From d8068b8f7a81270a01f61e1f0d097e13ad12b411 Mon Sep 17 00:00:00 2001
From: "Collin J. Doering" <collin.doering@rekahsoft.ca>
Date: Wed, 28 Oct 2015 04:40:52 -0400
Subject: [PATCH] Completed scrollUp and scrollDown functions

This completes the functions for ANSI escapes. It required the LCD read
functionality from last commit to be efficient (memory wise).

Signed-off-by: Collin J. Doering <collin.doering@rekahsoft.ca>
---
 lcdLib.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/lcdLib.c b/lcdLib.c
index 4155dad..5fee24f 100644
--- a/lcdLib.c
+++ b/lcdLib.c
@@ -784,9 +784,63 @@ void eraseInline(uint8_t n) {
 }
 
 void scrollUp(uint8_t n) {
+#if LCD_NUMBER_OF_LINES == 1
+  clearDisplay();
+#else
+  if (n >= LCD_NUMBER_OF_LINES) {
+    clearDisplay();
+  } else {
+    uint8_t old_row, old_column;
+    getCursorPosition(&old_row, &old_column);
+
+    uint8_t len = (LCD_NUMBER_OF_LINES - n)*LCD_CHARACTERS_PER_LINE + 1;
+    char str[len];
+    readCharsFromLCD(n + 1, 1, LCD_NUMBER_OF_LINES, LCD_CHARACTERS_PER_LINE, str, len);
+    setCursorPosition(1, 1); // returnHome();
+    writeStringToLCD(str);
+
+    // Add n newlines to bottom of screen
+    for (uint8_t i = 0; i < n; i++) {
+      setCursorPosition(LCD_NUMBER_OF_LINES - i, 1);
+      eraseInline(2);
+    }
+
+    setCursorPosition(old_row, old_column);
+  }
+#endif
 }
 
 void scrollDown(uint8_t n) {
+#if LCD_NUMBER_OF_LINES == 1
+  clearDisplay();
+#else
+  if (n >= LCD_NUMBER_OF_LINES) {
+    clearDisplay();
+  } else {
+    uint8_t old_row, old_column;
+    getCursorPosition(&old_row, &old_column);
+
+    uint8_t len = (LCD_NUMBER_OF_LINES - n)*LCD_CHARACTERS_PER_LINE + 1;
+    char str[len];
+    readCharsFromLCD(1, 1, LCD_NUMBER_OF_LINES - n, LCD_CHARACTERS_PER_LINE, str, len);
+
+    for (uint8_t column = n + 1, i = 0; column <= LCD_NUMBER_OF_LINES; column++) {
+      setCursorPosition(column , 1);
+      for (uint8_t row = 1; row <= LCD_CHARACTERS_PER_LINE; row++) {
+        loop_until_LCD_BF_clear();
+        writeCharToLCD_(str[i++]);
+      }
+    }
+
+    // Add n newlines to top of screen
+    for (uint8_t i = 1; i <= n; i++) {
+      setCursorPosition(i, 1);
+      eraseInline(2);
+    }
+
+    setCursorPosition(old_row, old_column);
+  }
+#endif
 }
 
 void saveCursorPosition() {