Ren'Py supports a self-voicing mode in which a speech synthesizer is used to read out text and other interface elements. This is intended to make Ren'Py games accessible to the vision impaired.
The Self-voicing mode can be toggled by pressing the v key.
When in self-voicing mode, keyboard navigation is changed so that the up and down arrow keys with iterate through all focusable displayables on the screen.
When a displayable is focused, Ren'Py will read the text associated with that displayable out loud. If no displayable is focused, Ren'Py will read on-screen text that cannot be focused. This will generally include dialogue and other text that comprises the game.
Ren'Py relies on the operating system to provide speech synthesis services. To adjust the speed of speech synthesis and the voice used, adjust your platform's speech settings.
Ren'Py's self-voicing works by extracting text from displayables and reading it to the player. Ren'Py extracts this text from two places.
Alternative text is supplied by a displayable's alt style property. It can also be supplied by actions supplied to buttons and values supplied to bars. Explicitly supplied alternative takes precedence over text supplied by actions or values, and both take precedence over text extracted from Text displayables.
Alternative text is translated using Ren'Py's string translation mechanism. Alternative text takes precedence over text extracted from a displayable and its children, but such child text is made available as the "[text]" string substitution. No other string substitutions are allowed.
Supplying the who_alt and what_alt parameters to Character sets the alt style property for the character name and body text, respectively. As an example, we define a Character that uses italics to indicate thoughts normally, but explicitly indicates thoughts via self voicing:
define thought = Character(None, what_italic=True, what_alt="I think, [text]")