Zoom with mouse-button + scroll wheel?

Question

I'd like to enable changing the font size by holding down the right mouse button and using the scroll-wheel. Emacs does however treat mouse buttons as keys, so this obviously cannot be achieved directly by a straight-forward (define-key ... (kbd ...) ...) binding.

Since I also don't want to disable the standard actions performed by "click and release" of the right mouse button, I can't just bind something to <up/down-mouse-3>. Instead, I'd like to bind a command to the scroll events <mouse-4> and <mouse-5>, that detects, whether the right mouse button is being held.

Is this possible?

Related questions point to the variable track-mouse, but it doesn't seem, like that method can distinguish different mouse buttons.

Answer 1

Library zoom-frm.el lets you do either of these things using the mouse wheel:

• Zoom the buffer text size, for all windows showing a given buffer. This is called text-scaling.
• Zoom the frame text size, for a given frame or for all frames.

It, in turn, requires these libraries:

• frame-cmds.el
• frame-fns.el

See also Changing Font Size.

These are bindings recommended in zoom-frm.el for the mouse wheel:

(global-set-key (vector (list 'control mouse-wheel-down-event))
                'zoom-in)
(global-set-key (vector (list 'control 'meta mouse-wheel-down-event))
                'zoom-all-frames-in)
(global-set-key (vector (list 'control  mouse-wheel-up-event))
                'zoom-out)
(global-set-key (vector (list 'control 'meta mouse-wheel-up-event))
                'zoom-all-frames-out)

Perhaps you can provide similar bindings for simultaneous use of the wheel and holding mouse-3 (right button) pressed. I don't know, and I'm not really motivated to find out. Perhaps someone else here will help with that.

---

For buffer (not frame) zooming, you might also want to use library face-remap+.el. It lets buffer resizing also zoom the window size accordingly (horizontally, vertically, or both). That way, you can take advantage of the space freed up by resizing (text-scaling) to a smaller font.

Answer 2

mapping behavior similar to browser might be helpful,

• zoom in : Ctrl + mouse-scroll-up and Ctrl + Shift + =
• zoom out : Ctrl + mouse-scroll-down and Ctrl + -
• zoom 1x : Ctrl + 0

these config are for the single buffer

(global-set-key [C-mouse-4] 'text-scale-increase)
(global-set-key [(control ?+)] 'text-scale-increase)
(global-set-key [C-mouse-5] 'text-scale-decrease)
(global-set-key [(control ?-)] 'text-scale-decrease)
(global-set-key (kbd "C-0") '(lambda () (interactive)
                               (text-scale-adjust
                                (- text-scale-mode-amount))
                               (text-scale-mode -1)))