Namespace Terminal.Gui.ViewBase

The ViewBase namespace contains the foundational view system and core UI building blocks.

View provides the fundamental view architecture that forms the foundation of all Terminal.Gui user interface elements. This namespace contains the base View class, adornment system, layout primitives, and core view behaviors that enable the rich UI capabilities of Terminal.Gui.

The View system implements the complete view lifecycle, coordinate systems, event handling, focus management, and the innovative adornment system that separates content from visual decoration.

Key Components

View - Base class for all UI elements with complete lifecycle management
Adornment - Visual decorations (Margin, Border, Padding) outside content area
Viewport - Scrollable window into view content with built-in scrolling support
ViewArrangement - Flags controlling user interaction (Movable, Resizable, etc.)
Pos and Dim - Flexible positioning and sizing system with relative and absolute options

View Architecture

Hierarchy: SuperView/SubView relationships with automatic lifecycle management
Coordinate Systems: Multiple coordinate spaces (Frame, Viewport, Content, Screen)
Layout Engine: Automatic positioning and sizing with constraint-based layout
Event System: Comprehensive event handling with cancellation support
Focus Management: Built-in keyboard navigation and focus chain management

Example Usage

// Create a view with a Border adornment and Title
var view = new View()
{
    X = Pos.Center(),
    Y = Pos.Center(),
    Width = Dim.Percent(50),
    Height = Dim.Percent(30),
    Title = "My View",
    BorderStyle = LineStyle.Rounded
};

// Enable user arrangement
view.Arrangement = ViewArrangement.Movable | ViewArrangement.Resizable;

// Add to SuperView 
superView.Add(view);

View Deep Dive - Comprehensive view system documentation
List of Views - List of all built-in views
Layout Deep Dive - Layout system and coordinate spaces
Arrangement Deep Dive - User interaction and view arrangement
Navigation Deep Dive - Focus management and keyboard navigation
Scrolling Deep Dive - Built-in scrolling capabilities
Events Deep Dive - Event handling patterns

Classes

AddOrSubtractExtensions: Extension methods for the AddOrSubtract enum type.

Adornment: Adornments are a special form of View that appear outside the Viewport: Margin, Border, and Padding. They are defined using the Thickness class, which specifies the thickness of the sides of a rectangle.

AdvanceFocusEventArgs: The event arguments for AdvanceFocus(NavigationDirection, TabBehavior?) events.

Aligner: Aligns items within a container based on the specified Alignment. Both horizontal and vertical alignments are supported.

AlignmentExtensions: Extension methods for the Alignment enum type.

AlignmentModesExtensions: Extension methods for the AlignmentModes enum type.

Border: The Border for a View. Accessed via Border

BorderSettingsExtensions: Extension methods for the BorderSettings enum type.

Dim

A Dim object describes the dimensions of a View. Dim is the type of the Width and Height properties of View.

Integer values are implicitly convertible to an absolute Dim. These objects are created using the static methods described below. The Dim objects can be combined with the addition and subtraction operators.

DimAbsolute: Represents a dimension that is a fixed size.

DimAuto: Represents a dimension that automatically sizes the view to fit all the view's Content, SubViews, and/or Text.

DimAutoStyleExtensions: Extension methods for the DimAutoStyle enum type.

DimCombine: Represents a dimension that is a combination of two other dimensions.

DimFill: Represents a dimension that fills the dimension, leaving the specified margin.

DimFunc: Represents a function Dim object that computes the dimension by executing the provided function.

DimPercent: Represents a dimension that is a percentage of the width or height of the SuperView.

DimPercentModeExtensions: Extension methods for the DimPercentMode enum type.

DimView: Represents a dimension that tracks the Height or Width of the specified View.

DimensionExtensions: Extension methods for the Dimension enum type.

DrawAdornmentsEventArgs: Provides data for events that allow cancellation of adornment drawing in the Cancellable Work Pattern (CWP).

DrawContext: Tracks the region that has been drawn during Draw(DrawContext?). This is primarily in support of Transparent.

DrawEventArgs: Event args for draw events

HasFocusEventArgs: The event arguments for HasFocus events.

LayoutEventArgs: Event arguments for the SubViewsLaidOut event.

LayoutException: Represents an exception that is thrown when a layout operation fails.

Margin: The Margin for a View. Accessed via Margin

OrientationHelper: Helper class for implementing IOrientation.

Padding: The Padding for a View. Accessed via Padding

Pos: Describes the position of a View which can be an absolute value, a percentage, centered, or relative to the ending dimension. Integer values are implicitly convertible to an absolute Pos. These objects are created using the static methods Percent, AnchorEnd, and Center. The Pos objects can be combined with the addition and subtraction operators.

PosAbsolute: Represents an absolute position in the layout. This is used to specify a fixed position in the layout.

PosAlign: Enables alignment of a set of views.

PosAnchorEnd: Represents a position anchored to the end (right side or bottom).

PosCenter: Represents a position that is centered.

PosCombine: Represents a position that is a combination of two other positions.

PosFunc: Represents a position that is computed by executing a function that returns an integer position.

PosPercent: Represents a position that is a percentage of the width or height of the SuperView.

PosView: Represents a position that is anchored to the side of another view.

SideExtensions: Extension methods for the Side enum type.

SizeChangedEventArgs: Args for events about Size (e.g. Resized)

StackExtensions: Extension of Stack<T> helper to work with specific IEqualityComparer<T>

SuperViewChangedEventArgs: Args for events where the SuperView of a View is changed (e.g. Removed).

View

View is the base class all visible elements. View can render itself and contains zero or more nested views, called SubViews. View provides basic functionality for layout, arrangement, and drawing. In addition, View provides keyboard and mouse event handling.

See the View Deep Dive for more.

ViewDiagnosticFlagsExtensions: Extension methods for the ViewDiagnosticFlags enum type.

ViewEventArgs: Args for events that relate to specific View

Interfaces

IDesignable: Interface declaring common functionality useful for designer implementations.

IOrientation: Implement this interface to provide orientation support.

Enums

AddOrSubtract: Describes whether an operation should add or subtract values.

Alignment: Determines the position of items when arranged in a container.

AlignmentModes: Determines alignment modes for Alignment.

BorderSettings: Determines the settings for Border.

DimAutoStyle: Specifies how Auto(DimAutoStyle, Dim?, Dim?) will compute the dimension.

DimPercentMode: Indicates the mode for a DimPercent object.

Dimension: Indicates the dimension for Dim operations.

MouseState: Used to describe the state of the mouse in relation to a View (MouseState) and to specify visual effects, such as highlighting a button when the mouse is over it or changing the appearance of a view when the mouse is pressed (HighlightStates).

NavigationDirection: Indicates navigation direction.

Orientation: Direction of an element (horizontal or vertical)

ShadowStyle: Defines the style of shadow to be drawn on the right and bottom sides of the View.

Side: Indicates the side for Pos operations.

TabBehavior: Describes how TabStop behaves. A TabStop is a stop-point for keyboard navigation between Views.

ViewArrangement: Describes what user actions are enabled for arranging a View within it's SuperView . See Arrangement.

ViewDiagnosticFlags: Enables diagnostic functions for View.

ViewportSettingsFlags: Settings for how the Viewport behaves.

Delegates

View.CommandImplementation: Function signature commands.

Table of Contents