How to activate Pinch-To-Zoom/Twisting with Synaptics Touchpad?

Holding down CTRL while pinching or zooming will allow you to perform the gesture.

@SpaceMonkeyPDX

Its not the real pinch to zoom gesture as expected. Its scrollUp + Ctrl zooms in ,scrollDown+Ctrl zooms out.

and because you have the Two-Finger-Scrolling enabled it seems like it but the right gesture is to scrollup and down with your two fingers while pressing ctrl button

I know it is a bit late but for others who may drop by

Type synclient to list all touchpad features then create a file to execute them at startup.

For example on 12.10 I am using these lines in my script:

synclient TapButton2=2
synclient TapButton3=3
synclient HorizEdgeScroll=1
synclient HorizTwoFingerScroll=1
synclient CircularScrolling=1
synclient PalmDetect=1

These enable Horizontal edge, two finger horizontal scroll, middle mouse button by tapping with two fingers and right mouse button by tapping with three fingers and palm detection to avoid unwanted clicks while typing...

But for pinch zoom. It seems there is nothing available at the moment.

I had success using Fusuma and xdotool. Install xdotool and the Fusuma gem and then create its config file at ~/.config/fusuma/config.yml and include the following:

pinch:
      2:
        in:
          command: 'xdotool key ctrl+plus'
          threshold: 0.15
        out:
          command: 'xdotool key ctrl+minus'
          threshold: 0.15

You may have to fiddle with the threshold and interval values until it responds to your liking.

Friends, I am on Ubuntu 21.04 now. And two-fingures-pinch-zoom works out of the box with Firefox. Real pinch zoom mac-style. Not just page scaling CTRL+[+], which makes responsive pages to change layout to mobile. But real useful zoom. which I use a lot when viewing images and sometimes paragraphs.