From 61fce2edab50b837533effea490689d037f231c8 Mon Sep 17 00:00:00 2001
From: Nathan Reiner <nathan@nathanreiner.xyz>
Date: Thu, 23 Mar 2023 17:30:23 +0100
Subject: fix scroll

---
 dmenu-wl.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/dmenu-wl.c b/dmenu-wl.c
index 1fb7ef4..ee2b0a7 100644
--- a/dmenu-wl.c
+++ b/dmenu-wl.c
@@ -81,10 +81,12 @@ struct Options {
 	Option *last;
 	Option *first_match;
 	Option *last_match;
+	Option *current;
 	Option *selection;
 } options = { 0 };
 
 /* function definition */
+static void calculate_scroll();
 static void append_match(Option *item, Option **first, Option **last);
 static void generate_matches();
 static void draw_dmenu(Monitor *monitor);
@@ -142,12 +144,27 @@ Monitor *monitors = 0;
 Monitor *active_monitor = 0;
 uint32_t height = 50;
 uint32_t numitems = 0;
-char input_field[MAX_LINE_LENGTH] = { 0 };
+char input_field[MAX_LINE_LENGTH] = "";
 int running = 1;
 
 #include "config.h"
 
 /* function implementations */
+void
+calculate_scroll()
+{
+	unsigned i = 0;
+	Option *match = options.first_match;
+	options.current = match;
+
+	for (; match && match != options.selection; match = match->next_match) {
+		if (i % lines == lines - 1)
+			options.current = match->next_match;
+		++i;
+	}
+}
+
+
 void
 append_match(Option *item, Option **first, Option **last)
 {
@@ -224,7 +241,7 @@ generate_matches()
 void
 draw_dmenu(Monitor *monitor)
 {
-	Option *match = options.first_match;
+	Option *match = options.current;
 	unsigned x = 0;
 	unsigned y = 0;
 
@@ -241,7 +258,7 @@ draw_dmenu(Monitor *monitor)
 
 	y = 2 * borderwidth + fontsize + 2 * padding;
 
-	for (; match; match = match->next_match) {
+	for (; match && y < height; match = match->next_match) {
 		if (match == options.selection)
 			draw_rect(monitor->canvas, 0, y, monitor->width, fontsize + 2 * padding, highlight);
 		y += fontsize + padding;
@@ -418,10 +435,12 @@ handle_keyboard_event()
 			case XKB_KEY_Down:
 				if (options.selection->next_match)
 					options.selection = options.selection->next_match;
+				calculate_scroll();
 				break;
 			case XKB_KEY_Up:
 				if (options.selection->previous_match)
 					options.selection = options.selection->previous_match;
+				calculate_scroll();
 				break;
 			case XKB_KEY_Left:
 				break;
@@ -506,8 +525,9 @@ setup()
 	if (numitems < lines)
 		lines = numitems;
 
-	generate_matches();
 	height = (lines + 1) * (fontsize + padding * 2) + 3 * borderwidth;
+	generate_matches();
+	calculate_scroll();
 
 	client.repeat.timer = timerfd_create(CLOCK_MONOTONIC, 0);
 	client.xkb_context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
-- 
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