From 4490ced4e32f47863539d1d346e1619ba581322b Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Sat, 13 Nov 2021 15:23:43 -0500
Subject: add move_relative

---
 CHANGELOG.md      |  1 +
 examples/basic.rs |  4 ++--
 src/lib.rs        | 25 +++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7a04a0d..a18d37f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Added
 
 * `hard_refresh` to fully redraw the screen
+* `move_relative` to move the cursor relative to its location
 
 ### Changed
 
diff --git a/examples/basic.rs b/examples/basic.rs
index 624292f..dce12cc 100644
--- a/examples/basic.rs
+++ b/examples/basic.rs
@@ -14,7 +14,7 @@ async fn run(
     tm.move_to(8, 8);
     tm.set_fgcolor(textmode::color::GREEN);
     tm.write_str("bar");
-    tm.move_to(11, 11);
+    tm.move_relative(3, 0);
     tm.set_fgcolor(textmode::Color::Default);
     tm.write_str("baz");
     input.read_key().await?;
@@ -47,7 +47,7 @@ fn main() {
     tm.move_to(8, 8);
     tm.set_fgcolor(textmode::color::GREEN);
     tm.write_str("bar");
-    tm.move_to(11, 11);
+    tm.move_relative(3, 0);
     tm.set_fgcolor(textmode::Color::Default);
     tm.write_str("baz");
     input.read_key().unwrap();
diff --git a/src/lib.rs b/src/lib.rs
index 2f3f0c8..67c0676 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -122,6 +122,31 @@ pub trait Textmode: private::Output {
         self.write(b"H");
     }
 
+    fn move_relative(&mut self, row_offset: i16, col_offset: i16) {
+        let abs_row_offset = row_offset.unsigned_abs();
+        let abs_col_offset = col_offset.unsigned_abs();
+        if row_offset > 0 {
+            self.write(b"\x1b[");
+            self.write_u16(abs_row_offset);
+            self.write(b"B")
+        }
+        if row_offset < 0 {
+            self.write(b"\x1b[");
+            self.write_u16(abs_row_offset);
+            self.write(b"A")
+        }
+        if col_offset > 0 {
+            self.write(b"\x1b[");
+            self.write_u16(abs_col_offset);
+            self.write(b"C")
+        }
+        if col_offset < 0 {
+            self.write(b"\x1b[");
+            self.write_u16(abs_col_offset);
+            self.write(b"D")
+        }
+    }
+
     /// Clears the in-memory screen.
     fn clear(&mut self) {
         self.write(b"\x1b[2J");
-- 
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