tdevelop/doc/api/PropEditor.dox

/** \file PropEditor.dox
    \brief The TDevelop Property Editor library description page
*/

/** \page PropEditor TDevelop Property Editor library description

\section whatis What is Property Editor?

%Property editor is a collection of facilities to store and edit the
properties of an object. For example, look at %Qt Designer. Each widget
has a list of properties that can be edited in a nice table form.
Same ideology is used to edit properties in Kugar Report Designer
(from KOffice distribution). In TDevelop project manager can also display
the properties of currently selected build item in property editor.

\section over Library Overview

This PropertyEditor library is a redesign of Kugar property editing library 
with the goal to be more generic and extensible.

Library provides a @ref PropertyLib::Property class which stores property name, value and some
more important information like description or the list of possible values.
Using @ref PropertyLib::Property class adds more overhead over TQ_PROPERTY but provides more
flexibility. You can subclass @ref PropertyLib::Property and create your custom properties.
Custom properties can have either predefined type (see @ref PropertyLib::PropertyType) or
custom type. Custom type should be used if a custom property editor widget is
necessary.

Properties are organized into lists. @ref PropertyLib::PropertyList is designed
to store such lists in most efficient manner. It also allows to group
properties (for example think about "geometrical" properties like "x", "y", etc.).

Property lists can be displayed in @ref PropertyLib::PropertyEditor widget which will
display them in a table form. Note that @ref PropertyLib::PropertyEditor takes not
a @ref PropertyLib::PropertyList object, but @ref PropertyLib::PropertyAccessor instead.

@ref PropertyLib::PropertyAccessor is designed to provide a method to access an intersection
of property lists. For example, let's consider object A with property list a_list
abd object B with list b_list. Now let's imagine we want to display common properties
from a_list and b_list in one @ref PropertyLib::PropertyEditor widget. Obviously, we need to
"intersect" a_list with b_list and display the result of intersection.
This is why @ref PropertyLib::PropertyAccessor is used for editing. If we change
the value of a property in the editor, @ref PropertyLib::PropertyAccessor will update
both properties from underlying a_list and b_list.

@ref PropertyLib::PropertyEditor at the same time shows only one editor for selected
property in the list. Each @ref PropertyLib::PropertyType has corresponding @ref PropertyLib::PropertyWidget
which displays property editor or draws a property in the list if it is not edited.
More exactly, if @ref PropertyLib::PropertyEditor needs to display editor widget, it displays
@ref PropertyLib::PropertyWidget, else it calls @ref PropertyLib::PropertyWidget::drawViewer function.
Custom property widgets should be subclasses of @ref PropertyLib::PropertyWidget.

To create property widgets at runtime, a factory is used. Factory class is
called @ref PropertyLib::PropertyMachineFactory. Static function @ref PropertyLib::PropertyMachineFactory::getInstance
can be used to obtain the reference to the factory instance. Factory creates and returns
so-called @ref Machine for each registered property type (either predefined or user defined).

@ref Machine contains @ref PropertyLib::PropertyWidget and a list of "detailed" machines.
Usually only property widget is necessary for a property but there are 
complex properties like "Font" for example. We would like to see separate editors
for font family, size, etc. and a button to choose all of these in the dialog.
For that "Font" property, a PropertyWidget with a "choose font" button 
and also number of detailed widgets like "font family" combo, etc. can be created.

\section Examples
A simple example on how to create a property editor and use it with one property list:
\code
    PropertyEditor *m_editor = new PropertyEditor(this);
    
    PropertyList *list = new PropertyList;
    list->addProperty("My Group", new Property(Integer, "First Property",
        "This is my first property", -5));
    list->addProperty("My Group", new Property(String, "Second Property",
        "This is my second property", "Hello"));
    list->addProperty(new Property(Color, "Third Property",
        "This is my third property", QColor("green")));
        
    m_editor->populateProperties(*list);
\endcode

More advanced example with property accessors and list intersection:
\code
    PropertyEditor *m_editor = new PropertyEditor(this);
    
    PropertyList *list = new PropertyList;
    list->addProperty("My Group", new Property(Integer, "First Property",
        "This is my first property", -5));
    list->addProperty("My Group", new Property(String, "Second Property",
        "This is my second property", "Hello"));
    list->addProperty(new Property(Color, "Third Property",
        "This is my third property", QColor("green")));

    PropertyList *list2 = new PropertyList;
    list2->addProperty("My Group", new Property(Integer, "First Property",
        "This is my first property", -7));
    list2->addProperty("My Group", new Property(String, "Second Property",
        "This is my second property", "Hello"));
    list2->addProperty(new Property(String, "Third Property",
        "This is my third property", "green"));

    PropertyAccessor *ac = list->intersect(*list2);
    
    m_editor->populateProperties(ac);
\endcode
In this example only properties named "First Property" and "Second Property" will be shown in editor.
"Third Property" has different types in list and list2 and will not be included in intersection. 

*/