GOL Messages

To facilitate the processing of user actions on the objects, messaging are used. 

User passes messages from the input devices to GOL using the GOL message structure. The structure is described by the following table.

    typedef struct {
        BYTE         type;
        BYTE         uiEvent;
        int          param1;
        int          param2;
    } GOL_MSG;

GOLMsg() function accepts this structure and processes the message for all objects in the active list.

Messaging Flow

The messaging mechanism follows this flow:

1. User Interface Module (touch screen, keypad) sends a GOL message (the GOL_MSG structure).
2. A loop evaluates which object is affected by the message. This is done inside GOLMsg() function.
3. Affected object returns the translated message based on the GOL message parameters.
4. User can change default action with the callback function. If the call back function returns a non-zero value message will be processed by default.
5. Object should be redrawn to reflect new state.

Objects that are disabled will not accept any messages. GOLMsg() function must be called when GOL drawing is completed. In this case all objects have been drawn and it is safe to change objects states. GOLMsg() call can be done if GOLDraw() function returns non-zero or inside GOLDrawCallback() function.