[hackers] [svkbd][PATCH] allow neutralizing a key modifier by applying the same modifier again

From: Max Schillinger <maxschillinger_AT_web.de>
Date: Sun, 18 Apr 2021 16:26:05 +0200

svkbd allows you to create keys for symbols of the second (=shift) layer by defining them with a modifier included, like:

    { "|", "|", XK_backslash, 1, XK_Shift_L },

This key creates a pipe symbol by sending shift + backslash. But unfortunately, this way you can't emit get the original symbol (backslash) anymore. So you still need a separate key for typing a backslash, wasting precious space on the screen.

The appended patch fixes this by allowing to neutralize the shift by tapping this key with shift. It works both by tapping first shift, then the pipe key on the on-screen keyboard, or by clicking the pipe key with the middle mouse button (assuming XK_Shift_L is set as the button 2 mod).

This way you can create a "flipped" backslash/pipe key:

    { "|", "\\", XK_backslash, 1, XK_Shift_L },

This patch works equally for AltGr symbols in a `de`-based layout. For example:

    { "~", "+", XK_plus, 1, XK_ISO_Level3_Shift },

(In the German QWERTZ layout, you enter "~" with AltGr-"+".)

Best regards,
Max

---
 svkbd.c | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)
diff --git a/svkbd.c b/svkbd.c
index f9b951d..61778c6 100644
--- a/svkbd.c
+++ b/svkbd.c
_AT_@ -198,16 +198,19 @@ buttonpress(XEvent *e)
 	if (!(k = findkey(ev->x, ev->y)))
 		return;
-	if (k->modifier) {
-		mod = k->modifier;
-	} else {
-		for (i = 0; i < LENGTH(buttonmods); i++) {
-			if (ev->button == buttonmods[i].button) {
-				mod = buttonmods[i].mod;
-				break;
-			}
+	for (i = 0; i < LENGTH(buttonmods); i++) {
+		if (ev->button == buttonmods[i].button) {
+			mod = buttonmods[i].mod;
+			break;
 		}
 	}
+
+	if (k->modifier) {
+		if (mod == k->modifier)
+			mod = 0;
+		else
+			mod = k->modifier;
+	}
 	press(k, mod);
 }
_AT_@ -231,7 +234,9 @@ buttonrelease(XEvent *e)
 	if (ev->x < 0 || ev->y < 0) {
 		unpress(NULL, mod);
 	} else if ((k = findkey(ev->x, ev->y))) {
-		if (k->modifier)
+		if (k->modifier == mod)
+			unpress(k, 0);
+		else if (k->modifier)
 			unpress(k, k->modifier);
 		else
 			unpress(k, mod);
_AT_@ -564,6 +569,7 @@ void
 unpress(Key *k, KeySym buttonmod)
 {
 	int i;
+	Bool neutralizebuttonmod = False;
 	if (k != NULL) {
 		switch(k->keysym) {
_AT_@ -589,10 +595,13 @@ unpress(Key *k, KeySym buttonmod)
 		/* simulate the press event, as we postponed it earlier in press() */
 		for (i = 0; i < numkeys; i++) {
 			if (keys[i].pressed && IsModifierKey(keys[i].keysym)) {
-				simulate_keypress(keys[i].keysym);
+				if (keys[i].keysym == buttonmod)
+					neutralizebuttonmod = True;
+				else
+					simulate_keypress(keys[i].keysym);
 			}
 		}
-		if (buttonmod) {
+		if (buttonmod && !neutralizebuttonmod) {
 			simulate_keypress(buttonmod);
 		}
 		simulate_keypress(k->keysym);
_AT_@ -615,14 +624,15 @@ unpress(Key *k, KeySym buttonmod)
 		}
 	}
-	if (buttonmod) {
+	if (buttonmod && !neutralizebuttonmod) {
 		simulate_keyrelease(buttonmod);
 	}
 	if ((k == NULL) || (!IsModifierKey(k->keysym))) {
 		for (i = 0; i < numkeys; i++) {
 			if (keys[i].pressed && IsModifierKey(keys[i].keysym)) {
-				simulate_keyrelease(keys[i].keysym);
+				if (!(keys[i].keysym == buttonmod && neutralizebuttonmod))
+					simulate_keyrelease(keys[i].keysym);
 				keys[i].pressed = 0;
 				drawkey(&keys[i]);
 			}
--
2.25.1

Received on Sun Apr 18 2021 - 16:26:05 CEST