gui-cs.Terminal.Gui/docfx/includes/view-composition.md

View Composition Diagram

classDiagram
    class View {
        +Frame: Rectangle
        +Margin: Adornment - outermost
        +Border: Adornment - border lines and Title
        +Padding: Adornment - innermost - Scrollbars
        +Viewport: Rectangle describing portal into ContentArea
        +ContentArea: Rectangle with Location always 0,0
        +GetContentSize(): Size
        +SetContentSize(Size)
    }

    class Adornment {
        +Thickness: Thickness
    }

    class Thickness {
        +Top: int
        +Right: int
        +Bottom: int
        +Left: int
    }

    class Rectangle {
        +Location: Point
        +Size: Size
    }

    View --> Adornment : has
    Adornment --> Thickness : has
    View --> Rectangle : has

    note for View "Frame defines location and size relative to SuperView"
    note for Adornment "Separates Frame from Viewport"
    note for Rectangle "Defines location and size"

The diagram above shows the structure of a View's composition:

1. Frame: The outermost rectangle defining the View's location and size
2. Margin: Separates the View from other SubViews
3. Border: Contains visual border and title
4. Padding: Offsets the Viewport from the Border
5. Viewport: The visible portion of the Content Area
6. Content Area: Where the View's content is drawn (shown larger than Viewport to illustrate scrolling)

Each layer is defined by a Thickness that specifies the width of each side (top, right, bottom, left). The Content Area is shown as a separate container that the Viewport "looks into" - this illustrates how scrolling works. In this example, the Viewport is positioned at (5,5) relative to the Content Area, showing how scrolling works.