[Interest] Button is being latched sometimes in Qt 5.6.3

Ramakanth Kesireddy rama.kesi at gmail.com
Thu Nov 19 07:32:11 CET 2020


Hi,

Further details of the issue are mentioned below:
Issue: Button’s on the UI QT 5.6.3 widgets application seem to be stuck
sometimes when we press and release and found that mousereleaseevent is not
received.

Also Qt 5.6.3 on target is configured with -tslib and there are penup
events received(like sample.pressure=0), not sure if the release event is
missed to propagate to the
widget with missing coordinates.

Below is the sample output from the tslib_test program which shows a
negative x coordinate value with the pressure value 0 at times. Is it
possible that  Qttslib(qtbase/src/platformsupport/input/tslib/qtslib.cpp) would
throw out that sample which would result in the missed mouseReleaseEvent?


                      XPos   YPos   Pressure
                      316    216    234
                      316    216    232
                      318    214      0
                      330     22    195
                      330     21    196
                      329     22      0
                      228    223    168
                      228    223    168
                      227    221      0
                      229    217    173
                      231    215      0
                      248    210    160
                      248    210    160
                      254    209      0
                      267    369    252
                      263    372      0
                      441    338    275
                      442    336    274
                      439    339      0
                      499    331    292
                      499    330    291
                      496    328      0
                      374    367    269
                      374    367    267
                      376    371      0
                      561    199    280
                      561    199    280
                      558    201      0
                      547    329    311
                      547    329    309
                      544    329      0
                      494    382    300
                      495    381    300
                      498    378      0
                      568    118    264
                      569    119    263
                      570    121      0
                       48    101    175
                       48    101    173
                       47    101      0
                      141    182    201
                      141    183    200
                      140    184      0
                      534    267    285
                      533    266    285
                      531    265      0
                      403    387    280
                      404    388    280
                      409    390      0
                      288    407    253
                      288    407    251
                      289    409      0
                      318    345    253
                      319    345    253
                      320    345      0
                      311    290    257
                      309    298    278
                      304    297      0
                      423    236    238
                      424    234      0
                      422    234    259
                      416    236      0
                      285    300    245
                      283    299      0
                      333    304    251
                      324    289    248
                      325    289      0
                      383    289    258
                      381    296      0
                      417    292    267
                      417    274    265
                      413    277    263
                      405    285      0
                      407    283    268
                      407    283    266
                     -122    295      0
                      88     24    172
                      89     25    171
                      86     33      0
                      392    316    270
                      393    319    270
                      391    325      0
                      -44    214    246
                      -44    214      0
                      140    306    264
                      140    306    264
                      146    315      0
                      118    293    282
                      118    293    281
                      129    294      0
                      -25    180    254
                     -25    180      0
                      106    280    234
                      108    285      0
                      318    289    314
                      319    289    314
                      352    281      0
                      160    302    167
                      157    296    278
                      166    302      0
                      -19    199    259
                      -19    199      0
                      116    305    261
                      236    296    287
                      237    299      0
                     -122    295    263
                     -122    295      0
                       21    453    254
                       21    453    253
                       22    452      0
                       26     70    177
                       26     71    175
                       27     70      0
                      312    272    247
                      312    272    247
                      570    428      0
                      558    416    307
                      558    416    307
                      608    438      0

Here is the code in qtslib.cpp based out of Qt5.6.3:
// work around missing coordinates on mouse release
        if (sample.pressure == 0 && sample.x == 0 && sample.y == 0) {
            x = m_x;
            y = m_y;
        }

Could you please let me know if there is any known issue of missing mouse
release events in Qt 5.6.3 or any known patch available with qtslib in
Qt5.6.3
or let me know if it would work ignoring the condition sample.x==0 &&
sample.y==0?

Appreciate your feedback in this regard.

Best Regards,
Ramakanth

On Sun, Nov 15, 2020 at 12:55 PM Ramakanth Kesireddy <rama.kesi at gmail.com>
wrote:

> Hi,
>
> Observed that button(custom QPushButton) is being latched sometimes or
> stucks at the pressed state and mouseReleaseEvent event is not generated at
> all.
>
> The target platform uses Qt v5.6.3 via LinuxFB where FB_DA8XX driver
>  is replaced by LCDC driver in the v4.14 linux kernel built with yocto
> rocko.
>
> Based on tests, we found that legacy fb devices are being able to be used
> with Qt v5.6.3 via LinuxFB, such as the one created by the LCDC driver.
>
> Appreciate any suggestions if such behavior is observed specific to Qt
> 5.6.3 or any feedback why it could occur at times?
>
> Best Regards,
> Ramakanth
>
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