From 7f6e62f77bca73e49dfa260ff7ac75770d1363c8 Mon Sep 17 00:00:00 2001
From: KatolaZ <katolaz@freaknet.org>
Date: Wed, 31 Jul 2019 11:49:06 +0100
Subject: support line-by-line undo in text mode

---
 draw.c     | 7 +++++++
 gramscii.1 | 6 +++---
 gramscii.h | 5 +++--
 lineset.c  | 5 +++++
 4 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/draw.c b/draw.c
index e4c3250..1e73719 100644
--- a/draw.c
+++ b/draw.c
@@ -77,10 +77,13 @@ void get_text(FILE *fc){
 	int orig_x = x;
 
 	redraw();
+	copy_lines_to_ring(y, y, PRV_STATE);
 	while((c=fgetc(fc))!=EOF && c != 27){
 		if(c=='\n'){
 			set_cur(BG);
+			copy_lines_to_ring(y,y, NEW_STATE);
 			y += 1;
+			copy_lines_to_ring(y, y, PRV_STATE);
 			x = orig_x;
 		}
 		else {
@@ -95,6 +98,8 @@ void get_text(FILE *fc){
 		status_bar();
 		show_cursor();
 	}
+	if (modified)
+		copy_lines_to_ring(y, y, NEW_STATE);
 	mode=MOVE;
 }
 
@@ -245,6 +250,7 @@ update_arrow:
 		show_cursor();
 	}
 	if (c == 'a' || c == '\n'){
+		invalidate_undo();
 		draw_arrow(orig_x, orig_y, arrow, arrow_len, FIX);
 		modified = 1;
 	}
@@ -278,6 +284,7 @@ void erase(FILE *fc){
 	int orig_x = x, orig_y = y;
 	status_bar();
 	show_cursor();
+	invalidate_undo();
 	while((c=fgetc(fc))!=EOF && c!=27 && c!= 'x' && c != '\n'){
 		if (!move_around(c, fc)) continue;
 		check_bound();
diff --git a/gramscii.1 b/gramscii.1
index aa88386..f3ec80e 100644
--- a/gramscii.1
+++ b/gramscii.1
@@ -534,10 +534,10 @@ gramscii currently manages only a fixed screen of the same size of the
 screen where it starts from. This will be changed in a future release to
 support scrolling and "virtual" screens of any (reasonable) size.
 .PP
-gramscii currently does
+Undo commands are only available in box, visual (cut, fill), and text
+mode, and for copy/paste operations. gramscii currently does
 .B not
-support "undo" commands for arrow, text, and erase mode. This will be
-added soon.
+support undo commands for arrow and erase mode. This will be fixed soon.
 .SH AUTHORS
 gramscii is written and maintained by Vincenzo "KatolaZ" Nicosia
 <katolaz@freaknet.org>. You can use, copy, modify, and redistribute
diff --git a/gramscii.h b/gramscii.h
index cadde2d..7aa9f62 100644
--- a/gramscii.h
+++ b/gramscii.h
@@ -149,6 +149,8 @@ void get_arrow(FILE *fc);
 void erase(FILE *fc);
 void visual_box(FILE *fc);
 void paste();
+void undo_change();
+void redo_change();
 
 /** file-related functions **/
 void write_file(FILE *fc);
@@ -165,7 +167,6 @@ void ensure_num_lines(lineset_t *ls, int n);
 void yank_region(int x1, int y1, int x2, int y2);
 void paste_region(int x1, int y1);
 void copy_lines_to_ring(int y1, int y2, int which);
-void undo_change();
-void redo_change();
+void invalidate_undo();
 
 #endif
diff --git a/lineset.c b/lineset.c
index 75ae1d3..4b5ad8c 100644
--- a/lineset.c
+++ b/lineset.c
@@ -171,3 +171,8 @@ void copy_lines_to_ring(int y1, int y2, int which){
 	}
 #endif	
 }
+
+void invalidate_undo(){
+	if (undo_lst > undo_cur)
+		undo_lst = undo_cur;
+}
-- 
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