Volito and other low-end tablet workaround with MyPaint

I meet since long time a precision bug with my Wacom low-end Volito tablet and MyPaint. This tablet has got a very low precision: 512 level of pressure and then a very low approximation. The Linuxwacom driver send not-null values when stylus come near from tablet surface. This is probably linked to the low precision of this cheap tablet. The information ‘button 1 down’ is correctly only send when the stylus really touch the tablet with little pressure.

The Bolito2 and Bamboo are probably also affected by this behavior, if it’s the case, write a comment here please and thee effect of the workaround. If you see this behavior with xidump (included generally in Wacomtool package) write me a line.

xidump 'Wacom Volito'

to run it in my case.

As Mypaint fondamentally start to stroke as soon as pressure information is given, even if button down event is not sent, this cause to me some headhaches with residual strokes in my drawings. This bug (and following workaround) is also present for the great historic color (button 2) feature of actual SVN version of MyPaint.

The workaround as given by MyPaint author is to modify slightly the main pressure curve of MyPaint.

(Menu Edit=>Settings in pressure tab, shift slightly the left-bottom black square of the curve to the right, then press Save button (Warning, with high value, MyPaint v0.6.0 crash with some tools).

I managed to do another workaround of this bug by using a really low value in the configuration file created after the saving:

~/.mypaint/settings.conf

Thes values give good results:

global_pressure_mapping = [(0.0, 1.0), (0.011, 1.0), (1.0, 0.0)]

(0.011,1.0) values are rounded value after graphicaly playing with curve. I’m not sure exacly but value above about 1.5 or 2.0 (for x) crashed Mypaint with INK tool and pressure at max

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