config: support scroll-factor

Fixes: issue #846

docs/labwc-config.5.scd

@@ -210,6 +210,9 @@ The rest of this man page describes configuration options.
 *<mouse><doubleClickTime>*
 	Set double click time in milliseconds. Default is 500.
 
+*<mouse><scrollFactor>*
+	Set scroll factor. Default is 1.0.
+
 *<mouse><context name=""><mousebind button="" direction=""><action>*
 	Multiple *<mousebind>* can exist within one *<context>*; and multiple
 	*<action>* can exist within one *<mousebind>*

docs/rc.xml.all

@@ -199,6 +199,7 @@
 
     <!-- time is in ms -->
     <doubleClickTime>500</doubleClickTime>
+    <scrollFactor>1.0</scrollFactor>
 
     <context name="Frame">
       <mousebind button="A-Left" action="Press">

include/config/rcxml.h

@@ -41,6 +41,7 @@ struct rcxml {
 	/* mouse */
 	long doubleclick_time;     /* in ms */
 	struct wl_list mousebinds; /* struct mousebind.link */
+	double scroll_factor;
 
 	/* libinput */
 	struct wl_list libinput_categories;

src/config/rcxml.c

@@ -420,6 +420,8 @@ entry(xmlNode *node, char *nodename, char *content)
 		} else {
 			wlr_log(WLR_ERROR, "invalid doubleClickTime");
 		}
+	} else if (!strcasecmp(nodename, "scrollFactor.mouse")) {
+		rc.scroll_factor = atof(content);
 	} else if (!strcasecmp(nodename, "name.context.mouse")) {
 		current_mouse_context = content;
 		current_mousebind = NULL;
@@ -573,6 +575,7 @@ rcxml_init(void)
 	init_font_defaults(&rc.font_osd);
 
 	rc.doubleclick_time = 500;
+	rc.scroll_factor = 1.0;
 	rc.repeat_rate = 25;
 	rc.repeat_delay = 600;
 	rc.screen_edge_strength = 20;

src/cursor.c

@@ -1054,7 +1054,8 @@ cursor_axis(struct wl_listener *listener, void *data)
 
 		/* Notify the client with pointer focus of the axis event. */
 		wlr_seat_pointer_notify_axis(seat->seat, event->time_msec,
-			event->orientation, event->delta, event->delta_discrete,
+			event->orientation, rc.scroll_factor * event->delta,
+			round(rc.scroll_factor * event->delta_discrete),
 			event->source);
 	}
 }