8 Mon Sep 17 00:00:00 2001
From: Patrizio Bekerle <patrizio@bekerle.com>
Date: Fri, 5 Jun 2020 07:35:02 +0200
Subject: [PATCH] Add function getMimeTypeOfFile (VPU/Apps/Signature#11)
---
packages/common/utils.js | 49 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/packages/common/utils.js b/packages/common/utils.js
index eeac3fd1..a6e961d6 100644
--- a/packages/common/utils.js
+++ b/packages/common/utils.js
@@ -278,3 +278,52 @@ export async function asyncArrayForEach(array, callback) {
await callback(array[index], index, array);
}
}
+
+/**
+ * Attempts to determine the mime type of a file or blob
+ *
+ * @param file
+ * @returns {Promise<unknown>}
+ */
+export async function getMimeTypeOfFile(file) {
+ const getMimeType = (signature) => {
+ switch (signature) {
+ case '89504E47':
+ return 'image/png'
+ case '47494638':
+ return 'image/gif'
+ case '25504446':
+ return 'application/pdf'
+ case 'FFD8FFDB':
+ case 'FFD8FFE0':
+ case 'FFD8FFE1':
+ return 'image/jpeg'
+ case '504B0304':
+ return 'application/zip'
+ default:
+ return 'Unknown filetype'
+ }
+ }
+
+ return await new Promise((resolve) => {
+ let fileReader = new FileReader();
+
+ fileReader.onloadend = function (evt) {
+ if (evt.target.readyState === FileReader.DONE) {
+ const uint = new Uint8Array(evt.target.result);
+ let bytes = [];
+
+ uint.forEach((byte) => {
+ bytes.push(byte.toString(16))
+ })
+
+ const hex = bytes.join('').toUpperCase();
+ const mimeType = getMimeType(hex);
+
+ resolve(mimeType);
+ }
+ }
+
+ fileReader.readAsArrayBuffer(file.slice(0, 4));
+ });
+}
--
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