Create class diagrams

You can create UML-style models that contain class diagrams. They show classes, dependencies, inheritance, associations, aggregation, and composition to visualize a system in an object-oriented way.

{Class diagram in the model editor}

A class diagram in the model editor.

To create class diagrams:

  1. To add C++ classes to class diagrams, drag files from Projects to the editor, and select Add Class.
  2. In addition to the common element properties, you can specify the following properties:
    • In the Template field, specify the template to use.
    • In the Template display field, select the display format for the template:
      • Smart displays the template as Box or Angle brackets, depending on the class properties.
      • Box displays the template in a small box with a dotted border in the top right corner of the class icon.
      • Angle brackets writes the template in angle brackets behind the class name using the C++ syntax.
    • In the Members field, specify members for the class, as described in Specify members.
    • Select Clean Up to format the contents of the Members field depending on their visibility (private, protected, public) and following the rules set for whitespace, line breaks, and so on.
    • Select the Show members check box to show the members in the diagram.

To navigate from a class in a diagram to the source code, double-click the class in the editor or select Show Definition in the context menu.

Add relations

Elements in class diagrams can have the following types of relations: inheritance, association, and dependency. The end points of association relations can have the following properties: role, cardinality, navigable, and relationship.

To create self-relations, start creating a new association and press Shift to create a new sampling point while dragging the association. Create another sampling point and drag the association to the same class.

To add more points, press Shift and click a relation. To delete a point, press Ctrl and click a point.

Specify members

To specify members for the class, enter each member on a separate line using a C++ like syntax. For example, the following lines define the method m that is private, virtual, and constant:

virtual int m(string a) const;

You may group members:

QPointF position;
QSizeF size;

You may add stereotypes to members:

<<setter>> setPosition(const QPointF &pos);

There are some limitations of the parser:

  • Multi-line declarations work only if lines are wrapped within nested brackets:
    void setSize(int width,
                 int height);
  • Preprocessor macros will not be translated. Some Qt keywords are recognized (for example Q_SLOT).
  • Function pointer declarations are interpreted as methods.
  • throw() and noexpect() specifiers are not ignored but will make the declaration a method.

See also Create component diagrams, Create package diagrams, Create UML-style models, and Model Editor.

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