Support KEYBOARD and CONSUMER modes of HID on Feather M4 Express

kmk/common/abstract/hid.py

@@ -0,0 +1,155 @@
+import logging
+
+from kmk.common.consts import HIDReportTypes
+from kmk.common.event_defs import HID_REPORT_EVENT
+from kmk.common.keycodes import (FIRST_KMK_INTERNAL_KEYCODE, ConsumerKeycode,
+                                 ModifierKeycode)
+
+
+class AbstractHidHelper:
+    REPORT_BYTES = 8
+
+    def __init__(self, store, log_level=logging.NOTSET):
+        self.logger = logging.getLogger(__name__)
+        self.logger.setLevel(log_level)
+
+        self.store = store
+        self.store.subscribe(
+            lambda state, action: self._subscription(state, action),
+        )
+
+        self._evt = bytearray(self.REPORT_BYTES)
+        self.report_device = memoryview(self._evt)[0:1]
+        self.report_device[0] = HIDReportTypes.KEYBOARD
+
+        # Landmine alert for HIDReportTypes.KEYBOARD: byte index 1 of this view
+        # is "reserved" and evidently (mostly?) unused. However, other modes (or
+        # at least consumer, so far) will use this byte, which is the main reason
+        # this view exists. For KEYBOARD, use report_mods and report_non_mods
+        self.report_keys = memoryview(self._evt)[1:]
+
+        self.report_mods = memoryview(self._evt)[1:2]
+        self.report_non_mods = memoryview(self._evt)[3:]
+
+        self.post_init()
+
+    def post_init(self):
+        pass
+
+    def _subscription(self, state, action):
+        if action.type == HID_REPORT_EVENT:
+            self.clear_all()
+
+            consumer_key = None
+            for key in state.keys_pressed:
+                if isinstance(key, ConsumerKeycode):
+                    consumer_key = key
+                    break
+
+            reporting_device = self.report_device[0]
+            needed_reporting_device = HIDReportTypes.KEYBOARD
+
+            if consumer_key:
+                needed_reporting_device = HIDReportTypes.CONSUMER
+
+            if reporting_device != needed_reporting_device:
+                # If we are about to change reporting devices, release
+                # all keys and close our proverbial tab on the existing
+                # device, or keys will get stuck (mostly when releasing
+                # media/consumer keys)
+                self.send()
+
+            self.report_device[0] = needed_reporting_device
+
+            if consumer_key:
+                self.add_key(consumer_key)
+            else:
+                for key in state.keys_pressed:
+                    if key.code >= FIRST_KMK_INTERNAL_KEYCODE:
+                        continue
+
+                    if isinstance(key, ModifierKeycode):
+                        self.add_modifier(key)
+                    else:
+                        self.add_key(key)
+
+                        if key.has_modifiers:
+                            for mod in key.has_modifiers:
+                                self.add_modifier(mod)
+
+            self.send()
+
+    def hid_send(self, evt):
+        raise NotImplementedError('hid_send(evt) must be implemented')
+
+    def send(self):
+        self.logger.debug('Sending HID report: {}'.format(self._evt))
+        self.hid_send(self._evt)
+
+        return self
+
+    def clear_all(self):
+        for idx, _ in enumerate(self.report_keys):
+            self.report_keys[idx] = 0x00
+
+        return self
+
+    def clear_non_modifiers(self):
+        for idx, _ in enumerate(self.report_non_mods):
+            self.report_non_mods[idx] = 0x00
+
+        return self
+
+    def add_modifier(self, modifier):
+        if isinstance(modifier, ModifierKeycode):
+            self.report_mods[0] |= modifier.code
+        else:
+            self.report_mods[0] |= modifier
+
+        return self
+
+    def remove_modifier(self, modifier):
+        if isinstance(modifier, ModifierKeycode):
+            self.report_mods[0] ^= modifier.code
+        else:
+            self.report_mods[0] ^= modifier
+
+        return self
+
+    def add_key(self, key):
+        # Try to find the first empty slot in the key report, and fill it
+        placed = False
+
+        where_to_place = self.report_non_mods
+
+        if self.report_device[0] == HIDReportTypes.CONSUMER:
+            where_to_place = self.report_keys
+
+        for idx, _ in enumerate(where_to_place):
+            if where_to_place[idx] == 0x00:
+                where_to_place[idx] = key.code
+                placed = True
+                break
+
+        if not placed:
+            self.logger.warning('Out of space in HID report, could not add key')
+
+        return self
+
+    def remove_key(self, key):
+        removed = False
+
+        where_to_place = self.report_non_mods
+
+        if self.report_device[0] == HIDReportTypes.CONSUMER:
+            where_to_place = self.report_keys
+
+        for idx, _ in enumerate(where_to_place):
+            if where_to_place[idx] == key.code:
+                where_to_place[idx] = 0x00
+                removed = True
+
+        if not removed:
+            self.logger.warning('Tried to remove key that was not added')
+
+        return self