Chapter 1

� The general-purpose control designed to live in a dialog should show the cursor, if it
has one, when focused, and not otherwise. Many editors include some kind of cursor, or
even the window server's flashing text cursor to indicate that they have focus.
12.2.6 Dimming and Visibility
There are two ways to indicate that a control in a dialog cannot receive focus:
� Make it invisible: You can make the entire line – prompt and control – invisible. The
control environment has full support for this action; invisible controls are omitted from
redraw and pointer handling, and dialogs will not allow invisible lines to be given focus.
� Dim it : If you dim a control, it will be omitted from pointer handling. Dialogs will not
allow a dimmed line to gain focus. However, the control environment will not omit a
dimmed control from redrawing; rather, the implementer of the control has to code
Draw() to dim the control explicitly.
The good thing, supposedly, about dimming is that the user can still see the control and the
value it contains, even though they can't change it. But actually, dimming is a nuisance; the
writer of the control has to add support in Draw() (using logical colors can help with this –
see Chapter 15 for more information). In any case, unavailable options might be entirely
meaningless, in which case you don't want to dim the control, you want to hide it altogether.
Some dialogs in UIQ use a cute compromise; when you call Make-
LineVisible(EFalse), the dialog dims the prompt and makes the general-purpose
control invisible. The user gets the right effect, the general-purpose control doesn't have to
support dimming explicitly, and there's no attempt to display meaningless values.
The relevant functions for dimming are found in CCoeControl:
class CCoeControl : public CBase
{
public:
...
IMPORT_C virtual void SetDimmed(TBool aDimmed);
IMPORT_C TBool IsDimmed() const;
...
};
If you need to, honor IsDimmed() in your Draw() function.
12.2.7 Valiation
While a control has focus and the user is editing it, it may become temporarily invalid –
numeric editors are an example of this. However, when focus is taken from a control – for a
change in dialog line, or because Done was pressed – it's important that the control should
be valid.
UIQ calls PrepareForFocusLossL() on any control from which it is about to remove
focus. The default CCoeControl implementation of this function is empty: there is no need
to override it for a control whose internal state can never be invalid (for example, a choice
list, a button, a checkbox, or a text editor). If your control could be invalid, however, you
should implement this function to check the current validity of the control. If it is invalid, you
should: