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Terminal.Gui/Terminal.Gui/View/Layout/Pos.cs
2024-05-19 07:46:51 -07:00

387 lines
17 KiB
C#

#nullable enable
using System.ComponentModel;
namespace Terminal.Gui;
/// <summary>
/// Describes the position of a <see cref="View"/> which can be an absolute value, a percentage, centered, or
/// relative to the ending dimension. Integer values are implicitly convertible to an absolute <see cref="Pos"/>. These
/// objects are created using the static methods Percent, AnchorEnd, and Center. The <see cref="Pos"/> objects can be
/// combined with the addition and subtraction operators.
/// </summary>
/// <remarks>
/// <para>Use the <see cref="Pos"/> objects on the X or Y properties of a view to control the position.</para>
/// <para>
/// These can be used to set the absolute position, when merely assigning an integer value (via the implicit
/// integer to <see cref="Pos"/> conversion), and they can be combined to produce more useful layouts, like:
/// Pos.Center - 3, which would shift the position of the <see cref="View"/> 3 characters to the left after
/// centering for example.
/// </para>
/// <para>
/// Reference coordinates of another view by using the methods Left(View), Right(View), Bottom(View), Top(View).
/// The X(View) and Y(View) are aliases to Left(View) and Top(View) respectively.
/// </para>
/// <para>
/// <list type="table">
/// <listheader>
/// <term>Pos Object</term> <description>Description</description>
/// </listheader>
/// <item>
/// <term>
/// <see cref="Pos.Align"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that aligns a set of views.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Func"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that computes the position by executing the provided
/// function. The function will be called every time the position is needed.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Percent(int)"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that is a percentage of the width or height of the
/// SuperView.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.AnchorEnd()"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that is anchored to the end (right side or bottom) of
/// the dimension, useful to flush the layout from the right or bottom.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Center"/>
/// </term>
/// <description>Creates a <see cref="Pos"/> object that can be used to center the <see cref="View"/>.</description>
/// </item>
/// <item>
/// <term>
/// <see cref="Absolute"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that is an absolute position based on the specified
/// integer value.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Left"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that tracks the Left (X) position of the specified
/// <see cref="View"/>.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.X(View)"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that tracks the Left (X) position of the specified
/// <see cref="View"/>.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Top(View)"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that tracks the Top (Y) position of the specified
/// <see cref="View"/>.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Y(View)"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that tracks the Top (Y) position of the specified
/// <see cref="View"/>.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Right(View)"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that tracks the Right (X+Width) coordinate of the
/// specified <see cref="View"/>.
/// </description>
/// </item>
/// <item>
/// <term>
/// <see cref="Pos.Bottom(View)"/>
/// </term>
/// <description>
/// Creates a <see cref="Pos"/> object that tracks the Bottom (Y+Height) coordinate of the
/// specified <see cref="View"/>
/// </description>
/// </item>
/// </list>
/// </para>
/// </remarks>
public abstract class Pos
{
#region static Pos creation methods
/// <summary>Creates a <see cref="Pos"/> object that is an absolute position based on the specified integer value.</summary>
/// <returns>The Absolute <see cref="Pos"/>.</returns>
/// <param name="position">The value to convert to the <see cref="Pos"/>.</param>
public static Pos Absolute (int position) { return new PosAbsolute (position); }
/// <summary>
/// Creates a <see cref="Pos"/> object that aligns a set of views according to the specified alignment setting.
/// </summary>
/// <param name="alignment">The alignment.</param>
/// <param name="mode">The optional alignment modes.</param>
/// <param name="groupId">
/// The optional, unique identifier for the set of views to align according to
/// <paramref name="alignment"/>.
/// </param>
/// <returns></returns>
public static Pos Align (Alignment alignment, AlignmentModes mode = AlignmentModes.StartToEnd | AlignmentModes.AddSpaceBetweenItems, int groupId = 0)
{
return new PosAlign (alignment, mode, groupId);
}
/// <summary>
/// Creates a <see cref="Pos"/> object that is anchored to the end (right side or
/// bottom) of the SuperView's Content Area, minus the respective size of the View. This is equivalent to using
/// <see cref="Pos.AnchorEnd(int)"/>,
/// with an offset equivalent to the View's respective dimension.
/// </summary>
/// <returns>The <see cref="Pos"/> object anchored to the end (the bottom or the right side) minus the View's dimension.</returns>
/// <example>
/// This sample shows how align a <see cref="Button"/> to the bottom-right the SuperView.
/// <code>
/// anchorButton.X = Pos.AnchorEnd ();
/// anchorButton.Y = Pos.AnchorEnd ();
/// </code>
/// </example>
public static Pos AnchorEnd () { return new PosAnchorEnd (); }
/// <summary>
/// Creates a <see cref="Pos"/> object that is anchored to the end (right side or bottom) of the SuperView's Content
/// Area,
/// useful to flush the layout from the right or bottom. See also <see cref="Pos.AnchorEnd()"/>, which uses the view
/// dimension to ensure the view is fully visible.
/// </summary>
/// <returns>The <see cref="Pos"/> object anchored to the end (the bottom or the right side).</returns>
/// <param name="offset">The view will be shifted left or up by the amount specified.</param>
/// <example>
/// This sample shows how align a 10 column wide <see cref="Button"/> to the bottom-right the SuperView.
/// <code>
/// anchorButton.X = Pos.AnchorEnd (10);
/// anchorButton.Y = 1
/// </code>
/// </example>
public static Pos AnchorEnd (int offset)
{
if (offset < 0)
{
throw new ArgumentException (@"Must be positive", nameof (offset));
}
return new PosAnchorEnd (offset);
}
/// <summary>Creates a <see cref="Pos"/> object that can be used to center the <see cref="View"/>.</summary>
/// <returns>The center Pos.</returns>
/// <example>
/// This creates a <see cref="TextView"/> centered horizontally, is 50% of the way down, is 30% the height, and
/// is 80% the width of the <see cref="View"/> it added to.
/// <code>
/// var textView = new TextView () {
/// X = Pos.Center (),
/// Y = Pos.Percent (50),
/// Width = Dim.Percent (80),
/// Height = Dim.Percent (30),
/// };
/// </code>
/// </example>
public static Pos Center () { return new PosCenter (); }
/// <summary>
/// Creates a <see cref="Pos"/> object that computes the position by executing the provided function. The function
/// will be called every time the position is needed.
/// </summary>
/// <param name="function">The function to be executed.</param>
/// <returns>The <see cref="Pos"/> returned from the function.</returns>
public static Pos Func (Func<int> function) { return new PosFunc (function); }
/// <summary>Creates a percentage <see cref="Pos"/> object</summary>
/// <returns>The percent <see cref="Pos"/> object.</returns>
/// <param name="percent">A value between 0 and 100 representing the percentage.</param>
/// <example>
/// This creates a <see cref="TextField"/> centered horizontally, is 50% of the way down, is 30% the height, and
/// is 80% the width of the <see cref="View"/> it added to.
/// <code>
/// var textView = new TextField {
/// X = Pos.Center (),
/// Y = Pos.Percent (50),
/// Width = Dim.Percent (80),
/// Height = Dim.Percent (30),
/// };
/// </code>
/// </example>
public static Pos Percent (int percent)
{
if (percent is < 0)
{
throw new ArgumentException ("Percent value must be positive.");
}
return new PosPercent (percent);
}
/// <summary>Creates a <see cref="Pos"/> object that tracks the Top (Y) position of the specified <see cref="View"/>.</summary>
/// <returns>The <see cref="Pos"/> that depends on the other view.</returns>
/// <param name="view">The <see cref="View"/> that will be tracked.</param>
public static Pos Top (View view) { return new PosView (view, Side.Top); }
/// <summary>Creates a <see cref="Pos"/> object that tracks the Top (Y) position of the specified <see cref="View"/>.</summary>
/// <returns>The <see cref="Pos"/> that depends on the other view.</returns>
/// <param name="view">The <see cref="View"/> that will be tracked.</param>
public static Pos Y (View view) { return new PosView (view, Side.Top); }
/// <summary>Creates a <see cref="Pos"/> object that tracks the Left (X) position of the specified <see cref="View"/>.</summary>
/// <returns>The <see cref="Pos"/> that depends on the other view.</returns>
/// <param name="view">The <see cref="View"/> that will be tracked.</param>
public static Pos Left (View view) { return new PosView (view, Side.Left); }
/// <summary>Creates a <see cref="Pos"/> object that tracks the Left (X) position of the specified <see cref="View"/>.</summary>
/// <returns>The <see cref="Pos"/> that depends on the other view.</returns>
/// <param name="view">The <see cref="View"/> that will be tracked.</param>
public static Pos X (View view) { return new PosView (view, Side.Left); }
/// <summary>
/// Creates a <see cref="Pos"/> object that tracks the Bottom (Y+Height) coordinate of the specified
/// <see cref="View"/>
/// </summary>
/// <returns>The <see cref="Pos"/> that depends on the other view.</returns>
/// <param name="view">The <see cref="View"/> that will be tracked.</param>
public static Pos Bottom (View view) { return new PosView (view, Side.Bottom); }
/// <summary>
/// Creates a <see cref="Pos"/> object that tracks the Right (X+Width) coordinate of the specified
/// <see cref="View"/>.
/// </summary>
/// <returns>The <see cref="Pos"/> that depends on the other view.</returns>
/// <param name="view">The <see cref="View"/> that will be tracked.</param>
public static Pos Right (View view) { return new PosView (view, Side.Right); }
#endregion static Pos creation methods
#region virtual methods
/// <summary>
/// Gets the starting point of an element based on the size of the parent element (typically
/// <c>Superview.ContentSize</c>).
/// This method is meant to be overridden by subclasses to provide different ways of calculating the starting point.
/// This method is used
/// internally by the layout system to determine where a View should be positioned.
/// </summary>
/// <param name="size">The size of the parent element (typically <c>Superview.ContentSize</c>).</param>
/// <returns>
/// An integer representing the calculated position. The way this position is calculated depends on the specific
/// subclass of Pos that is used. For example, PosAbsolute returns a fixed position, PosAnchorEnd returns a
/// position that is anchored to the end of the layout, and so on.
/// </returns>
internal virtual int GetAnchor (int size) { return 0; }
/// <summary>
/// Calculates and returns the final position of a <see cref="View"/> object. It takes into account the dimension of
/// the
/// superview and the dimension of the view itself.
/// </summary>
/// <remarks>
/// </remarks>
/// <param name="superviewDimension">
/// The dimension of the superview. This could be the width for x-coordinate calculation or the
/// height for y-coordinate calculation.
/// </param>
/// <param name="dim">The dimension of the View. It could be the current width or height.</param>
/// <param name="us">The View that holds this Pos object.</param>
/// <param name="dimension">Width or Height</param>
/// <returns>
/// The calculated position of the View. The way this position is calculated depends on the specific subclass of Pos
/// that
/// is used.
/// </returns>
internal virtual int Calculate (int superviewDimension, Dim dim, View us, Dimension dimension) { return GetAnchor (superviewDimension); }
/// <summary>
/// Diagnostics API to determine if this Pos object references other views.
/// </summary>
/// <returns></returns>
internal virtual bool ReferencesOtherViews () { return false; }
#endregion virtual methods
#region operators
/// <summary>Adds a <see cref="Terminal.Gui.Pos"/> to a <see cref="Terminal.Gui.Pos"/>, yielding a new <see cref="Pos"/>.</summary>
/// <param name="left">The first <see cref="Terminal.Gui.Pos"/> to add.</param>
/// <param name="right">The second <see cref="Terminal.Gui.Pos"/> to add.</param>
/// <returns>The <see cref="Pos"/> that is the sum of the values of <c>left</c> and <c>right</c>.</returns>
public static Pos operator + (Pos left, Pos right)
{
if (left is PosAbsolute && right is PosAbsolute)
{
return new PosAbsolute (left.GetAnchor (0) + right.GetAnchor (0));
}
var newPos = new PosCombine (AddOrSubtract.Add, left, right);
if (left is PosView view)
{
view.Target.SetNeedsLayout ();
}
return newPos;
}
/// <summary>Creates an Absolute <see cref="Pos"/> from the specified integer value.</summary>
/// <returns>The Absolute <see cref="Pos"/>.</returns>
/// <param name="n">The value to convert to the <see cref="Pos"/> .</param>
public static implicit operator Pos (int n) { return new PosAbsolute (n); }
/// <summary>
/// Subtracts a <see cref="Terminal.Gui.Pos"/> from a <see cref="Terminal.Gui.Pos"/>, yielding a new
/// <see cref="Pos"/>.
/// </summary>
/// <param name="left">The <see cref="Terminal.Gui.Pos"/> to subtract from (the minuend).</param>
/// <param name="right">The <see cref="Terminal.Gui.Pos"/> to subtract (the subtrahend).</param>
/// <returns>The <see cref="Pos"/> that is the <c>left</c> minus <c>right</c>.</returns>
public static Pos operator - (Pos left, Pos right)
{
if (left is PosAbsolute && right is PosAbsolute)
{
return new PosAbsolute (left.GetAnchor (0) - right.GetAnchor (0));
}
var newPos = new PosCombine (AddOrSubtract.Subtract, left, right);
if (left is PosView view)
{
view.Target.SetNeedsLayout ();
}
return newPos;
}
#endregion operators
}