config: add tablet button mapping configuration

Co-authored-by: Consolatis <35009135+Consolatis@users.noreply.github.com>

docs/rc.xml.all

@@ -393,6 +393,18 @@
 
   </mouse>
 
+  <!--
+    Tablet buttons emulate regular mouse buttons.
+
+    The tablet *button* can be set to any of [tip|stylus|stylus2|stylus3].
+    Valid *to* mouse buttons are [left|right|middle].
+  -->
+  <tablet>
+    <map button="tip" to="left" />
+    <map button="stylus" to="right" />
+    <map button="stylus2" to="middle" />
+  </tablet>
+
   <!--
     The *category* element can be set to touch, touchpad, non-touch, default or
     the name of a device. You can obtain device names by running *libinput

include/config/rcxml.h

@@ -9,6 +9,7 @@
 #include "common/border.h"
 #include "common/buf.h"
 #include "common/font.h"
+#include "config/tablet.h"
 #include "config/libinput.h"
 #include "resize_indicator.h"
 #include "theme.h"
@@ -80,6 +81,12 @@ struct rcxml {
 	struct wl_list mousebinds; /* struct mousebind.link */
 	double scroll_factor;
 
+	/* graphics tablet */
+	struct tablet_config {
+		uint16_t button_map_count;
+		struct button_map_entry button_map[BUTTON_MAP_MAX];
+	} tablet;
+
 	/* libinput */
 	struct wl_list libinput_categories;
 

include/config/tablet.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef LABWC_TABLET_CONFIG_H
+#define LABWC_TABLET_CONFIG_H
+
+#include <stdint.h>
+
+#define BUTTON_MAP_MAX 16
+struct button_map_entry {
+	uint32_t from;
+	uint32_t to;
+};
+
+uint32_t tablet_button_from_str(const char *button);
+uint32_t mouse_button_from_str(const char *button);
+void tablet_button_mapping_add(uint32_t from, uint32_t to);
+void tablet_load_default_button_mappings(void);
+
+#endif /* LABWC_TABLET_CONFIG_H */

src/config/meson.build

@@ -3,5 +3,6 @@ labwc_sources += files(
   'keybind.c',
   'session.c',
   'mousebind.c',
+  'tablet.c',
   'libinput.c',
 )

src/config/rcxml.c

@@ -23,6 +23,7 @@
 #include "config/keybind.h"
 #include "config/libinput.h"
 #include "config/mousebind.h"
+#include "config/tablet.h"
 #include "config/rcxml.h"
 #include "labwc.h"
 #include "regions.h"
@@ -615,6 +616,8 @@ entry(xmlNode *node, char *nodename, char *content)
 	/* current <theme><font place=""></font></theme> */
 	static enum font_place font_place = FONT_PLACE_NONE;
 
+	static uint32_t button_map_from;
+
 	if (!nodename) {
 		return;
 	}
@@ -683,6 +686,11 @@ entry(xmlNode *node, char *nodename, char *content)
 		return;
 	}
 
+	if (!strcasecmp(nodename, "map.tablet")) {
+		button_map_from = UINT32_MAX;
+		return;
+	}
+
 	/* handle the rest */
 	if (!content) {
 		return;
@@ -818,6 +826,17 @@ entry(xmlNode *node, char *nodename, char *content)
 		} else {
 			wlr_log(WLR_ERROR, "Invalid value for <resize popupShow />");
 		}
+	} else if (!strcasecmp(nodename, "button.map.tablet")) {
+		button_map_from = tablet_button_from_str(content);
+	} else if (!strcasecmp(nodename, "to.map.tablet")) {
+		if (button_map_from != UINT32_MAX) {
+			uint32_t button_map_to = mouse_button_from_str(content);
+			if (button_map_to != UINT32_MAX) {
+				tablet_button_mapping_add(button_map_from, button_map_to);
+			}
+		} else {
+			wlr_log(WLR_ERROR, "Missing 'button' argument for tablet button mapping");
+		}
 	}
 }
 
@@ -977,6 +996,10 @@ rcxml_init(void)
 
 	rc.doubleclick_time = 500;
 	rc.scroll_factor = 1.0;
+
+	rc.tablet.button_map_count = 0;
+	tablet_load_default_button_mappings();
+
 	rc.repeat_rate = 25;
 	rc.repeat_delay = 600;
 	rc.kb_numlock_enable = true;

src/config/tablet.c

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _POSIX_C_SOURCE 200809L
+#include <linux/input-event-codes.h>
+#include <stdint.h>
+#include <strings.h>
+#include <wlr/util/log.h>
+#include "config/tablet.h"
+#include "config/rcxml.h"
+
+uint32_t tablet_button_from_str(const char *button)
+{
+	if (!strcasecmp(button, "Tip")) {
+		return BTN_TOOL_PEN;
+	} else if (!strcasecmp(button, "Stylus")) {
+		return BTN_STYLUS;
+	} else if (!strcasecmp(button, "Stylus2")) {
+		return BTN_STYLUS2;
+	} else if (!strcasecmp(button, "Stylus3")) {
+		return BTN_STYLUS3;
+	}
+	wlr_log(WLR_ERROR, "Invalid value for tablet button: %s", button);
+	return UINT32_MAX;
+}
+
+uint32_t mouse_button_from_str(const char *button)
+{
+	if (!strcasecmp(button, "Left")) {
+		return BTN_LEFT;
+	} else if (!strcasecmp(button, "Right")) {
+		return BTN_RIGHT;
+	} else if (!strcasecmp(button, "Middle")) {
+		return BTN_MIDDLE;
+	}
+	wlr_log(WLR_ERROR, "Invalid value for mouse button: %s", button);
+	return UINT32_MAX;
+}
+
+void tablet_button_mapping_add(uint32_t from, uint32_t to)
+{
+	struct button_map_entry *entry;
+	for (size_t i = 0; i < rc.tablet.button_map_count; i++) {
+		entry = &rc.tablet.button_map[i];
+		if (entry->from == from) {
+			entry->to = to;
+			wlr_log(WLR_INFO, "Overwriting button map for 0x%x with 0x%x", from, to);
+			return;
+		}
+	}
+	if (rc.tablet.button_map_count == BUTTON_MAP_MAX) {
+		wlr_log(WLR_ERROR,
+			"Failed to add button mapping: only supporting up to %u mappings",
+			BUTTON_MAP_MAX);
+		return;
+	}
+	wlr_log(WLR_INFO, "Adding button map for 0x%x with 0x%x", from, to);
+	entry = &rc.tablet.button_map[rc.tablet.button_map_count];
+	entry->from = from;
+	entry->to = to;
+	rc.tablet.button_map_count++;
+}
+
+void tablet_load_default_button_mappings(void)
+{
+	tablet_button_mapping_add(BTN_TOOL_PEN, BTN_LEFT); /* Used for the pen tip */
+	tablet_button_mapping_add(BTN_STYLUS, BTN_RIGHT);
+	tablet_button_mapping_add(BTN_STYLUS2, BTN_MIDDLE);
+}