reduce calls to win-title

rather than calling the script unconditionally per redraw, we now have
a `title_dirty` flag and keep track of when any of the relavent
information changes.

Co-authored-by: Arthur Williams <taaparthur@gmail.com>
Partially fixes: https://github.com/nsxiv/nsxiv/issues/258

commands.c

@@ -63,6 +63,7 @@ bool cg_switch_mode(arg_t _)
 	}
 	close_info();
 	open_info();
+	title_dirty = true;
 	return true;
 }
 

examples/win-title

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 # Example for $XDG_CONFIG_HOME/nsxiv/exec/win-title
-# Called by nsxiv(1) on each redraw.
+# Called by nsxiv(1) whenever any of the relevant information changes.
 # The output is set as nsxiv's window title.
 #
 # Arguments, "Optional" arguments might be empty:

image.c

@@ -546,7 +546,7 @@ static bool img_fit(img_t *img)
 
 	if (ABS(img->zoom - z) > 1.0/MAX(img->w, img->h)) {
 		img->zoom = z;
-		img->dirty = true;
+		img->dirty = title_dirty = true;
 		return true;
 	} else {
 		return false;
@@ -677,8 +677,7 @@ bool img_zoom_to(img_t *img, float z)
 		img->y = y - (y - img->y) * z / img->zoom;
 		img->zoom = z;
 		img->scalemode = SCALE_ZOOM;
-		img->checkpan = true;
+		img->dirty = img->checkpan = title_dirty = true;
-		img->dirty = true;
 		return true;
 	} else {
 		return false;

main.c

@@ -85,6 +85,8 @@ static struct {
 	extcmd_t f;
 } wintitle;
 
+bool title_dirty;
+
 static timeout_t timeouts[] = {
 	{ { 0, 0 }, false, redraw       },
 	{ { 0, 0 }, false, reset_cursor },
@@ -343,6 +345,7 @@ void load_image(int new)
 	close_info();
 	open_info();
 	arl_setup(&arl, files[fileidx].path);
+	title_dirty = true;
 
 	if (img.multi.cnt > 0 && img.multi.animate)
 		set_timeout(animate, img.multi.frames[img.multi.sel].delay, true);
@@ -451,7 +454,10 @@ void redraw(void)
 		tns_render(&tns);
 	}
 	update_info();
-	win_set_title(&win, false);
+	if (title_dirty) {
+		win_set_title(&win, false);
+		title_dirty = false;
+	}
 	win_draw(&win);
 	reset_timeout(redraw);
 	reset_cursor();

nsxiv.1

@@ -426,7 +426,8 @@ Color of the mark foreground. Defaults to window.foreground
 Please see xrdb(1) on how to change them.
 .SH WINDOW TITLE
 The window title can be replaced with the output of a user-provided script,
-which is called by nsxiv whenever there's a redraw. The path of this script is
+which is called by nsxiv whenever any of the relevant information changes.
+The path of this script is
 .I $XDG_CONFIG_HOME/nsxiv/exec/win-title
 and the arguments given to it (where "Optional" arguments might be empty) are:
 .IP $1 4

nsxiv.h

@@ -470,5 +470,6 @@ extern int alternate;
 extern int markcnt;
 extern int markidx;
 extern int prefix;
+extern bool title_dirty;
 
 #endif /* NSXIV_H */

thumbs.c

@@ -459,6 +459,7 @@ void tns_render(tns_t *tns)
 	}
 	tns->dirty = false;
 	tns_highlight(tns, *tns->sel, true);
+	title_dirty = true;
 }
 
 void tns_mark(tns_t *tns, int n, bool mark)
@@ -527,6 +528,7 @@ bool tns_move_selection(tns_t *tns, direction_t dir, int cnt)
 		tns_check_view(tns, false);
 		if (!tns->dirty)
 			tns_highlight(tns, *tns->sel, true);
+		title_dirty = true;
 	}
 	return *tns->sel != old;
 }