A way to restart the event handler with a different code

There are scenarios where one would want to inject a keycode into the
event handler chain, restart the processing from scratch, but with a
keycode different than what the lookup would normally yield. For
example, with one-shot modifiers, a feature one may wish is to be able
to turn the one-shotness off, and have them act as normal modifiers.
This is easily done, if we can remove the one-shot markup, and let the
event handler process the resulting code as-is.

This makes that possible: in a custom event handler, just call
handle_key_event() with the first argument set to the desired code, and
the rest left unchanged. This makes it possible to inject events: not
just register keycodes with the HID, but inject synthetic events,
something much more powerful.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

src/Model01.cpp

@@ -107,12 +107,12 @@ void Model01::act_on_matrix_scan() {
 
             uint8_t keynum = (row*8)+(col);
 
-            handle_key_event(row, 7-col,
+            handle_key_event(Key_NoKey, row, 7-col,
                              bitRead(leftHandState.all, keynum),
                              bitRead(previousLeftHandState.all, keynum)
                             );
 
-            handle_key_event(row, (15- col),
+            handle_key_event(Key_NoKey, row, (15- col),
                              bitRead(rightHandState.all, keynum),
                              bitRead(previousRightHandState.all, keynum)
                             );

src/TestMode.cpp

@@ -61,7 +61,7 @@ void TestMode_::TestMatrix () {
 void TestMode_::setup() {
     eventHandlers[0] = handle_key_event_test;
 }
-bool handle_key_event_test(byte row, byte col, uint8_t currentState, uint8_t previousState) {
+bool handle_key_event_test(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState) {
     Serial.write(row);
 }
 

src/TestMode.h

@@ -15,4 +15,4 @@ class TestMode_ {
 
 extern TestMode_ TestMode;
 
-bool handle_key_event_test(byte row, byte col, uint8_t currentState, uint8_t previousState);
+bool handle_key_event_test(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState);

src/hooks.h

@@ -1,10 +1,11 @@
 #pragma once
 
 #include <Arduino.h>
+#include "key_defs.h"
 
 #define HOOK_MAX 64
 
-typedef bool (*custom_handler_t)(byte row, byte col, uint8_t currentState, uint8_t previousState);
+typedef bool (*custom_handler_t)(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState);
 extern custom_handler_t eventHandlers[HOOK_MAX];
 
 void event_handler_hook_add (custom_handler_t hook);

src/key_events.cpp

@@ -49,19 +49,21 @@ Key lookup_key(byte keymap, byte row, byte col) {
     return mappedKey;
 }
 
-void handle_key_event(byte row, byte col, uint8_t currentState, uint8_t previousState) {
+void handle_key_event(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState) {
     for (byte i = 0; eventHandlers[i] != NULL && i < HOOK_MAX; i++) {
         custom_handler_t handler = eventHandlers[i];
-        if ((*handler)(row, col, currentState, previousState))
+        if ((*handler)(mappedKey, row, col, currentState, previousState))
             return;
     }
 }
 
-bool handle_key_event_default(byte row, byte col, uint8_t currentState, uint8_t previousState) {
+bool handle_key_event_default(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState) {
     //for every newly pressed button, figure out what logical key it is and send a key down event
     // for every newly released button, figure out what logical key it is and send a key up event
 
-    Key mappedKey = lookup_key(temporary_keymap, row, col);
+    if (mappedKey.raw == Key_NoKey.raw) {
+      mappedKey = lookup_key(temporary_keymap, row, col);
+    }
     Key baseKey   = lookup_key(primary_keymap, row, col);
 
     if ((baseKey.flags & SWITCH_TO_KEYMAP

src/key_events.h

@@ -16,10 +16,10 @@ extern const Key keymaps[][ROWS][COLS];
 
 // sending events to the computer
 void handle_synthetic_key_event( Key mappedKey, uint8_t currentState, uint8_t previousState);
-void handle_key_event(byte row, byte col, uint8_t currentState, uint8_t previousState);
+void handle_key_event(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState);
 void press_key(Key mappedKey);
 void handle_keymap_key_event(Key keymapEntry, uint8_t currentState, uint8_t previousState);
 void handle_mouse_key_event(Key mappedKey, uint8_t currentState, uint8_t previousState);
-bool handle_key_event_default(byte row, byte col, uint8_t currentState, uint8_t previousState);
+bool handle_key_event_default(Key mappedKey, byte row, byte col, uint8_t currentState, uint8_t previousState);
 
 Key lookup_key(byte keymap, byte row, byte col);