GetContentSize() does not behave according to documentation

[Error-String-Expected-Got-Nil]

Per View.GetContentSize() remarks documentation:

Terminal.Gui/Terminal.Gui/View/View.Content.cs

Lines 68 to 73 in b46b778

	/// <para>
	/// If the content size was not explicitly set by <see cref="SetContentSize"/>, and the View has visible subviews, <see cref="GetContentSize ()"/> will return the
	/// maximum
	/// position + dimension of the SubViews, supporting <see cref="Dim.Auto"/> with the
	/// <see cref="DimAutoStyle.Content"/> flag set.
	/// </para>

However, if we scroll down a bit to the function itself:

Terminal.Gui/Terminal.Gui/View/View.Content.cs

Line 87 in b46b778

public Size GetContentSize () { return _contentSize ?? Viewport.Size; }

_contentSize is only ever set in View.SetContentSize() and View.ContentSizeTracksViewport. The latter only nullifies _contentSize when set to true, and the former just sets it directly after doing some error checking.

I'm unsure if this is simply a feature that was never implemented (but should be), or if the documentation is just outdated/wrong.

If there is a function that does what the remark describes, it should probably be mentioned there instead.

[tig]

I'll look tomorrow. I iterated on this many a time so it's not surprising I missed something.

I really appreciate you reporting it.

[tig]

Ok, I've re-reviewed the code.

I'll submit a PR that changes View.Content.cs to this:

public partial class View
{
    #region Content Area

    // nullable holder of developer specified Content Size. If null then the developer did not
    // explicitly set it and contentsize will be calculated dynamically.
    internal Size? _contentSize;

    /// <summary>
    ///     Sets the size of the View's content.
    /// </summary>
    /// <remarks>
    ///     <para>
    ///         See the View Layout Deep Dive for more information:
    ///         <see href="https://gui-cs.github.io/Terminal.GuiV2Docs/docs/layout.html"/>
    ///     </para>
    ///     <para>
    ///         Negative sizes are not supported.
    ///     </para>
    ///     <para>
    ///         If not explicitly set to a non-<see langword="null"/> value, and the View has Subviews,
    ///         <see cref="GetContentSize ()"/> will return
    ///         the size of the <see cref="Viewport"/>.
    ///     </para>
    ///     <para>
    ///         If set to a non-<see langword="null"/> value, <see cref="Viewport"/> describes the portion of the content
    ///         currently visible to the user. This enables
    ///         virtual scrolling and the behavior of <see cref="DimAutoStyle.Content"/> will be to use
    ///         <see cref="GetContentSize ()"/> to determine the size
    ///         of the view.
    ///     </para>
    /// </remarks>
    public void SetContentSize (Size? contentSize)

Note it was also incorrect in saying "and the View has visible subviews" before too.

When I was working on this, I had this idea (which was a bad one):

• Need a property on View that says "Ignore for Layout" #3508

I then failed to re-read the API doc closely enough. Thanks again for pointing this out.

Oh, if someone wants a view to be sized to the "maximum position+dimension of all subviews" they can just do this:

Width = Dim.Auto (DimAutosStyle.Content);

There is no public API to just calculate said width. That code is spaghetti in DimAuto.cs...