UX improvements: keep user edits & do not reset cursor

Author: Stypox

app/src/main/java/org/schabi/newpipe/download/DownloadDialog.java

@@ -75,6 +75,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
+import java.util.Optional;
 
 import icepick.Icepick;
 import icepick.State;
@@ -566,19 +567,34 @@ public void onItemSelected(final AdapterView<?> parent,
     }
 
     private void onItemSelectedSetFileName() {
-        final String fileName = FilenameUtils.createFilename(getContext(),
-                currentInfo.getName());
-        switch (dialogBinding.videoAudioGroup.getCheckedRadioButtonId()) {
-            case R.id.audio_button:
-            case R.id.video_button:
-                dialogBinding.fileName.setText(fileName);
-                break;
-            case R.id.subtitle_button:
-                final String setSubtitleLanguageCode = subtitleStreamsAdapter
-                        .getItem(selectedSubtitleIndex).getLanguageTag();
-                dialogBinding.fileName.setText(getString(
-                        R.string.caption_file_name, fileName, setSubtitleLanguageCode));
-                break;
+        final String fileName = FilenameUtils.createFilename(getContext(), currentInfo.getName());
+        final String prevFileName = Optional.ofNullable(dialogBinding.fileName.getText())
+                .map(Object::toString)
+                .orElse("");
+
+        if (prevFileName.isEmpty()
+                || prevFileName.equals(fileName)
+                || prevFileName.startsWith(getString(R.string.caption_file_name, fileName, ""))) {
+            // only update the file name field if it was not edited by the user
+
+            switch (dialogBinding.videoAudioGroup.getCheckedRadioButtonId()) {
+                case R.id.audio_button:
+                case R.id.video_button:
+                    if (!prevFileName.equals(fileName)) {
+                        // since the user might have switched between audio and video, the correct
+                        // text might already be in place, so avoid resetting the cursor position
+                        dialogBinding.fileName.setText(fileName);
+                    }
+                    break;
+
+                case R.id.subtitle_button:
+                    final String setSubtitleLanguageCode = subtitleStreamsAdapter
+                            .getItem(selectedSubtitleIndex).getLanguageTag();
+                    // this will reset the cursor position, which is bad UX, but it can't be avoided
+                    dialogBinding.fileName.setText(getString(
+                            R.string.caption_file_name, fileName, setSubtitleLanguageCode));
+                    break;
+            }
         }
     }