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eez-open / studio

Cross-platform low-code GUI and automation
https://www.envox.eu/studio/studio-introduction/
GNU General Public License v3.0
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[LVGL] Triggering drop down list event when changing the selected value from a flow node #614

Closed ajayre closed 2 weeks ago

ajayre commented 2 weeks ago

LVGL 9.1

I have a drop down list called Foo The Selected field of Foo is set to assignable with the global native variable name FooValue Foo has a VALUE_CHANGED flow event that enables or disables some UI elements depending on if FooValue is 0 or 1 On another page I have a switch. If the switch is checked then it sets FooValue to 0

When I run this and turn the switch on the drop down list Foo changes to item 0 as expected. However that doesn't seem to trigger the VALUE_CHANGED event which I need to keep the UI consistent.

How do I get the event working?

Thanks!

ajayre commented 2 weeks ago

OK, I solved this by adding a SCREEN_LOADED event and in that event I re-evalulate FooValue to force an update of the enabled/disabled items.

But shouldn't setting a variable connected to the Selected property of a drop down list always trigger the VALUE_CHANGED event?

mvladic commented 2 weeks ago

This depends on LVGL because LVGL is one who sends VALUE_CHANGED events. When variable is changed with SetVariable, Studio generated code will call lv_dropdown_set_selected and this function doesn't send VALUE_CHANGED event.

Hint: You can use Watch action to detect that some variable has been changed and do the stuff.