From af9c6d7846067f90029ba189b01ab7682a29ea00 Mon Sep 17 00:00:00 2001
From: Thomas Nind <31306100+tznind@users.noreply.github.com>
Date: Sat, 1 Mar 2025 16:36:13 +0000
Subject: [PATCH] Change LayoutAndDraw in v2 applications to simply set
 draw/layout flags instead of force a buffer refresh (#3943)

---
 Terminal.Gui/Application/Application.Run.cs     | 5 +++++
 Terminal.Gui/Application/ApplicationImpl.cs     | 6 ++++++
 Terminal.Gui/Application/IApplication.cs        | 7 +++++++
 Terminal.Gui/ConsoleDrivers/V2/ApplicationV2.cs | 8 ++++++++
 Terminal.Gui/ConsoleDrivers/V2/MainLoop.cs      | 3 +--
 5 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/Terminal.Gui/Application/Application.Run.cs b/Terminal.Gui/Application/Application.Run.cs
index fc6819aed..6906efd90 100644
--- a/Terminal.Gui/Application/Application.Run.cs
+++ b/Terminal.Gui/Application/Application.Run.cs
@@ -411,6 +411,11 @@ public static partial class Application // Run (Begin, Run, End, Stop)
     /// </summary>
     /// <param name="forceDraw">If <see langword="true"/> the entire View hierarchy will be redrawn. The default is <see langword="false"/> and should only be overriden for testing.</param>
     public static void LayoutAndDraw (bool forceDraw = false)
+    {
+        ApplicationImpl.Instance.LayoutAndDraw (forceDraw);
+    }
+
+    internal static void LayoutAndDrawImpl (bool forceDraw = false)
     {
         bool neededLayout = View.Layout (TopLevels.Reverse (), Screen.Size);
 
diff --git a/Terminal.Gui/Application/ApplicationImpl.cs b/Terminal.Gui/Application/ApplicationImpl.cs
index bf40f381b..49e1d4b52 100644
--- a/Terminal.Gui/Application/ApplicationImpl.cs
+++ b/Terminal.Gui/Application/ApplicationImpl.cs
@@ -294,4 +294,10 @@ public class ApplicationImpl : IApplication
     { 
         return Application.MainLoop?.TimedEvents.RemoveTimeout (token) ?? false;
     }
+
+    /// <inheritdoc />
+    public virtual void LayoutAndDraw (bool forceDraw)
+    {
+        Application.LayoutAndDrawImpl (forceDraw);
+    }
 }
diff --git a/Terminal.Gui/Application/IApplication.cs b/Terminal.Gui/Application/IApplication.cs
index bdd51046f..a6362b09e 100644
--- a/Terminal.Gui/Application/IApplication.cs
+++ b/Terminal.Gui/Application/IApplication.cs
@@ -182,4 +182,11 @@ public interface IApplication
     /// <see langword="false"/>
     /// if the timeout is not found.</returns>
     bool RemoveTimeout (object token);
+
+    /// <summary>
+    /// Causes any Toplevels that need layout to be laid out. Then draws any Toplevels that need display. Only Views that need to be laid out (see <see cref="View.NeedsLayout"/>) will be laid out.
+    /// Only Views that need to be drawn (see <see cref="View.NeedsDraw"/>) will be drawn.
+    /// </summary>
+    /// <param name="forceDraw">If <see langword="true"/> the entire View hierarchy will be redrawn. The default is <see langword="false"/> and should only be overriden for testing.</param>
+    void LayoutAndDraw (bool forceDraw);
 }
\ No newline at end of file
diff --git a/Terminal.Gui/ConsoleDrivers/V2/ApplicationV2.cs b/Terminal.Gui/ConsoleDrivers/V2/ApplicationV2.cs
index 5679f1913..36cd6a62c 100644
--- a/Terminal.Gui/ConsoleDrivers/V2/ApplicationV2.cs
+++ b/Terminal.Gui/ConsoleDrivers/V2/ApplicationV2.cs
@@ -232,4 +232,12 @@ public class ApplicationV2 : ApplicationImpl
 
     /// <inheritdoc/>
     public override bool RemoveTimeout (object token) { return _timedEvents.RemoveTimeout (token); }
+
+    /// <inheritdoc />
+    public override void LayoutAndDraw (bool forceDraw)
+    {
+        // No more ad-hoc drawing, you must wait for iteration to do it
+        Application.Top?.SetNeedsDraw();
+        Application.Top?.SetNeedsLayout ();
+    }
 }
diff --git a/Terminal.Gui/ConsoleDrivers/V2/MainLoop.cs b/Terminal.Gui/ConsoleDrivers/V2/MainLoop.cs
index 8c830aaa3..08575a1ba 100644
--- a/Terminal.Gui/ConsoleDrivers/V2/MainLoop.cs
+++ b/Terminal.Gui/ConsoleDrivers/V2/MainLoop.cs
@@ -130,8 +130,7 @@ public class MainLoop<T> : IMainLoop<T>
             {
                 Logging.Redraws.Add (1);
 
-                // TODO: Test only
-                Application.LayoutAndDraw (true);
+                Application.LayoutAndDrawImpl (true);
 
                 Out.Write (OutputBuffer);