From 14a1c227e9e214a2b590731bb488b2c9871ad17b Mon Sep 17 00:00:00 2001
From: Rene Stange <rsta2@o2online.de>
Date: Mon, 28 Oct 2024 19:41:19 +0100
Subject: [PATCH] 2dgraphics: Speed up operation

Before a new graphics frame has been prepared in the uncached display
buffer. Now a separate cached buffer is used, which speeds up operation.
The separate buffer is copied to the display buffer in the vertical sync
phase to suppress flickering. Now this class can be used on the
Raspberry Pi 5 too, but without vertical sync support.

Issue #489
---
 README.md          |  2 +-
 lib/2dgraphics.cpp | 26 ++++++++++++++++++++------
 sample/README      |  2 +-
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 1b9b5311a..75dace9b2 100644
--- a/README.md
+++ b/README.md
@@ -119,7 +119,7 @@ Circle supports the following features:
 |                       | (not on Raspberry Pi 4)                             |                |
 |                       | uGUI (by Achim Doebler)                             |                |
 |                       | LVGL (by LVGL Kft)                                  | x              |
-|                       | 2D graphics class in base library                   |                |
+|                       | 2D graphics class in base library                   | x              |
 |                       |                                                     |                |
 | Not supported         | Bluetooth                                           |                |
 
diff --git a/lib/2dgraphics.cpp b/lib/2dgraphics.cpp
index 5ae01af06..2043912ec 100644
--- a/lib/2dgraphics.cpp
+++ b/lib/2dgraphics.cpp
@@ -5,7 +5,7 @@
 //	Copyright (C) 2021  Stephane Damo
 //
 // Circle - A C++ bare metal environment for Raspberry Pi
-// Copyright (C) 2014-2023  R. Stange <rsta2@o2online.de>
+// Copyright (C) 2014-2024  R. Stange <rsta2@o2online.de>
 // 
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -39,6 +39,8 @@ C2DGraphics::C2DGraphics (unsigned nWidth, unsigned nHeight, boolean bVSync, uns
 
 C2DGraphics::~C2DGraphics (void)
 {
+	delete [] m_Buffer;
+
 	if(m_pFrameBuffer)
 	{
 		delete m_pFrameBuffer;
@@ -47,8 +49,12 @@ C2DGraphics::~C2DGraphics (void)
 
 boolean C2DGraphics::Initialize (void)
 {
+#if RASPPI <= 4
 	m_pFrameBuffer = new CBcmFrameBuffer (m_nWidth, m_nHeight, DEPTH, m_nWidth, 2*m_nHeight,
 					      m_nDisplay, TRUE);
+#else
+	m_pFrameBuffer = new CBcmFrameBuffer (m_nWidth, m_nHeight, DEPTH, 0, 0, m_nDisplay, FALSE);
+#endif
 	
 #if DEPTH == 8
 	m_pFrameBuffer->SetPalette (RED_COLOR, RED_COLOR16);
@@ -76,8 +82,13 @@ boolean C2DGraphics::Initialize (void)
 	m_baseBuffer = (TScreenColor *) (uintptr) m_pFrameBuffer->GetBuffer();
 	m_nWidth = m_pFrameBuffer->GetWidth();
 	m_nHeight = m_pFrameBuffer->GetHeight();
-	m_Buffer = m_baseBuffer + m_nWidth * m_nHeight;
-	
+
+	m_Buffer = new TScreenColor[m_nWidth * m_nHeight];
+	if (!m_Buffer)
+	{
+		return FALSE;
+	}
+
 	return TRUE;
 }
 
@@ -89,6 +100,7 @@ boolean C2DGraphics::Resize (unsigned nWidth, unsigned nHeight)
 	m_nWidth = nWidth;
 	m_nHeight = nHeight;
 
+	delete [] m_Buffer;
 	m_Buffer = 0;
 	m_bBufferSwapped = TRUE;
 
@@ -361,15 +373,17 @@ TScreenColor* C2DGraphics::GetBuffer ()
 
 void C2DGraphics::UpdateDisplay()
 {
-	
+#if RASPPI <= 4
 	if(m_bVSync)
 	{
-		m_pFrameBuffer->SetVirtualOffset(0, m_bBufferSwapped ? m_nHeight : 0);
 		m_pFrameBuffer->WaitForVerticalSync();
+		memcpy (m_baseBuffer + m_bBufferSwapped * m_nWidth * m_nHeight, m_Buffer,
+			m_nWidth * m_nHeight * sizeof(TScreenColor));
+		m_pFrameBuffer->SetVirtualOffset(0, m_bBufferSwapped ? m_nHeight : 0);
 		m_bBufferSwapped = !m_bBufferSwapped;
-		m_Buffer = m_baseBuffer + m_bBufferSwapped * m_nWidth * m_nHeight;
 	}
 	else
+#endif
 	{
 		memcpy(m_baseBuffer, m_Buffer, m_nWidth * m_nHeight * sizeof(TScreenColor));
 	}
diff --git a/sample/README b/sample/README
index 2262a68b9..27dee671c 100644
--- a/sample/README
+++ b/sample/README
@@ -39,7 +39,7 @@ SAMPLES
 38-bootloader		HTTP- and TFTP-based bootloader with Web front-end
 39-umsdplugging	[PnP,5]	Plug in and remove USB flash drives, list directory
 40-irqlatency	[PnP]	Displays the maximum measured IRQ latency
-41-screenanimations	2D graphical shapes demo on screen without flickering or screen tearing
+41-screenanimations [5]	2D graphical shapes demo on screen without flickering or screen tearing
 42-soundinput	[5]	I2S or USB to PWM sound data converter and digital sound recorder
 
 Samples marked with [PnP] are enabled for USB plug-and-play.