App Name: Fits Viewer. Text viewer is a viewer that can read txt file and pdf file. Main function. 1. File manager. 2. Text viewer 2. 1 Changing the encoding. 2. 2 Adjusting Screen Brightness. 2. 3 Paging. 2. 4 Change font size. 2. 5 Change background color. 3. Pdf viewer 3. 1 Screen brightness adjustment.