#nullable enable
using System.ComponentModel;
using System.Diagnostics;
namespace Terminal.Gui;
#region API Docs
///
/// 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.
///
///
///
///
/// TermDefinition
///
/// -
/// SubView
///
/// A View that is contained in another view and will be rendered as part of the containing view's
/// ContentArea. SubViews are added to another view via the ` method. A View
/// may only be a SubView of a single View.
///
///
/// -
/// SuperViewThe View that is a container for SubViews.
///
/// -
/// Input
///
///
/// Key Bindings is the preferred way of handling keyboard input in View implementations.
/// The View calls
/// to declare
/// it supports a particular command and then uses
/// to indicate which key presses will invoke the command.
///
///
/// Mouse Bindings is the preferred way of handling mouse input in View implementations. The View calls
/// to declare
/// it supports a
/// particular command and then uses to indicate which mouse events will
/// invoke the command.
///
///
/// See the
///
/// Mouse
/// Deep Dive
///
/// and
///
/// Keyboard
/// Deep Dive
///
/// for more information.
///
///
///
/// -
/// Layout
///
///
/// Terminal.Gui provides a rich system for how View objects are laid out relative to each other. The
/// layout system also defines how coordinates are specified.
///
///
/// The , , , and properties are
/// and objects that dynamically update the position of a view. The
/// X and Y properties are of type and you can use either absolute positions,
/// percentages, or anchor points. The Width and Height properties are of type and
/// can use absolute position, percentages, and anchors. These are useful as they will take care of
/// repositioning views when view's adornments are resized or if the terminal size changes.
///
///
/// See the
///
/// Layout
/// Deep Dive
///
/// for more information.
///
///
///
/// -
/// Arrangement
///
///
/// Complimenting the Layout system, controls how the user can use the mouse
/// and keyboard to arrange views and enables either Tiled or Overlapped layouts.
///
///
/// See the
///
/// Arrangement
/// Deep Dive
///
/// for more information.
///
///
///
/// -
/// Drawing
///
///
/// Apps draw using the and APIs. Move selects the
/// column and row of the Cell and AddRune places
/// the specified glyph in that cell using the that was most recently set via
/// .
/// The ConsoleDriver caches all changed Cells and efficiently outputs them to the terminal each
/// iteration of the Application. In other words, Terminal.Gui uses deferred rendering.
///
///
/// The View draw APIs all take coordinates specified in Viewport-Relative coordinates. That is,
/// (0,0) is the top-left cell visible to the user.
///
///
/// If a View need to redraw because something changed within it's Content Area it can call
/// .
///
///
/// Terminal.Gui supports the full range of Unicode/wide characters.
/// This includes emoji, CJK characters, and other wide characters. For Unicode characters that require
/// more than one cell,
/// AddRune and the ConsoleDriver automatically manage the cells. Extension methods to Rune are
/// provided to determine if a Rune is a wide character and to get the width of a Rune.
///
///
/// The provides consistent colors across all views. The
/// is inherited from the . The
/// is used to set the for drawing.
///
/// The class represents a color. It provides automatic mapping between the legacy
/// 4-bit (16-color) system and 24-bit colors. It contains properties for the red, green, and blue
/// components of the color.
/// The Color class also contains a static property for each of the 16 ANSI colors. Use
/// to change the colors used when drawing.
///
///
///
/// Clipping enables better performance by ensuring on regions of the terminal that need to be drawn
/// actually get drawn by the ConsoleDriver. Terminal.Gui supports non-rectangular clip regions with
/// .
/// There is an -managed clip region. Developers cannot change this directly,
/// but can use , , and to
/// modify the clip region.
///
///
/// provides auto join, a smart TUI drawing system that automatically selects
/// the correct line/box drawing glyphs for intersections making drawing complex shapes easy.
///
///
/// A set of static properties are provided for the common glyphs used in TUI apps. See
/// .
///
///
/// See the
///
/// Drawing
/// Deep Dive
///
/// for more information.
///
///
///
/// -
/// Text
///
///
/// A rich text formatting engine is provided in . TextFormatter provides
/// methods for formatting text with horizontal and vertical alignment, word wrapping, and hotkeys.
///
///
/// See the
///
/// Navigation
/// Deep Dive
///
/// for more information.
///
///
///
/// -
/// Navigation
///
///
/// Navigation refers to the user experience for moving focus between views in the application
/// view-hierarchy. Focus is a concept that is used to describe which View is currently receiving user
/// input. Only
/// Views that are
/// , , and will receive focus. NOTE:
/// is by default.
///
///
/// Views that are focusable should override to make sure that the cursor
/// is
/// placed in a location that makes sense. Some terminals do not have a way of hiding the cursor, so it
/// can be
/// distracting to have the cursor left at the last focused view. So views should make sure that they
/// place the
/// cursor in a visually sensible place. The default implementation of
/// will place the
/// cursor at either the hotkey (if defined) or 0,0.
///
///
/// See the
///
/// Navigation
/// Deep Dive
///
/// for more information.
///
///
///
/// -
/// Scrolling
///
///
/// The ability to scroll content is built into View. The represents the
/// scrollable "viewport" into the View's Content Area (which is defined by the return value of
/// ).
///
///
/// Terminal.Gui also provides the ability show a visual scroll bar that responds to mouse input. This
/// ability is not enabled by default given how precious TUI screen real estate is.
/// Use and to enable this feature.
///
///
/// Use to adjust the behavior of scrolling.
///
///
/// See the
///
/// Scrolling
/// Deep Dive
///
/// for more information.
///
///
///
///
///
/// Views can opt in to more sophisticated initialization by implementing overrides to
/// and which will be called
/// when the view is added to a .
///
///
/// If first-run-only initialization is preferred, overrides to can
/// be implemented, in which case the methods will only be called if
/// is . This allows proper
/// inheritance hierarchies to override base class layout code optimally by doing so only on
/// first run, instead of on every run.
///
/// See for an overview of View keyboard handling.
///
#endregion API Docs
public partial class View : IDisposable, ISupportInitializeNotification
{
#region Constructors and Initialization
/// Gets or sets arbitrary data for the view.
/// This property is not used internally.
public object? Data { get; set; }
/// Gets or sets an identifier for the view;
/// The identifier.
/// The id should be unique across all Views that share a SuperView.
public string Id { get; set; } = "";
///
/// Points to the current driver in use by the view, it is a convenience property for simplifying the development
/// of new views.
///
public static IConsoleDriver? Driver => Application.Driver;
/// Initializes a new instance of .
///
///
/// Use , , , and properties to dynamically
/// control the size and location of the view.
///
///
public View ()
{
#if DEBUG_IDISPOSABLE
Instances.Add (this);
#endif
SetupAdornments ();
SetupCommands ();
SetupKeyboard ();
SetupMouse ();
SetupText ();
SetupScrollBars ();
}
///
/// Raised once when the is being initialized for the first time. Allows
/// configurations and assignments to be performed before the being shown.
/// View implements to allow for more sophisticated initialization.
///
public event EventHandler? Initialized;
///
/// Get or sets if the has been initialized (via
/// and ).
///
///
/// If first-run-only initialization is preferred, overrides to
/// can be implemented, in which case the
/// methods will only be called if
/// is . This allows proper
/// inheritance hierarchies to override base class layout code optimally by doing so only on first
/// run, instead of on every run.
///
public virtual bool IsInitialized { get; set; }
/// Signals the View that initialization is starting. See .
///
///
/// Views can opt-in to more sophisticated initialization by implementing overrides to
/// and which will be called
/// when the is initialized.
///
///
/// If first-run-only initialization is preferred, overrides to can
/// be implemented too, in which case the methods will only be called if
/// is . This allows proper
/// inheritance hierarchies to override base class layout code optimally by doing so only on
/// first run, instead of on every run.
///
///
public virtual void BeginInit ()
{
if (IsInitialized)
{
throw new InvalidOperationException ("The view is already initialized.");
}
#if AUTO_CANFOCUS
_oldCanFocus = CanFocus;
_oldTabIndex = _tabIndex;
#endif
BeginInitAdornments ();
if (_subviews?.Count > 0)
{
foreach (View view in _subviews)
{
if (!view.IsInitialized)
{
view.BeginInit ();
}
}
}
}
// TODO: Implement logic that allows EndInit to throw if BeginInit has not been called
// TODO: See EndInit_Called_Without_BeginInit_Throws test.
/// Signals the View that initialization is ending. See .
///
/// Initializes all Subviews and Invokes the event.
///
public virtual void EndInit ()
{
if (IsInitialized)
{
throw new InvalidOperationException ("The view is already initialized.");
}
IsInitialized = true;
EndInitAdornments ();
// TODO: Move these into ViewText.cs as EndInit_Text() to consolidate.
// TODO: Verify UpdateTextDirection really needs to be called here.
// These calls were moved from BeginInit as they access Viewport which is indeterminate until EndInit is called.
UpdateTextDirection (TextDirection);
UpdateTextFormatterText ();
if (_subviews is { })
{
foreach (View view in _subviews)
{
if (!view.IsInitialized)
{
view.EndInit ();
}
}
}
// TODO: Figure out how to move this out of here and just depend on LayoutNeeded in Mainloop
Layout (); // the EventLog in AllViewsTester fails to layout correctly if this is not here (convoluted Dim.Fill(Func)).
SetNeedsLayout ();
Initialized?.Invoke (this, EventArgs.Empty);
}
#endregion Constructors and Initialization
#region Visibility
private bool _enabled = true;
/// Gets or sets a value indicating whether this can respond to user interaction.
public bool Enabled
{
get => _enabled;
set
{
if (_enabled == value)
{
return;
}
_enabled = value;
if (!_enabled && HasFocus)
{
HasFocus = false;
}
if (_enabled
&& CanFocus
&& Visible
&& !HasFocus
&& SuperView is null or { HasFocus: true, Visible: true, Enabled: true, Focused: null })
{
SetFocus ();
}
OnEnabledChanged ();
SetNeedsDraw ();
if (Border is { })
{
Border.Enabled = _enabled;
}
if (_subviews is null)
{
return;
}
foreach (View view in _subviews)
{
view.Enabled = Enabled;
}
}
}
/// Raised when the value is being changed.
public event EventHandler? EnabledChanged;
// TODO: Change this event to match the standard TG event model.
/// Invoked when the property from a view is changed.
public virtual void OnEnabledChanged () { EnabledChanged?.Invoke (this, EventArgs.Empty); }
private bool _visible = true;
// TODO: Remove virtual once Menu/MenuBar are removed. MenuBar is the only override.
/// Gets or sets a value indicating whether this is visible.
public virtual bool Visible
{
get => _visible;
set
{
if (_visible == value)
{
return;
}
if (OnVisibleChanging ())
{
return;
}
CancelEventArgs args = new (in _visible, ref value);
VisibleChanging?.Invoke (this, args);
if (args.Cancel)
{
return;
}
_visible = value;
if (!_visible)
{
if (HasFocus)
{
HasFocus = false;
}
}
if (_visible
&& CanFocus
&& Enabled
&& !HasFocus
&& SuperView is null or { HasFocus: true, Visible: true, Enabled: true, Focused: null })
{
SetFocus ();
}
OnVisibleChanged ();
VisibleChanged?.Invoke (this, EventArgs.Empty);
SetNeedsLayout ();
SuperView?.SetNeedsLayout ();
SetNeedsDraw ();
if (SuperView is { })
{
SuperView?.SetNeedsDraw ();
}
else
{
Application.ClearScreenNextIteration = true;
}
}
}
/// Called when is changing. Can be cancelled by returning .
protected virtual bool OnVisibleChanging () { return false; }
///
/// Raised when the value is being changed. Can be cancelled by setting Cancel to
/// .
///
public event EventHandler>? VisibleChanging;
/// Called when has changed.
protected virtual void OnVisibleChanged () { }
/// Raised when has changed.
public event EventHandler? VisibleChanged;
///
/// INTERNAL Indicates whether all views up the Superview hierarchy are visible.
///
/// The view to test.
///
/// if `view.Visible` is or any Superview is not visible,
/// otherwise.
///
internal static bool CanBeVisible (View view)
{
if (!view.Visible)
{
return false;
}
for (View? c = view.SuperView; c != null; c = c.SuperView)
{
if (!c.Visible)
{
return false;
}
}
return true;
}
#endregion Visibility
#region Title
private string _title = string.Empty;
/// Gets the used to format .
internal TextFormatter TitleTextFormatter { get; init; } = new ();
///
/// The title to be displayed for this . The title will be displayed if .
/// is greater than 0. The title can be used to set the
/// for the view by prefixing character with (e.g. "T_itle").
///
///
///
/// Set the to enable hotkey support. To disable Title-based hotkey support set
/// to (Rune)0xffff.
///
///
/// Only the first HotKey specifier found in is supported.
///
///
/// To cause the hotkey to be rendered with ,
/// set View. to the desired character.
///
///
/// The title.
public string Title
{
get
{
#if DEBUG_IDISPOSABLE
if (WasDisposed)
{
throw new ObjectDisposedException (GetType ().FullName);
}
#endif
return _title;
}
set
{
#if DEBUG_IDISPOSABLE
if (WasDisposed)
{
throw new ObjectDisposedException (GetType ().FullName);
}
#endif
if (value == _title)
{
return;
}
if (!OnTitleChanging (ref value))
{
string old = _title;
_title = value;
TitleTextFormatter.Text = _title;
SetTitleTextFormatterSize ();
SetHotKeyFromTitle ();
SetNeedsDraw ();
#if DEBUG
if (string.IsNullOrEmpty (Id))
{
Id = _title;
}
#endif // DEBUG
OnTitleChanged ();
}
}
}
private void SetTitleTextFormatterSize ()
{
TitleTextFormatter.ConstrainToSize = new (
TextFormatter.GetWidestLineLength (TitleTextFormatter.Text)
- (TitleTextFormatter.Text?.Contains ((char)HotKeySpecifier.Value) == true
? Math.Max (HotKeySpecifier.GetColumns (), 0)
: 0),
1);
}
// TODO: Change this event to match the standard TG event model.
/// Called when the has been changed. Invokes the event.
protected void OnTitleChanged () { TitleChanged?.Invoke (this, new (in _title)); }
///
/// Called before the changes. Invokes the event, which can
/// be cancelled.
///
/// The new to be replaced.
/// `true` if an event handler canceled the Title change.
protected bool OnTitleChanging (ref string newTitle)
{
CancelEventArgs args = new (ref _title, ref newTitle);
TitleChanging?.Invoke (this, args);
return args.Cancel;
}
/// Raised after the has been changed.
public event EventHandler>? TitleChanged;
///
/// Raised when the is changing. Set to `true`
/// to cancel the Title change.
///
public event EventHandler>? TitleChanging;
#endregion
/// Pretty prints the View
///
public override string ToString () { return $"{GetType ().Name}({Id}){Frame}"; }
private bool _disposedValue;
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
///
/// If disposing equals true, the method has been called directly or indirectly by a user's code. Managed and
/// unmanaged resources can be disposed. If disposing equals false, the method has been called by the runtime from
/// inside the finalizer and you should not reference other objects. Only unmanaged resources can be disposed.
///
///
protected virtual void Dispose (bool disposing)
{
LineCanvas.Dispose ();
DisposeMouse ();
DisposeKeyboard ();
DisposeAdornments ();
DisposeScrollBars ();
for (int i = InternalSubviews.Count - 1; i >= 0; i--)
{
View subview = InternalSubviews [i];
Remove (subview);
subview.Dispose ();
}
if (!_disposedValue)
{
if (disposing)
{
// TODO: dispose managed state (managed objects)
}
_disposedValue = true;
}
Debug.Assert (InternalSubviews.Count == 0);
}
///
/// Riased when the is being disposed.
///
public event EventHandler? Disposing;
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resource.
public void Dispose ()
{
// Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
Disposing?.Invoke (this, EventArgs.Empty);
Dispose (true);
GC.SuppressFinalize (this);
#if DEBUG_IDISPOSABLE
WasDisposed = true;
foreach (View instance in Instances.Where (x => x.WasDisposed).ToList ())
{
Instances.Remove (instance);
}
#endif
}
#if DEBUG_IDISPOSABLE
/// For debug purposes to verify objects are being disposed properly
public bool WasDisposed { get; set; }
/// For debug purposes to verify objects are being disposed properly
public int DisposedCount { get; set; } = 0;
/// For debug purposes
public static List Instances { get; set; } = [];
#endif
}