Export note with local images

Looks through the note and searches for local images. Copies them to ‘images’ folder in the export path and replaces affected links.

#1261

browser/main/lib/dataApi/exportImage.js

@@ -0,0 +1,37 @@
+const fs = require('fs')
+const path = require('path')
+
+/**
+ * @description Export an image
+ * @param {String} storagePath
+ * @param {String} srcFilename
+ * @param {String} dstPath
+ * @param {String} dstFilename if not present, destination filename will be equal to srcFilename
+ * @return {Promise} an image path
+ */
+function exportImage (storagePath, srcFilename, dstPath, dstFilename = '') {
+  dstFilename = dstFilename || srcFilename
+
+  const src = path.join(storagePath, 'images', srcFilename)
+
+  if (!path.extname(dstFilename)) {
+    dstFilename += path.extname(srcFilename)
+  }
+
+  const dstImagesFolder = path.join(dstPath, 'images')
+  const dst = path.join(dstImagesFolder, dstFilename)
+
+  return new Promise((resolve, reject) => {
+    if (!fs.existsSync(dstImagesFolder)) fs.mkdirSync(dstImagesFolder)
+
+    const input = fs.createReadStream(src)
+    const output = fs.createWriteStream(dst)
+
+    output.on('error', reject)
+    input.on('error', reject)
+    input.on('end', resolve)
+    input.pipe(output)
+  })
+}
+
+module.exports = exportImage