Sumatrapdf: Please add smooth touchpad support

[vvRFvv]

I have a Thinkpad with a synaptics touchpad and the newest version of windows. It would be nice to have smooth touchpad scrolling and zooming (not in steps) as it is already possible when using the touchscreen and sumatra.

[kjk]

I don't know what "smooth scrolling and zooming" means in this context.

Zooming will always happen in steps because it's very expensive operation.

Scrolling already happens in small increments (assuming contiguous layout), which should be true for mouse, touchpad and any other device that generates scroll events.

[vvRFvv]

Please take a look at the video. First I use the touchscreen to scroll and zoom, then the trackpad. Especially the zooming with the trackpad has huge steps.

sumatraScrolling.zip

[myphs]

Yes, this already works, but Sumatra is ignoring the input.
You also already can scroll smoothly when you hold the right mouse button and move the mouse, but then you are forced to release the RMB and move to another place to scroll again. On a laptop this is very unconvenient.
When using precision touchpad the two finger scroll should be smooth as well then.
I would very appreciate if this feature could be implemented.

[GitHubRulesOK]

SumatraPDF is not ignoring any scroll input it is respecting the inputs from Windows telling it to move # lines of text

Touchpad or mouse scrolling (much the same as font sizes) is tied to the OS (Windows settings) there is no 0.01 line granularity it is simply # of lines in a step range of 1 to 99 (or page by page)
Please write to Bill G and his team to change that.

SumatraPDF uses an engine that is similar in reaction to similar document apps (check out your word Pad etc. and yes large programming teams can bypass that limitation in most paid for applications)

The next best option is Auto scroll drivers which are common on the middle button of a mouse but not always found on touchpads Please write to Synaptics or others to add that option if it is missing.

The third option is coasting not usually found on mice but may be offered on some touchpads however it is normally tied to the default number of full lines as above.

Finally, we have the fall back of smooth grab'n'drag as described by Myphs Which, if you have enabled vertical scrolling on your touchpad, can be achieved within the hardware limits by holding down the right button and sliding a finger up and down the slider zone.

Zooming is a different matter, as stated above SumatraPDF uses zoom steps (again similar to many other apps) you can edit the settings file to change the step percentages between 8.33 and 6400.

ZoomLevels = 8.33 12.5 18 25 33.33 50 66.67 75 100 125 150 200 300 400 600 800 1000 1200 1600 2000 2400 3200 4800 6400
ZoomIncrement = 0