From 16e8aca7141199dd67ee619daf7af991591909ee Mon Sep 17 00:00:00 2001
From: mroxso <24775431+mroxso@users.noreply.github.com>
Date: Thu, 20 Mar 2025 17:14:06 +0100
Subject: [PATCH] rm exif data from images before uploading (#55)

---
 components/UploadComponent.tsx | 88 +++++++++++++++++++++++++++++-----
 1 file changed, 76 insertions(+), 12 deletions(-)

diff --git a/components/UploadComponent.tsx b/components/UploadComponent.tsx
index 653e84b..cfdf57b 100644
--- a/components/UploadComponent.tsx
+++ b/components/UploadComponent.tsx
@@ -48,6 +48,57 @@ async function calculateBlurhash(file: File): Promise<string> {
   })
 }
 
+/**
+ * Removes EXIF metadata from an image by redrawing it on a canvas
+ * @param file The image file to process
+ * @returns A Promise that resolves to a new File object without EXIF data
+ */
+async function removeExifData(file: File): Promise<File> {
+  return new Promise((resolve, reject) => {
+    // Only process images
+    if (!file.type.startsWith("image/")) {
+      resolve(file)
+      return
+    }
+
+    const img = new Image()
+    img.onload = () => {
+      // Create a canvas with the same dimensions as the image
+      const canvas = document.createElement("canvas")
+      canvas.width = img.width
+      canvas.height = img.height
+
+      // Draw the image to the canvas, which strips EXIF data
+      const ctx = canvas.getContext("2d")
+      if (!ctx) {
+        reject(new Error("Could not get canvas context"))
+        return
+      }
+      
+      ctx.drawImage(img, 0, 0)
+
+      // Convert canvas to blob with the same type as the original file
+      canvas.toBlob((blob) => {
+        if (!blob) {
+          reject(new Error("Could not create blob from canvas"))
+          return
+        }
+        
+        // Create a new File object with the same name and type
+        const sanitizedFile = new File([blob], file.name, { 
+          type: file.type,
+          lastModified: file.lastModified
+        })
+        
+        resolve(sanitizedFile)
+      }, file.type)
+    }
+
+    img.onerror = () => reject(new Error("Failed to load image"))
+    img.src = URL.createObjectURL(file)
+  })
+}
+
 const UploadComponent: React.FC = () => {
   const { publish } = useNostr()
   const { createHash } = require("crypto")
@@ -102,15 +153,16 @@ const UploadComponent: React.FC = () => {
     setShouldFetch(true)
   }, [])
 
-  const handleFileChange = (event: ChangeEvent<HTMLInputElement>) => {
+  const handleFileChange = async (event: ChangeEvent<HTMLInputElement>) => {
     const file = event.target.files?.[0]
     if (file) {
+      // Create a clean URL for preview that will be revoked later
       const url = URL.createObjectURL(file)
       if (url.startsWith("blob:")) {
         setPreviewUrl(url)
       }
 
-      // Optional: Bereinigung alter URLs
+      // Optional: Cleanup old URLs
       return () => URL.revokeObjectURL(url)
     }
   }
@@ -125,7 +177,7 @@ const UploadComponent: React.FC = () => {
 
     const formData = new FormData(event.currentTarget)
     const desc = formData.get("description") as string
-    const file = formData.get("file") as File
+    let file = formData.get("file") as File
     let sha256 = ""
     let finalNoteContent = desc
     let finalFileUrl = ""
@@ -145,16 +197,27 @@ const UploadComponent: React.FC = () => {
 
     // If file is present, upload it to the media server
     if (file) {
-      const readFileAsArrayBuffer = (file: File): Promise<ArrayBuffer> => {
-        return new Promise((resolve, reject) => {
-          const reader = new FileReader()
-          reader.onload = () => resolve(reader.result as ArrayBuffer)
-          reader.onerror = () => reject(reader.error)
-          reader.readAsArrayBuffer(file)
-        })
-      }
-
       try {
+        // Remove EXIF data from image if it's an image file
+        if (file.type.startsWith("image/")) {
+          try {
+            file = await removeExifData(file)
+            console.log("EXIF data removed from image")
+          } catch (error) {
+            console.error("Error removing EXIF data:", error)
+            // Continue with original file if EXIF removal fails
+          }
+        }
+
+        const readFileAsArrayBuffer = (file: File): Promise<ArrayBuffer> => {
+          return new Promise((resolve, reject) => {
+            const reader = new FileReader()
+            reader.onload = () => resolve(reader.result as ArrayBuffer)
+            reader.onerror = () => reject(reader.error)
+            reader.readAsArrayBuffer(file)
+          })
+        }
+
         const arrayBuffer = await readFileAsArrayBuffer(file)
         const hashBuffer = createHash("sha256").update(Buffer.from(arrayBuffer)).digest()
         sha256 = hashBuffer.toString("hex")
@@ -256,6 +319,7 @@ const UploadComponent: React.FC = () => {
               console.log("final Event: ")
               console.log(signedEvent)
               publish(signedEvent)
+              // alert("OK:" + signedEvent)
             }
 
             setIsLoading(false)