7.2 The class hierarchy for DUIM-Layouts
7.2.1 The <layout> class and its subclasses
The base class for the majority of DUIM layouts is the <layout> class, which is itself a subclass of <sheet>. All other layout-oriented classes are subclasses of <sheet>.
The immediate subclasses of <sheet> that are exposed by the DUIM-Layouts library are shown in Table 7.1. Only <basic-composite-pane>, <leaf-pane>, and <layout> have any subclasses defined. See Section 7.2.2 on page 451 for details of the subclasses of <layout>.
<sheet> | ||
<basic-composite-pane> | ||
<single-child-composite-pane> | ||
<multiple-child-composite-pane> | ||
<layout> | See Section 7.2.2 | |
<leaf-pane> | ||
<null-pane> | ||
<drawing-pane> | ||
<simple-pane> | ||
<top-level-sheet> |
All the actual layouts provided by the DUIM-Layouts library are subclasses of the base <layout> class, and are described in Section 7.2.2. In addition, a number of different types of pane are supplied by the DUIM-Layouts library.
<basic-composite-pane>- This is a basic type of pane that is used to create any sheet that can contain children. It has two subclasses, one used for sheets that take only a single child, and one for sheets that can take several children.
<drawing-pane>- This type of pane is used to create sheets on which geometric objects are drawn, for example, using the function provided by the DUIM-Geometry module or the DUIM-Graphics module. For more information on these modules, see Chapter 2, "DUIM-Geometry Library", and Chapter 6, "DUIM-Graphics Library", respectively.
<top-level-sheet>- This class is used for any sheets that are at the top level of the hierarchy of windows on the screen: that is, there is no other sheet that is the parent of an instance of
<top-level-sheet>. <leaf-pane>In contrast to
<top-level-sheet>, an instance of<leaf-pane>cannot have any children, and is at the end of the hierarchy of windows on the screen.<simple-pane>This class is the most basic type of pane, and is used when no other more suitable class is available.