Layout Windows

Layout windows are encapsulated in the class TLayoutWindow, which is derived from TWindow.

Along with TFrameWindow, TLayoutWindow provides the basis for decorated frame windows and their ability to arrange decorations in the frame area.

Layout windows are so named because they can lay out child windows in the layout window's client area. The children's locations are determined relative to the layout window or another child window (known as a sibling). The location of a child window depends on that window's layout metrics, which consist of a number of rules that describe the window's X and Y coordinates, its height, and its width. These rules are usually based on a sibling window's coordinates and, ultimately, on the size and arrangement of the layout window.

Layout metrics for a child window are contained in a class called TLayoutMetrics. A layout metrics object consists of a number of layout constraints. Each layout constraint describes a rule for finding a particular dimension, such as the X coordinate or the width of the window. It takes four layout constraints to fully describe a layout metrics object. Layout constraints are contained in a structure named TLayoutConstraint, but you usually use one of the TLayoutConstraint-derived classes, such as TEdgeConstraint, TEdgeOrWidthConstraint, or TEdgeOrHeightConstraint.

See Also

• Layout Constraints
• Defining Constraining Relationships
• Defining Constraints
• Using Layout Windows