Change mouse buttons to x11 map and libevdev names

This modifies the way mouse bindings are parsed. Instead of adding to
BTN_LEFT, which results in button numbers that may not be expected,
buttons will be parsed in one of the following ways:

1. `button[1-9]` will now map to their x11 equivalents. This is already
the case for bar bindings. This adds support for binding to axis events,
which was not possible in the previous approach.

2. Anything that starts with `BTN_` will be parsed as an event code name
using `libevdev_event_code_from_name`. This allows for any button to be
mapped to instead of limiting usage to the ones near BTN_LEFT. This also
adds a dependency on libevdev, but since libevdev is already a dependency
of libinput, this should be fine. If needed, this option can have dependency
guards added.

Binding changes:
- button1: BTN_LEFT -> BTN_LEFT
- button2: BTN_RIGHT -> BTN_MIDDLE
- button3: BTN_MIDDLE -> BTN_RIGHT
- button4: BTN_SIDE -> SWAY_SCROLL_UP
- button5: BTN_EXTRA -> SWAY_SCROLL_DOWN
- button6: BTN_FORWARD -> SWAY_SCROLL_LEFT
- button7: BTN_BACK -> SWAY_SCROLL_RIGHT
- button8: BTN_TASK -> BTN_SIDE
- button9: BTN_JOYSTICK -> BTN_EXTRA

Since the axis events need to be mapped to an event code, this uses the
following mappings to avoid any conflicts:
- SWAY_SCROLL_UP: KEY_MAX + 1
- SWAY_SCROLL_DOWN: KEY_MAX + 2
- SWAY_SCROLL_LEFT: KEY_MAX + 3
- SWAY_SCROLL_RIGHT: KEY_MAX + 4

1 files changed, 22 insertions, 3 deletions

diff --git a/sway/commands/bind.c b/sway/commands/bind.c
index 01a35cf2..5990166a 100644
--- a/sway/commands/bind.c
+++ b/sway/commands/bind.c
@@ -1,4 +1,5 @@
 #define _POSIX_C_SOURCE 200809L
+#include <libevdev/libevdev.h>
 #ifdef __linux__
 #include <linux/input-event-codes.h>
 #elif __FreeBSD__
@@ -10,6 +11,7 @@
 #include <strings.h>
 #include "sway/commands.h"
 #include "sway/config.h"
+#include "sway/input/cursor.h"
 #include "sway/ipc-server.h"
 #include "list.h"
 #include "log.h"
@@ -102,9 +104,26 @@ static struct cmd_results *identify_key(const char* name, bool first_key,
 
 		// Check for mouse binding
 		uint32_t button = 0;
-		if (strncasecmp(name, "button", strlen("button")) == 0 &&
-				strlen(name) == strlen("button0")) {
-			button = name[strlen("button")] - '1' + BTN_LEFT;
+		if (strncasecmp(name, "button", strlen("button")) == 0) {
+			// Map to x11 mouse buttons
+			button = name[strlen("button")] - '0';
+			if (button < 1 || button > 9 || strlen(name) > strlen("button0")) {
+				return cmd_results_new(CMD_INVALID, "bindsym",
+						"Only buttons 1-9 are supported. For other mouse "
+						"buttons, use the name of the event code.");
+			}
+			uint32_t buttons[] = {BTN_LEFT, BTN_MIDDLE, BTN_RIGHT,
+				SWAY_SCROLL_UP, SWAY_SCROLL_DOWN, SWAY_SCROLL_LEFT,
+				SWAY_SCROLL_RIGHT, BTN_SIDE, BTN_EXTRA};
+			button = buttons[button - 1];
+		} else if (strncmp(name, "BTN_", strlen("BTN_")) == 0) {
+			// Get event code
+			int code = libevdev_event_code_from_name(EV_KEY, name);
+			if (code == -1) {
+				return cmd_results_new(CMD_INVALID, "bindsym",
+						"Invalid event code name %s", name);
+			}
+			button = code;
 		}
 
 		if (*type == BINDING_KEYSYM) {