input: don't map wheel events to BTN_{BACK,FORWARD}

BTN_BACK and BTN_FORWARD are separate buttons. The scroll wheel don't
have any button mappings in libinput/wayland, so make up our own
defines.

This allows us to map them in mouse bindings.

Also expose BTN_WHEEL_{LEFT,RIGHT}. These were already defined, and
used, internally, to handle wheel tilt events. With this, they can
also be used in mouse bindings.

Finally, fix encoding used for BTN_{BACK,FORWARD} when sending mouse
button events to the client application. Before this, they were mapped
to buttons 4/5. But, button 4/5 are for the scroll wheel, and as
mentioned above, BTN_{BACK,FORWARD} are not the same as scroll wheel
"buttons".

Closes #1763

CHANGELOG.md

@@ -89,9 +89,19 @@
   and background are the same), the cursor will instead be rendered
   using the default foreground and background colors, inverted
   ([#1761][1761]).
+* Mouse wheel events now generate `BTN_WHEEL_BACK` and
+  `BTN_WHEEL_FORWARD` "button presses", instead of `BTN_BACK` and
+  `BTN_FORWARD`. The default bindings have been updated, and
+  `scrollback-up-mouse`, `scrollback-down-mouse`, `font-increase` and
+  `font-decrease` now use the new button names.
+  
+  This change allow users to separate physical mouse buttons that
+  _also_ generates `BTN_BACK` and `BTN_FORWARD`, from wheel scrolling
+  ([#1763][1763]).
 
 [1701]: https://codeberg.org/dnkl/foot/issues/1701
 [1761]: https://codeberg.org/dnkl/foot/issues/1761
+[1763]: https://codeberg.org/dnkl/foot/issues/1763
 
 
 ### Deprecated
@@ -118,6 +128,8 @@
   foot config has not set any custom cursor colors (i.e. without
   OSC-12, inverted fg/bg would be used).
 * Wrong color used when drawing the unfocused, hollow cursor.
+* Encoding of `BTN_BACK` and `BTN_FORWARD`, when sending a mouse input
+  escape sequence to the terminal application.
 
 [1694]: https://codeberg.org/dnkl/foot/issues/1694
 [1717]: https://codeberg.org/dnkl/foot/issues/1717

config.c

@@ -1686,6 +1686,7 @@ static const struct {
     const char *name;
     int code;
 } button_map[] = {
+    /* System defined */
     {"BTN_LEFT", BTN_LEFT},
     {"BTN_RIGHT", BTN_RIGHT},
     {"BTN_MIDDLE", BTN_MIDDLE},
@@ -1694,6 +1695,12 @@ static const struct {
     {"BTN_FORWARD", BTN_FORWARD},
     {"BTN_BACK", BTN_BACK},
     {"BTN_TASK", BTN_TASK},
+
+    /* Foot custom, to be able to map scroll events to mouse bindings */
+    {"BTN_WHEEL_BACK", BTN_WHEEL_BACK},
+    {"BTN_WHEEL_FORWARD", BTN_WHEEL_FORWARD},
+    {"BTN_WHEEL_LEFT", BTN_WHEEL_LEFT},
+    {"BTN_WHEEL_RIGHT", BTN_WHEEL_RIGHT},
 };
 
 static int
@@ -2989,8 +2996,8 @@ static void
 add_default_mouse_bindings(struct config *conf)
 {
     const struct config_key_binding bindings[] = {
-        {BIND_ACTION_SCROLLBACK_UP_MOUSE, m("none"), {.m = {BTN_BACK, 1}}},
+        {BIND_ACTION_SCROLLBACK_UP_MOUSE, m("none"), {.m = {BTN_WHEEL_BACK, 1}}},
-        {BIND_ACTION_SCROLLBACK_DOWN_MOUSE, m("none"), {.m = {BTN_FORWARD, 1}}},
+        {BIND_ACTION_SCROLLBACK_DOWN_MOUSE, m("none"), {.m = {BTN_WHEEL_FORWARD, 1}}},
         {BIND_ACTION_PRIMARY_PASTE, m("none"), {.m = {BTN_MIDDLE, 1}}},
         {BIND_ACTION_SELECT_BEGIN, m("none"), {.m = {BTN_LEFT, 1}}},
         {BIND_ACTION_SELECT_BEGIN_BLOCK, m(XKB_MOD_NAME_CTRL), {.m = {BTN_LEFT, 1}}},
@@ -3000,8 +3007,8 @@ add_default_mouse_bindings(struct config *conf)
         {BIND_ACTION_SELECT_WORD_WS, m(XKB_MOD_NAME_CTRL), {.m = {BTN_LEFT, 2}}},
         {BIND_ACTION_SELECT_QUOTE, m("none"), {.m = {BTN_LEFT, 3}}},
         {BIND_ACTION_SELECT_ROW, m("none"), {.m = {BTN_LEFT, 4}}},
-        {BIND_ACTION_FONT_SIZE_UP, m("Control"), {.m = {BTN_BACK, 1}}},
+        {BIND_ACTION_FONT_SIZE_UP, m("Control"), {.m = {BTN_WHEEL_BACK, 1}}},
-        {BIND_ACTION_FONT_SIZE_DOWN, m("Control"), {.m = {BTN_FORWARD, 1}}},
+        {BIND_ACTION_FONT_SIZE_DOWN, m("Control"), {.m = {BTN_WHEEL_FORWARD, 1}}},
     };
 
     conf->bindings.mouse.count = ALEN(bindings);

doc/foot.ini.5.scd

@@ -1156,10 +1156,13 @@ The trailing *COUNT* (number of times the button has to be clicked) is
 optional and specifies the click count required to trigger the
 binding. The default if *COUNT* is omitted is _1_.
 
-To map wheel events (i.e. scrolling), use the button names *BTN_BACK*
+To map wheel events (i.e. scrolling), use the button names
-(up) and *BTN_FORWARD* (down). Note that these events never generate a
+*BTN_WHEEL_BACK* (up) and *BTN_WHEEL_FORWARD* (down). Note that these
-*COUNT* larger than 1. That is, *BTN_BACK+2*, for example, will never
+events never generate a *COUNT* larger than 1. That is,
-trigger.
+*BTN_WHEEL_BACK+2*, for example, will never trigger.
+
+Foot also recognizes tiltable wheels; to map these, use
+*BTN_WHEEL_LEFT* and *BTN_WHEEL_RIGHT*.
 
 A modifier+button combination can only be mapped to *one* action. Lets
 say you want to bind *BTN\_MIDDLE* to *fullscreen*. Since
@@ -1187,7 +1190,7 @@ actions listed under *key-bindings* can be used here as well.
 	Alt screen: send fake _KeyUP_ events to the client application, if
 	alternate scroll mode is enabled.
 	
-	Default: _BTN_BACK_
+	Default: _BTN\_WHEEL\_BACK_
 
 *scrollback-down-mouse*
 	Normal screen: scrolls down the contents.
@@ -1195,7 +1198,7 @@ actions listed under *key-bindings* can be used here as well.
 	Alt screen: send fake _KeyDOWN_ events to the client application, if
 	alternate scroll mode is enabled.
 
-	Default: _BTN_FORWARD_
+	Default: _BTN\_WHEEL\_FORWARD_
 
 *select-begin*
 	Begin an interactive selection. The selection is finalized, and
@@ -1269,12 +1272,12 @@ actions listed under *key-bindings* can be used here as well.
 	Pastes from the _primary selection_. Default: _BTN\_MIDDLE_.
 
 *font-increase*
-	Increases the font size by 0.5pt. Default: _Control+BTN\_BACK_
+	Increases the font size by 0.5pt. Default:
-	(also defined in *key-bindings*).
+	_Control+BTN\_WHEEL\_BACK_ (also defined in *key-bindings*).
 
 *font-decrease*
-	Decreases the font size by 0.5pt. Default: _Control+BTN\_FORWARD_
+	Decreases the font size by 0.5pt. Default:
-	(also defined in *key-bindings*).
+	_Control+BTN\_WHEEL\_FORWARD_ (also defined in *key-bindings*).
 
 
 # TWEAK

foot.ini

@@ -213,8 +213,10 @@
 # \x03=Mod4+c  # Map Super+c -> Ctrl+c
 
 [mouse-bindings]
-# scrollback-up-mouse=BTN_BACK
+# scrollback-up-mouse=BTN_WHEEL_BACK
-# scrollback-down-mouse=BTN_FORWARD
+# scrollback-down-mouse=BTN_WHEEL_FORWARD
+# font-increase=Control+BTN_WHEEL_BACK
+# font-decrease=Control+BTN_WHEEL_FORWARD
 # selection-override-modifiers=Shift
 # primary-paste=BTN_MIDDLE
 # select-begin=BTN_LEFT

input.c

@@ -2708,7 +2708,7 @@ mouse_scroll(struct seat *seat, int amount, enum wl_pointer_axis axis)
     xassert(term != NULL);
 
     int button = axis == WL_POINTER_AXIS_VERTICAL_SCROLL
-        ? amount < 0 ? BTN_BACK : BTN_FORWARD
+        ? amount < 0 ? BTN_WHEEL_BACK : BTN_WHEEL_FORWARD
         : amount < 0 ? BTN_WHEEL_LEFT : BTN_WHEEL_RIGHT;
     amount = abs(amount);
 

input.h

@@ -21,6 +21,8 @@
  * Mouse buttons are in the range 0x110 - 0x11f, with joystick defines
  * starting at 0x120.
  */
+#define BTN_WHEEL_BACK 0x11c
+#define BTN_WHEEL_FORWARD 0x11d
 #define BTN_WHEEL_LEFT 0x11e
 #define BTN_WHEEL_RIGHT 0x11f
 

terminal.c

@@ -3192,17 +3192,23 @@ term_kbd_focus_out(struct terminal *term)
 static int
 linux_mouse_button_to_x(int button)
 {
+    /* Note: on X11, scroll events where reported as buttons. Not so
+     * on Wayland. We manually map scroll events to custom "button"
+     * defines (BTN_WHEEL_*).
+     */
     switch (button) {
-    case BTN_LEFT:        return 1;
+    case BTN_LEFT:          return 1;
-    case BTN_MIDDLE:      return 2;
+    case BTN_MIDDLE:        return 2;
-    case BTN_RIGHT:       return 3;
+    case BTN_RIGHT:         return 3;
-    case BTN_BACK:        return 4;
+    case BTN_WHEEL_BACK:    return 4;  /* Foot custom define */
-    case BTN_FORWARD:     return 5;
+    case BTN_WHEEL_FORWARD: return 5;  /* Foot custom define */
-    case BTN_WHEEL_LEFT:  return 6;  /* Foot custom define */
+    case BTN_WHEEL_LEFT:    return 6;  /* Foot custom define */
-    case BTN_WHEEL_RIGHT: return 7;  /* Foot custom define */
+    case BTN_WHEEL_RIGHT:   return 7;  /* Foot custom define */
-    case BTN_SIDE:        return 8;
+    case BTN_SIDE:          return 8;
-    case BTN_EXTRA:       return 9;
+    case BTN_EXTRA:         return 9;
-    case BTN_TASK:        return -1;  /* TODO: ??? */
+    case BTN_FORWARD:       return 10;
+    case BTN_BACK:          return 11;
+    case BTN_TASK:          return 12; /* Guessing... */
 
     default:
         LOG_WARN("unrecognized mouse button: %d (0x%x)", button, button);