From 1fa5a0269b4ea8c78738372f36028d479f8e997a Mon Sep 17 00:00:00 2001
From: Aritra Sarkar <aritra1911@yahoo.com>
Date: Wed, 17 Nov 2021 15:27:47 +0530
Subject: [PATCH] Restore cursor position

---
 ansilib/inc/ansi/common.h |  2 +-
 ansilib/inc/ansi/cursor.h |  1 +
 ansilib/src/ansi/cursor.c | 22 ++++++++++++++++++++++
 src/main.c                |  9 ++++++++-
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/ansilib/inc/ansi/common.h b/ansilib/inc/ansi/common.h
index f09c11c..b2b3f18 100644
--- a/ansilib/inc/ansi/common.h
+++ b/ansilib/inc/ansi/common.h
@@ -1,6 +1,6 @@
 #ifndef __ANSI_COMMON_H_
 # define __ANSI_COMMON_H_
 
-# define CSI "\x1b["
+# define CSI "\x1b["    /* Control Sequence Introducer */
 
 #endif  /* __ANSI_COMMON_H_ */
diff --git a/ansilib/inc/ansi/cursor.h b/ansilib/inc/ansi/cursor.h
index 489c09c..d9c4a84 100644
--- a/ansilib/inc/ansi/cursor.h
+++ b/ansilib/inc/ansi/cursor.h
@@ -5,6 +5,7 @@
 
 typedef enum { LEFT, DOWN, UP, RIGHT } dir_t;
 
+point_t get_cursor_pos(void);
 void move_cursor(point_t);
 void nudge_cursor(dir_t, uint32_t step);
 
diff --git a/ansilib/src/ansi/cursor.c b/ansilib/src/ansi/cursor.c
index 5c37b1a..78380f6 100644
--- a/ansilib/src/ansi/cursor.c
+++ b/ansilib/src/ansi/cursor.c
@@ -1,10 +1,32 @@
 #include <unistd.h>
 #include <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
 #include <string.h>
 
 #include <ansi/common.h>
 #include <ansi/cursor.h>
 
+point_t get_cursor_pos(void)
+{
+    char buf[16];
+    point_t ret = { 0 };
+
+    /* ESC[6n   request cursor position (reports as ESC[#;#R) */
+
+    write(STDOUT_FILENO, CSI"6n", 4);
+    if ( read(STDIN_FILENO, buf, 16) ) {
+
+        uint32_t line, column;
+        sscanf(buf, CSI"%"PRIu32"i;%"PRIu32"iR", &line, &column);
+
+        ret.x = column;
+        ret.y = line;
+    }
+
+    return ret;
+}
+
 void move_cursor(point_t pos)
 {
     char buf[16];
diff --git a/src/main.c b/src/main.c
index f0d59af..f8be9cc 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4,6 +4,7 @@
 #include <termios.h>
 #include <unistd.h>
 
+#include <ansi/cursor.h>
 #include <graphics/common.h>
 #include <graphics/shapes.h>
 
@@ -68,7 +69,13 @@ int main(void)
      * }
      */
 
-    draw_rectangle((point_t) { 2, 2 }, 32, 16);
+    /* save current cursor position */
+    point_t orig_cursor_pos = get_cursor_pos();
+
+    draw_rectangle((point_t) { 20, 40 }, 32, 16);
+
+    /* Return to the original cursor position */
+    move_cursor(orig_cursor_pos);
 
     while ( 1 ) {
 
-- 
2.45.2