feat(base64 file converter): add a preview image

Fix CorentinTh#594. Taken from CorentinTh#595 (thanks @SAF2k)

Author: sharevb

src/composable/downloadBase64.ts

@@ -6,6 +6,7 @@ export {
   getMimeTypeFromBase64,
   getMimeTypeFromExtension, getExtensionFromMimeType,
   useDownloadFileFromBase64, useDownloadFileFromBase64Refs,
+  previewImageFromBase64,
 };
 
 const commonMimeTypesSignatures = {
@@ -92,3 +93,26 @@ function useDownloadFileFromBase64Refs(
     },
   };
 }
+
+function previewImageFromBase64(base64String: string): HTMLImageElement {
+  if (base64String === '') {
+    throw new Error('Base64 string is empty');
+  }
+
+  const img = document.createElement('img');
+  img.src = base64String;
+
+  const container = document.createElement('div');
+  container.appendChild(img);
+
+  const previewContainer = document.getElementById('previewContainer');
+  if (previewContainer) {
+    previewContainer.innerHTML = '';
+    previewContainer.appendChild(container);
+  }
+  else {
+    throw new Error('Preview container element not found');
+  }
+
+  return img;
+}

src/tools/base64-file-converter/base64-file-converter.vue

@@ -2,7 +2,7 @@
 import { useBase64 } from '@vueuse/core';
 import type { Ref } from 'vue';
 import { useCopy } from '@/composable/copy';
-import { getExtensionFromMimeType, getMimeTypeFromBase64, useDownloadFileFromBase64Refs } from '@/composable/downloadBase64';
+import { getExtensionFromMimeType, getMimeTypeFromBase64, previewImageFromBase64, useDownloadFileFromBase64Refs } from '@/composable/downloadBase64';
 import { useValidation } from '@/composable/validation';
 import { isValidBase64 } from '@/utils/base64';
 
@@ -35,6 +35,25 @@ watch(
   },
 );
 
+function previewImage() {
+  if (!base64InputValidation.isValid) {
+    return;
+  }
+  try {
+    const image = previewImageFromBase64(base64Input.value);
+    image.style.maxWidth = '100%';
+    image.style.maxHeight = '400px';
+    const previewContainer = document.getElementById('previewContainer');
+    if (previewContainer) {
+      previewContainer.innerHTML = '';
+      previewContainer.appendChild(image);
+    }
+  }
+  catch (_) {
+    //
+  }
+}
+
 function downloadFile() {
   if (!base64InputValidation.isValid) {
     return;
@@ -88,7 +107,14 @@ async function onUpload(file: File) {
       mb-2
     />
 
-    <div flex justify-center>
+    <div flex justify-center py-2>
+      <div id="previewContainer" />
+    </div>
+
+    <div flex justify-center gap-3>
+      <c-button :disabled="base64Input === '' || !base64InputValidation.isValid" @click="previewImage()">
+        Preview image
+      </c-button>
       <c-button :disabled="base64Input === '' || !base64InputValidation.isValid" @click="downloadFile()">
         Download file
       </c-button>