PControl

This is an abstract base class for any control element Classes.
Note: most objects don't update themselves when modified. Use the refresh() method to redraw the control. This could have been done automatically, but for speed reasons, it was not (imagine a listbox with some 100 elements).

Synopsis

#include <PLUI.h>

Derivation

PBaseObj

PControl

PList

PField

PScrollbar

Constructors

You cannot construct any instances of this class, but the minimal constructor is

    PControl(PForm* parent, Word id);

to create a control with a parent form from a resource id.
or

    PControl(PForm* parent, VoidPtr objPtr);

to create a control from an object pointer returned by the system. This is intented to be used internally.

Public functions

    virtual PControl& refresh() = 0;

Redraws the control. This functions must be implemented by any derived class.

    virtual Boolean usable()  = 0;
    virtual Boolean enabled() = 0;
    virtual Boolean visible() = 0;

Return the status attributes for the control. Theses functions must be implemented by any derived class.

    virtual PControl& show(Boolean show);
    virtual PControl& show();
    virtual PControl& hide();

Set the visibility of the object. This calls FrmShowObject if your control does not respond to this, you must override these methods.

    virtual PControl& usable(Boolean f);
    virtual PControl& enable(Boolean f);

Set the attributes of a control. Does not have an effect on all controls.

    SWord idx();

Returns the object's index in the form if the parent form is already shown, otherwise it returns -1. This can be used to access PalmOS APIs that need the object's index and are not implemented yet.

Protected functions

    virtual void loadInit();
    virtual void unloadExit();

These methods are called when the parent form has been loaded into memory or is going to be closed. The default is, to do nothing. Any initialization that can only be done when a form is loaded should be done in loadInit(). This can e.g. be setting a text that has been stored in a constructor.
Freeing allocated memory that's not need when the form is closed, and similar tasks should be done in unloadExit().
Note: unloadExit is only called when the application is closed (switch to another application) or if a PForm::goTo() is issued. In particular it is not called when a form, which was opened using PForm::popUp() issues a PForm::returnTo()

    VoidPtr objPtr();
    FormPtr frmPtr();

Return a VoidPtr to the controls structure or a FormPtr to the parent if the parent form is already shown, otherwise they return 0. These can be used to access PalmOS APIs.