From ab798b42f8724161619360ac838dd138cbda1cad Mon Sep 17 00:00:00 2001
From: Jonas Fonseca <fonseca@diku.dk>
Date: Fri, 13 Feb 2009 14:38:00 +0100
Subject: [PATCH] Make behavior of horizontal scrolling configurable

Requested by bill lam.
---
 NEWS        |  3 +++
 tig.c       | 43 +++++++++++++++++++++++++++++++++++++++----
 tigrc.5.txt | 16 +++++++++++++++-
 3 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/NEWS b/NEWS
index e52130c..7bd2889 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,9 @@ Improvements:
  - Colors for 256-capable terminals can be specified as colorN.
  - Entering a number in the prompt will jump to that line number.
  - Handle core.worktree by setting GIT_DIR and GIT_WORK_TREE.
+ - Make behavior of horizontal scrolling configurable by setting the
+   'horizontal-scroll' variable to a number or a percentage. Defaults to
+   scrolling 50% of the view width.
 
 Bug fixes:
 
diff --git a/tig.c b/tig.c
index 2b2607b..705e3dd 100644
--- a/tig.c
+++ b/tig.c
@@ -109,7 +109,6 @@ static size_t utf8_length(const char **string, size_t col, int *width, size_t ma
 
 /* The default interval between line numbers. */
 #define NUMBER_INTERVAL	5
-#define SCROLL_INTERVAL	1
 
 #define TAB_SIZE	8
 
@@ -863,6 +862,7 @@ static bool opt_line_graphics		= TRUE;
 static bool opt_rev_graph		= FALSE;
 static bool opt_show_refs		= TRUE;
 static int opt_num_interval		= NUMBER_INTERVAL;
+static double opt_hscroll		= 0.50;
 static int opt_tab_size			= TAB_SIZE;
 static int opt_author_cols		= AUTHOR_COLS-1;
 static char opt_path[SIZEOF_STR]	= "";
@@ -1384,6 +1384,27 @@ static const struct enum_map attr_map[] = {
 
 #define set_attribute(attr, name)	map_enum(attr, attr_map, name)
 
+static int parse_step(double *opt, const char *arg)
+{
+	*opt = atoi(arg);
+	if (!strchr(arg, '%'))
+		return OK;
+
+	/* "Shift down" so 100% and 1 does not conflict. */
+	*opt = (*opt - 1) / 100;
+	if (*opt >= 1.0) {
+		*opt = 0.99;
+		config_msg = "Step value larger than 100%";
+		return ERR;
+	}
+	if (*opt < 0.0) {
+		*opt = 1;
+		config_msg = "Invalid step value";
+		return ERR;
+	}
+	return OK;
+}
+
 static int
 parse_int(int *opt, const char *arg, int min, int max)
 {
@@ -1513,6 +1534,9 @@ option_set_command(int argc, const char *argv[])
 	if (!strcmp(argv[0], "author-width"))
 		return parse_int(&opt_author_cols, argv[2], 0, 1024);
 
+	if (!strcmp(argv[0], "horizontal-scroll"))
+		return parse_step(&opt_hscroll, argv[2]);
+
 	if (!strcmp(argv[0], "tab-size"))
 		return parse_int(&opt_tab_size, argv[2], 1, 1024);
 
@@ -2285,6 +2309,15 @@ goto_view_line(struct view *view, unsigned long offset, unsigned long lineno)
 	return FALSE;
 }
 
+static int
+apply_step(double step, int value)
+{
+	if (step >= 1)
+		return (int) step;
+	value *= step + 0.01;
+	return value ? value : 1;
+}
+
 /* Scrolling backend */
 static void
 do_scroll_view(struct view *view, int lines)
@@ -2346,10 +2379,10 @@ scroll_view(struct view *view, enum request request)
 			report("Cannot scroll beyond the first column");
 			return;
 		}
-		if (view->yoffset <= SCROLL_INTERVAL)
+		if (view->yoffset <= apply_step(opt_hscroll, view->width))
 			view->yoffset = 0;
 		else
-			view->yoffset -= SCROLL_INTERVAL;
+			view->yoffset -= apply_step(opt_hscroll, view->width);
 		redraw_view_from(view, 0);
 		report("");
 		return;
@@ -2358,7 +2391,9 @@ scroll_view(struct view *view, enum request request)
 			report("Cannot scroll beyond the last column");
 			return;
 		}
-		view->yoffset += SCROLL_INTERVAL;
+		view->yoffset += apply_step(opt_hscroll, view->width);
+		if (view->yoffset > view->width)
+			view->yoffset = view->width;
 		redraw_view(view);
 		report("");
 		return;
diff --git a/tigrc.5.txt b/tigrc.5.txt
index d0e8c91..59149ac 100644
--- a/tigrc.5.txt
+++ b/tigrc.5.txt
@@ -51,6 +51,7 @@ set show-refs = yes		# Show references?
 set show-line-numbers = no	# Show line numbers?
 set line-number-interval = 5	# Interval between line numbers
 set commit-encoding = "UTF-8"	# Commit encoding
+set horizontal-scroll = 33%	# Scroll 33% of the view width
 --------------------------------------------------------------------------
 
 Or in the git configuration files:
@@ -63,7 +64,7 @@ Or in the git configuration files:
 	tab-size = 8		# Number of spaces per tab
 --------------------------------------------------------------------------
 
-The type of variables are either bool, int, and string.
+The type of variables are either bool, int, string, or mixed.
 
 Valid bool values::
 
@@ -78,6 +79,11 @@ Valid string values::
 
 	A string of characters. Optionally, use either ' or " as delimiters.
 
+Valid mixed values::
+
+	These values are composites of the above types. The valid values are
+	specified in the description.
+
 Variables
 ~~~~~~~~~
 
@@ -111,6 +117,14 @@ The following variables can be set:
 
 	Number of spaces per tab. The default is 8 spaces.
 
+'horizontal-scroll' (mixed)::
+
+	Interval to scroll horizontally in each step. Can be specified either
+	as the number of columns, e.g. '5', or as a percentage of the view
+	width, e.g. '33%', where the maximum is 100%. For percentages it is
+	always ensured that at least one column is scrolled. The default is to
+	scroll '50%' of the view width.
+
 'commit-encoding' (string)::
 
 	The encoding used for commits. The default is UTF-8. Not this option
-- 
2.32.0.93.g670b81a890