TIP 570: Gesture Support for Finger Scrolling and "Pinch to Zoom"

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Bounty program for improvements to Tcl and certain Tcl packages.
Author:         Harald Oehlmann <[email protected]>
State:          Draft
Type:           Project
Vote:           Done
Created:        18-Mar-2020
Post-History:
Keywords:       Tk, bindings
Tcl-Version:    8.7

Abstract

Support for the gestures "finger scroll" and "pinch to zoom" are proposed in a platform neutral way.

NB: This tip is not ready specified yet. Anybody is invited to contribute.

Specification

Overview

Many systems (e.g. Windows, Linux Window Manager, Mac-OS, Android) nowdays support gestures in a generic manner. The gestures may be different and the input media may be different. Possible input media are a touch-screen or a touchpad.

The aim of this TIP is to make gestures provided by the system available within Tk.

The targeted gestures are:

There is a direct relation to the displayed image if a touch-screen is used. The scroll gesture gives a source and target point on the screen.

Platforms

The following discussion is about possible implementations on different platforms

Windows

Peter Spjuth has authored a Windows implementation in tk.branch pspjuth-touch

The two gestures are implemented by the following virtual bind tags:

AndroWish

Christian Werner has defined the following virtual binding tags. This information is copied and adapted from the Androwish documentation.

Linux

Mac-OS

Rationale

Implementation

The following fragments are known:

Discussion

Copyright

This document has been placed in the public domain.