From 60e82737b98d84f4e0cb04a0b4732eb6aef27b0f Mon Sep 17 00:00:00 2001
From: SASANO Takayoshi <uaa@uaa.org.uk>
Date: Sat, 18 Jan 2020 06:29:49 +0900
Subject: [PATCH] improve refreshing display

Display space character with DCV command to clear screen, but this command is
very slow. I tested filling whole 160x128 area with 8x16 character by DCV16
command, it took 540msec.

This is the worst case, but display refresh period has extended to 600ms
for safety.

To clear screen, use BOXF command instead. And, reduced issuing DCV command.
---
 TFTSurenoo.cpp | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/TFTSurenoo.cpp b/TFTSurenoo.cpp
index d2def43..73972c7 100644
--- a/TFTSurenoo.cpp
+++ b/TFTSurenoo.cpp
@@ -67,7 +67,7 @@ enum LcdColour {
 
 // This module sometimes ignores display command (too busy?),
 // so supress display refresh
-#define REFRESH_PERIOD		250	// msec
+#define REFRESH_PERIOD		600	// msec
 
 #define STR_CRLF		"\x0D\x0A"
 #define STR_DMR			"DMR"
@@ -352,8 +352,6 @@ void CTFTSurenoo::setLineBuffer(char *buf, const char *text, int maxchar)
 
 	for (i = 0; i < maxchar && text[i] != '\0'; i++)
 		buf[i] = text[i];
-	for (; i < maxchar; i++)
-		buf[i] = ' ';
 	buf[i] = '\0';
 
 	m_refresh = true;
@@ -376,6 +374,11 @@ void CTFTSurenoo::refreshDisplay(void)
 {
 	if (!m_refresh) return;
 
+	// clear display
+	::snprintf(m_temp, sizeof(m_temp), "BOXF(%d,%d,%d,%d,%d);",
+		   0, 0, X_WIDTH - 1, Y_WIDTH - 1, BG_COLOUR);
+	m_serial->write((unsigned char*)m_temp, ::strlen(m_temp));
+
 	// mode line
 	::snprintf(m_temp, sizeof(m_temp), "DCV%d(%d,%d,'%s',%d);",
 		   MODE_FONT_SIZE, 0, 0, m_lineBuf, MODE_COLOUR);
@@ -383,10 +386,13 @@ void CTFTSurenoo::refreshDisplay(void)
 
 	// status line
 	for (int i = 0; i < STATUS_LINES; i++) {
+		char *p = m_lineBuf + statusLine_offset(i);
+		if (!::strlen(p)) continue;
+
 		::snprintf(m_temp, sizeof(m_temp), "DCV%d(%d,%d,'%s',%d);",
 			   STATUS_FONT_SIZE, 0,
 			   STATUS_MARGIN + STATUS_FONT_SIZE * i,
-			   m_lineBuf + statusLine_offset(i), FG_COLOUR);
+			   p, FG_COLOUR);
 		m_serial->write((unsigned char*)m_temp, (unsigned int)::strlen(m_temp));
 	}