[Feature Request] Multi Touch Support

[scottyseng]

Validations

• I have checked for similar feature requests and could not find any.
• I have made sure this is not an already-existing feature.

Description

Give multi touch support for panning, zooming, and rotating the canvas.

Also have an option to ignore touch input for tools if it is a single finger. CSP does this and it does great at preventing accidental lines because of a single finger triggering the pen tool as an example.

Use Case: Cintiq Pro has multi touch support and it is great for moving the canvas around

Suggested solution

Doing some testing for Playmer and confirmed SDL works at tracking input.

Alternative solution

No response

Additional Context

No response

[r888800009]

This PR provides moving and scaling features, but the parameters still need to be corrected

• Experimental: Support touchpad  #399