Flow: Add native API for triggering a flow action

[fietser28]

In native code I would like to have an API to change to trigger a specific flow action.
It should be clear if this API is thread safe with respect to the ui_tick() call or not.

This is similar to #314 but for actions instead of screens. API with enum of actions and a eez_flow_trigger_action(action_enum) call seems like an ok interface to me.

[mvladic]

With this API we should also support:

• sending input values
• receiving output values.
• to know when action is finished

So, one possible way is the following API:

void eez_flow_trigger_action(ActionsEnum actionId, eez::Value *inputs, eez::Value *outputs, void (*on_finished)(const char *error));

Studio should generate for each flow action two more enum's, for example something like this:

enum ActionFooInputs {
   ACTION_FOO_INPUT_INPUT1 = 0,
   ACTION_FOO_INPUT_INPUT2 = 1,
  ...
};

enum ActionFooOutputs {
   ACTION_FOO_INPUT_OUTPUT1 = 0,
   ACTION_FOO_INPUT_OUTPUT2 = 1,
  ...
};

Only drawback is that using eez::Value requires C++.

[mvladic]

Only drawback is that using eez::Value requires C++.

We can create a C wrapper for eez::Value. For example:

CValue *CValue_createInteger(int value);
CValue *CValue_createString(const char *value);
int CValue_getInteger(CValue *cv);
char *CValue_getString(CValue *cv);
void CValue_delete(CValue *cv)

Then API decl would be:

void eez_flow_trigger_action(ActionsEnum actionId, CValue *inputs, CValue *outputs, void (*on_finished)(const char *error));