From e0f9754e80109a093dc061c490dd6a055a1d599d Mon Sep 17 00:00:00 2001
From: mjbudd77 <mjbudd77@gmail.com>
Date: Tue, 5 Oct 2021 06:49:16 -0400
Subject: [PATCH] For Qt GUI, implemented a new method of timing frame advance
 hold delay so that the delay time is more constant with changing emulation
 speed.

---
 src/drivers/Qt/ConsoleWindow.cpp |  5 +++++
 src/drivers/Qt/ConsoleWindow.h   |  2 ++
 src/drivers/Qt/input.cpp         |  7 +++++++
 src/fceu.cpp                     | 13 +++++++------
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/drivers/Qt/ConsoleWindow.cpp b/src/drivers/Qt/ConsoleWindow.cpp
index db7016c5..79ecfc76 100644
--- a/src/drivers/Qt/ConsoleWindow.cpp
+++ b/src/drivers/Qt/ConsoleWindow.cpp
@@ -4162,6 +4162,11 @@ void consoleWin_t::loadMostRecentROM(void)
 	fceuWrapperUnLock();
 }
 
+int consoleWin_t::getPeriodicInterval(void)
+{
+	return gameTimer->interval();
+}
+
 void consoleWin_t::transferVideoBuffer(void)
 {
 	if ( nes_shm->blitUpdated )
diff --git a/src/drivers/Qt/ConsoleWindow.h b/src/drivers/Qt/ConsoleWindow.h
index b1829d70..8bbe3391 100644
--- a/src/drivers/Qt/ConsoleWindow.h
+++ b/src/drivers/Qt/ConsoleWindow.h
@@ -175,6 +175,8 @@ class  consoleWin_t : public QMainWindow
 
 		void OpenHelpWindow(std::string subpage = "");
 
+		int  getPeriodicInterval(void);
+
 	protected:
 		consoleMenuBar *menubar;
 
diff --git a/src/drivers/Qt/input.cpp b/src/drivers/Qt/input.cpp
index 2ee910a6..2be5dec0 100644
--- a/src/drivers/Qt/input.cpp
+++ b/src/drivers/Qt/input.cpp
@@ -52,6 +52,7 @@
 int NoWaiting = 0;
 extern Config *g_config;
 extern bool bindSavestate, frameAdvanceLagSkip, lagCounterDisplay;
+unsigned int frameAdvHoldTimer = 0;
 
 /* UsrInputType[] is user-specified.  CurInputType[] is current
         (game loading can override user settings)
@@ -989,10 +990,15 @@ static void KeyboardCommands(void)
 	{
 		if (frameAdvancing == false)
 		{
+			frameAdvHoldTimer = 0;
 			FCEUI_FrameAdvance();
 			frameAdvancing = true;
 			//printf("Frame Advance Start\n");
 		}
+		if ( consoleWindow )
+		{
+			frameAdvHoldTimer += consoleWindow->getPeriodicInterval();
+		}
 	}
 	else
 	{
@@ -1000,6 +1006,7 @@ static void KeyboardCommands(void)
 		{
 			FCEUI_FrameAdvanceEnd();
 			frameAdvancing = false;
+			frameAdvHoldTimer = 0;
 			//printf("Frame Advance End\n");
 		}
 	}
diff --git a/src/fceu.cpp b/src/fceu.cpp
index f3677f95..80498b4a 100644
--- a/src/fceu.cpp
+++ b/src/fceu.cpp
@@ -717,8 +717,7 @@ void UpdateAutosave(void);
 
 
 #ifdef __QT_DRIVER__
-double getFrameRate(void);
-double getBaseFrameRate(void);
+extern unsigned int frameAdvHoldTimer;
 #endif
 
 ///Emulates a single frame.
@@ -733,18 +732,20 @@ void FCEUI_Emulate(uint8 **pXBuf, int32 **SoundBuf, int32 *SoundBufSize, int ski
 	if (frameAdvanceRequested)
 	{
 #ifdef __QT_DRIVER__
-		double baseFrameRatio = getFrameRate() / getBaseFrameRate();
-
-		int32_t frameAdvanceDelayScaled = (int32_t)( (double)frameAdvance_Delay * baseFrameRatio);
+		uint32_t frameAdvanceDelayScaled = frameAdvance_Delay * (PAL ? 20 : 16);
 
 		if ( frameAdvanceDelayScaled < 1 )
 		{
 			frameAdvanceDelayScaled = 1;
 		}
-		if (frameAdvance_Delay_count == 0 || frameAdvance_Delay_count >= frameAdvanceDelayScaled)
+		if ( (frameAdvance_Delay_count == 0) || (frameAdvHoldTimer >= frameAdvanceDelayScaled) )
+		{
 			EmulationPaused = EMULATIONPAUSED_FA;
+		}
 		if (frameAdvance_Delay_count < frameAdvanceDelayScaled)
+		{
 			frameAdvance_Delay_count++;
+		}
 #else
 		if (frameAdvance_Delay_count == 0 || frameAdvance_Delay_count >= frameAdvance_Delay)
 			EmulationPaused = EMULATIONPAUSED_FA;