From 1a9176e12f6400091e02edd02b8d4e844db465c5 Mon Sep 17 00:00:00 2001
From: CasualPokePlayer <50538166+CasualPokePlayer@users.noreply.github.com>
Date: Sat, 1 Jun 2024 14:01:01 -0700
Subject: [PATCH] Fix "double rendering" in Lua/ApiHawk gui stuff

---
 src/BizHawk.Bizware.Graphics/Interfaces/I2DRenderer.cs    | 6 ++++++
 src/BizHawk.Bizware.Graphics/Renderers/ImGui2DRenderer.cs | 3 +++
 src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs     | 2 +-
 .../DisplayManager/DisplayManagerBase.cs                  | 8 ++++++++
 src/BizHawk.Client.Common/IMainFormForApi.cs              | 2 +-
 src/BizHawk.Client.EmuHawk/IMainFormForTools.cs           | 2 +-
 src/BizHawk.Client.EmuHawk/MainForm.cs                    | 8 +++++++-
 7 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/BizHawk.Bizware.Graphics/Interfaces/I2DRenderer.cs b/src/BizHawk.Bizware.Graphics/Interfaces/I2DRenderer.cs
index bf80dd8cd09..6946de88e7e 100644
--- a/src/BizHawk.Bizware.Graphics/Interfaces/I2DRenderer.cs
+++ b/src/BizHawk.Bizware.Graphics/Interfaces/I2DRenderer.cs
@@ -29,6 +29,12 @@ public interface I2DRenderer : IDisposable
 		/// </summary>
 		void Clear();
 
+		/// <summary>
+		/// Discards any pending draw calls.
+		/// Similar to Clear(), except this won't insert a command to clear the target texture
+		/// </summary>
+		void Discard();
+
 		CompositingMode CompositingMode { set; }
 
 		void DrawBezier(Color color, Point pt1, Point pt2, Point pt3, Point pt4);
diff --git a/src/BizHawk.Bizware.Graphics/Renderers/ImGui2DRenderer.cs b/src/BizHawk.Bizware.Graphics/Renderers/ImGui2DRenderer.cs
index afe48c4c14b..394d293d4ca 100644
--- a/src/BizHawk.Bizware.Graphics/Renderers/ImGui2DRenderer.cs
+++ b/src/BizHawk.Bizware.Graphics/Renderers/ImGui2DRenderer.cs
@@ -302,6 +302,9 @@ public void Clear()
 			_hasClearPending = true;
 		}
 
+		public void Discard()
+			=> ResetDrawList();
+
 		protected bool EnableBlending { get; private set; }
 		private bool _pendingBlendEnable;
 
diff --git a/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs b/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs
index a1c4aa63c2a..113cfcce531 100644
--- a/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs
+++ b/src/BizHawk.Client.Common/Api/Classes/EmuClientApi.cs
@@ -90,7 +90,7 @@ public void Dispose()
 
 		public void DoFrameAdvance()
 		{
-			_mainForm.FrameAdvance();
+			_mainForm.FrameAdvance(discardApiHawkSurfaces: false); // we're rendering, so we don't want to discard
 			_mainForm.StepRunLoop_Throttle();
 			_mainForm.Render();
 		}
diff --git a/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs b/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs
index caa38a4ba45..566a6fdd93d 100644
--- a/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs
+++ b/src/BizHawk.Client.Common/DisplayManager/DisplayManagerBase.cs
@@ -933,5 +933,13 @@ public void ClearApiHawkSurfaces()
 				renderer.Clear();
 			}
 		}
+
+		public void DiscardApiHawkSurfaces()
+		{
+			foreach (var renderer in _apiHawkIDTo2DRenderer.Values)
+			{
+				renderer.Discard();
+			}
+		}
 	}
 }
diff --git a/src/BizHawk.Client.Common/IMainFormForApi.cs b/src/BizHawk.Client.Common/IMainFormForApi.cs
index 343aeff4ce6..b835fa02ed0 100644
--- a/src/BizHawk.Client.Common/IMainFormForApi.cs
+++ b/src/BizHawk.Client.Common/IMainFormForApi.cs
@@ -52,7 +52,7 @@ public interface IMainFormForApi
 		bool FlushSaveRAM(bool autosave = false);
 
 		/// <remarks>only referenced from <c>EmuClientApi</c></remarks>
-		void FrameAdvance();
+		void FrameAdvance(bool discardApiHawkSurfaces = true);
 
 		void FrameBufferResized();
 
diff --git a/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs b/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs
index dcc52ea5f1f..db3b8031ff8 100644
--- a/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs
+++ b/src/BizHawk.Client.EmuHawk/IMainFormForTools.cs
@@ -56,7 +56,7 @@ public interface IMainFormForTools : IDialogController
 		bool EnsureCoreIsAccurate();
 
 		/// <remarks>only referenced from <see cref="TAStudio"/></remarks>
-		void FrameAdvance();
+		void FrameAdvance(bool discardApiHawkSurfaces = true);
 
 		/// <remarks>only referenced from <see cref="LuaConsole"/></remarks>
 		void FrameBufferResized();
diff --git a/src/BizHawk.Client.EmuHawk/MainForm.cs b/src/BizHawk.Client.EmuHawk/MainForm.cs
index cb3d706d3d7..34e200ccbe3 100644
--- a/src/BizHawk.Client.EmuHawk/MainForm.cs
+++ b/src/BizHawk.Client.EmuHawk/MainForm.cs
@@ -2477,6 +2477,7 @@ private void SaveSlotSelectedMessage()
 		{
 			if (Config.DispSpeedupFeatures == 0)
 			{
+				DisplayManager.DiscardApiHawkSurfaces();
 				return;
 			}
 
@@ -3069,16 +3070,21 @@ private void LoadConfigFile(string iniPath)
 			_throttle.Step(Config, Sound, allowSleep: true, forceFrameSkip: -1);
 		}
 
-		public void FrameAdvance()
+		public void FrameAdvance(bool discardApiHawkSurfaces)
 		{
 			PressFrameAdvance = true;
 			StepRunLoop_Core(true);
+			if (discardApiHawkSurfaces)
+			{
+				DisplayManager.DiscardApiHawkSurfaces();
+			}
 		}
 
 		public void SeekFrameAdvance()
 		{
 			PressFrameAdvance = true;
 			StepRunLoop_Core(true);
+			DisplayManager.DiscardApiHawkSurfaces();
 			PressFrameAdvance = false;
 		}