Dynamically Toggle Between Colour Schemes in Existing Tabs and Windows Without Recompiling

[craigem]

I've been wondering about how to load the Solarized themes and switch between light and dark with a key stroke toggle.

This should be possible, but will require changing a few things.

You'll have to send a PR to add a hook that gets called right as Termonad is about to launch. Probably around here:

termonad/src/Termonad/App.hs

Lines 421 to 422 in db185e3

	widgetShowAll win
	widgetGrabFocus $ terminal ^. lensTerm

In your own config, you'll have to override that hook to define a new key binding for each existing terminal.

Here's an example of defining a key binding (this code defines the Alt-1, Alt-2, etc bindings for switching tabs):

https://github.com/cdepillabout/termonad/blob/db185e34a4b678183d8d1b1ce0be4c8bf3532fc8/src/Termonad/Keys.hs

termonad/src/Termonad/Term.hs

Lines 345 to 346 in db185e3

	void $ onWidgetKeyPressEvent vteTerm $ handleKeyPress mvarTMState
	void $ onWidgetKeyPressEvent scrolledWin $ handleKeyPress mvarTMState

Your key binding will have to call a function that loops through all the open tabs and sets the colors for the terminal.

Here's where that is currently being done:

termonad/src/Termonad/Config/Colour.hs

Lines 453 to 479 in db185e3

	-- | The default 'createTermHook' for 'colourExtCreateTermHook'. Set the colors
	-- for a terminal based on the given 'ColourConfig'.
	colourHook :: MVar (ColourConfig (Colour Double)) -> TMState -> Terminal -> IO ()
	colourHook mvarColourConf _ vteTerm = do
	colourConf <- readMVar mvarColourConf
	terminalSetColors vteTerm Nothing Nothing . Just
	=<< traverse toRGBA (paletteToList . palette $ colourConf)
	-- PR #28 / issue #29: Setting the background colour is broken in gi-vte or VTE. If
	-- this next line is called, then you are no longer able to set the
	-- background color using the palette.
	-- terminalSetColorBackground vteTerm =<< toRGBA (backgroundColour colourConf)
	terminalSetColorForeground vteTerm =<< toRGBA (foregroundColour colourConf)
	let optPerform setC cField = whenSet (cField colourConf) $ \c ->
	setC vteTerm . Just =<< toRGBA c
	optPerform terminalSetColorCursor cursorBgColour
	#ifdef VTE_VERSION_GEQ_0_44
	optPerform terminalSetColorCursorForeground cursorFgColour
	#endif
	where
	toRGBA :: Colour Double -> IO RGBA
	toRGBA colour = do
	let RGB red green blue = toSRGB colour
	rgba <- newZeroRGBA
	setRGBARed rgba red
	setRGBAGreen rgba green
	setRGBABlue rgba blue
	pure rgba

This is only setting colors for a single terminal, so you'll have to change it so it loops through all tabs.

Here's a function that loops through all tabs (although this is changing the font size):

termonad/src/Termonad/App.hs

Lines 192 to 199 in db185e3

	let terms =
	tmState ^..
	lensTMStateNotebook .
	lensTMNotebookTabs .
	traverse .
	lensTMNotebookTabTerm .
	lensTerm
	foldMap (\vteTerm -> terminalSetFont vteTerm (Just fontDesc)) terms

Originally posted by @cdepillabout in #94 (comment)

[craigem]

For the record, I am happy to work on this (probably as soon as next week), I just felt a new issue was appropriate as I felt we'd strayed from the original issue's remit, @cdepillabout

[cdepillabout]

@craigem Thanks for copying this issue over!

I'd definitely accept something like this if you wanted to take a shot at implementing it. Looking forward to the PR!