Re: Stylus drawing input?

[Po Lu]

Emacs 29 already has native support for version 2 of the the X Input extension 
and its various input devices.

See the node Touchscreen Events in the Emacs Lisp reference manual.  This is 
not yet supported on the PGTK build.

On January 24, 2023 5:15:58 AM GMT+08:00, Dov Grobgeld <dov.grobgeld@gmail.com> 
wrote:
>On X11, to read stylus input, we need to use XInput extension.
>
>Gdk, used in gtk, has a good abstraction to it that allows doing code
>like the following to distinguish between mouse and stylus input in
>its motion notify callback, and in this case extract the pressure.
>
>  int on_motion_notify_event(GdkEventMotion *event)
>  {
>    // The pressure value is:
>    //   found=false for mouse motion
>    //   0 for proximity stylus motion
>    //   >0 for the pen touching the pad
>    double pressure=-1;
>    int found = gdk_event_get_axis((GdkEvent*)event,
>GDK_AXIS_PRESSURE, &pressure);
>    GdkDeviceTool *tool = gdk_event_get_device_tool((GdkEvent*)event);
>
>    // For mouse the tool isn't defined, so we set a default -1
>    GdkDeviceToolType tool_type = (GdkDeviceToolType)(-1);
>    if (tool)
>      // true for stylus only
>      tool_type = gdk_device_tool_get_tool_type (tool);
>
>    printf("motion_notify: tool_type=%d,
>x=%.3f},y=%.3f},found_stylus=%d,pressure=%.3f\n",
>          (int)tool_type,
>          event->x, event->y, found, pressure);
>    return TRUE;
>  }
>
>To support styluses (i.e. to distinguish them from mouse events) we
>need something similar in emacs.
>
>Regards,
>
>
>On Mon, Jan 16, 2023 at 10:27 AM <tomas@tuxteam.de> wrote:
>>
>> On Mon, Jan 16, 2023 at 08:45:55AM +0100, Dr. Arne Babenhauserheide wrote:
>> > PS: Here is a website with a description that does not rely on unfree
>> >     platforms: https://misohena.jp/blog/2021-09-21-emacs-easy-draw.html
>> >
>> > The clearest description is a gif, though:
>> > https://misohena.jp/blog/wp-content/uploads/2021-09-21-edraw-example.gif
>>
>> Thanks for the non-github link!
>>
>> Cheers
>> --
>> t
>