Fix PDF opening with external viewers

Author: zerox80

opencloudApp/src/main/java/eu/opencloud/android/extensions/ActivityExt.kt

@@ -33,6 +33,7 @@ import android.net.Uri
 import android.text.method.LinkMovementMethod
 import android.util.TypedValue
 import android.view.inputmethod.InputMethodManager
+import android.webkit.MimeTypeMap
 import android.widget.LinearLayout
 import android.widget.TextView
 import android.widget.Toast
@@ -164,8 +165,8 @@ private fun getIntentForSavedMimeType(data: Uri, type: String): Intent {
 private fun getIntentForGuessedMimeType(storagePath: String, type: String, data: Uri): Intent? {
     var intentForGuessedMimeType: Intent? = null
     if (storagePath.lastIndexOf('.') >= 0) {
-        val guessedMimeType = MimetypeIconUtil.getBestMimeTypeForOpen(type, storagePath)
-        if (guessedMimeType != type) {
+        val guessedMimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(storagePath.substring(storagePath.lastIndexOf('.') + 1))
+        if (guessedMimeType != null && guessedMimeType != type) {
             intentForGuessedMimeType = Intent(Intent.ACTION_VIEW)
             intentForGuessedMimeType.setDataAndType(data, guessedMimeType)
             intentForGuessedMimeType.flags = Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION