add EventQueue.store_next() to allow reusing event objects

Author: dhalbert

locale/circuitpython.pot

@@ -949,6 +949,10 @@ msgstr ""
 msgid "Expected a UUID"
 msgstr ""
 
+#: shared-bindings/keypad/EventQueue.c
+msgid "Expected an %q"
+msgstr ""
+
 #: shared-bindings/_bleio/Adapter.c
 msgid "Expected an Address"
 msgstr ""

shared-bindings/keypad/Event.c

@@ -32,7 +32,7 @@
 
 //| class Event:
 //|     """A key transition event."""
-//|     def __init__(self, key_num: int, pressed: bool) -> None:
+//|     def __init__(self, key_num: int=0, pressed: bool=True) -> None:
 //|         """Create a key transition event, which reports a key-pressed or key-released transition.
 //|
 //|         :param int key_num: the key number
@@ -46,8 +46,8 @@ STATIC mp_obj_t keypad_event_make_new(const mp_obj_type_t *type, size_t n_args,
     self->base.type = &keypad_event_type;
     enum { ARG_key_num, ARG_pressed };
     static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_key_num, MP_ARG_REQUIRED | MP_ARG_INT },
-        { MP_QSTR_pressed, MP_ARG_REQUIRED | MP_ARG_BOOL },
+        { MP_QSTR_key_num, MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_pressed, MP_ARG_BOOL, {.u_bool = true} },
     };
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

shared-bindings/keypad/EventQueue.c

@@ -25,6 +25,7 @@
  */
 
 #include "py/runtime.h"
+#include "shared-bindings/keypad/Event.h"
 #include "shared-bindings/keypad/EventQueue.h"
 
 //| class EventQueue:
@@ -54,6 +55,34 @@ STATIC mp_obj_t keypad_eventqueue_next(mp_obj_t self_in) {
 }
 MP_DEFINE_CONST_FUN_OBJ_1(keypad_eventqueue_next_obj, keypad_eventqueue_next);
 
+//|     def store_next(self, Event: event) -> bool:
+//|         """Store the next key transition event in the supplied event, if available,
+//|         and return ``True``.
+//|         If there are no queued events, do not touch ``event`` and return ``False``.
+//|
+//|         The advantage of this method over ``next()`` is that it does not allocate storage.
+//|         Instead you can reuse an existing ``Event`` object.
+//|
+//|         Note that the queue size is limited; see ``max_events`` in the constructor of
+//|         a scanner such as `Keys` or `KeyMatrix`.
+//|         If a new event arrives when the queue is full, the oldest event is discarded.
+//|
+//|         :return ``True`` if an event was available and stored, ``False`` if not.
+//|         :rtype: bool
+//|         """
+//|         ...
+//|
+STATIC mp_obj_t keypad_eventqueue_store_next(mp_obj_t self_in, mp_obj_t event_in) {
+    keypad_eventqueue_obj_t *self = MP_OBJ_TO_PTR(self_in);
+
+    if (!mp_obj_is_type(event_in, &keypad_event_type)) {
+        mp_raise_ValueError_varg(translate("Expected an %q"), MP_QSTR_Event);
+    }
+    keypad_event_obj_t *event = MP_OBJ_TO_PTR(event_in);
+    return mp_obj_new_bool(common_hal_keypad_eventqueue_store_next(self, event));
+}
+MP_DEFINE_CONST_FUN_OBJ_2(keypad_eventqueue_store_next_obj, keypad_eventqueue_store_next);
+
 //|     def clear(self) -> None:
 //|         """Clear any queued key transition events.
 //|         """
@@ -91,8 +120,9 @@ STATIC mp_obj_t keypad_eventqueue_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
 }
 
 STATIC const mp_rom_map_elem_t keypad_eventqueue_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_clear), MP_ROM_PTR(&keypad_eventqueue_clear_obj) },
-    { MP_ROM_QSTR(MP_QSTR_next),  MP_ROM_PTR(&keypad_eventqueue_next_obj) },
+    { MP_ROM_QSTR(MP_QSTR_clear),       MP_ROM_PTR(&keypad_eventqueue_clear_obj) },
+    { MP_ROM_QSTR(MP_QSTR_next),        MP_ROM_PTR(&keypad_eventqueue_next_obj) },
+    { MP_ROM_QSTR(MP_QSTR_store_next),  MP_ROM_PTR(&keypad_eventqueue_store_next_obj) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(keypad_eventqueue_locals_dict, keypad_eventqueue_locals_dict_table);

shared-bindings/keypad/EventQueue.h

@@ -27,8 +27,8 @@
 #ifndef MICROPY_INCLUDED_SHARED_BINDINGS_KEYPAD_EVENTQUEUE_H
 #define MICROPY_INCLUDED_SHARED_BINDINGS_KEYPAD_EVENTQUEUE_H
 
-#include "py/objlist.h"
-#include "shared-module/keypad/Keys.h"
+#include "shared-module/keypad/Event.h"
+#include "shared-module/keypad/EventQueue.h"
 
 extern const mp_obj_type_t keypad_eventqueue_type;
 
@@ -37,5 +37,6 @@ void common_hal_keypad_eventqueue_construct(keypad_eventqueue_obj_t *self, size_
 void common_hal_keypad_eventqueue_clear(keypad_eventqueue_obj_t *self);
 size_t common_hal_keypad_eventqueue_get_length(keypad_eventqueue_obj_t *self);
 mp_obj_t common_hal_keypad_eventqueue_next(keypad_eventqueue_obj_t *self);
+bool common_hal_keypad_eventqueue_store_next(keypad_eventqueue_obj_t *self, keypad_event_obj_t *event);
 
 #endif  // MICROPY_INCLUDED_SHARED_BINDINGS_KEYPAD_EVENTQUEUE_H

shared-module/keypad/EventQueue.c

@@ -49,6 +49,20 @@ mp_obj_t common_hal_keypad_eventqueue_next(keypad_eventqueue_obj_t *self) {
     return MP_OBJ_FROM_PTR(event);
 }
 
+bool common_hal_keypad_eventqueue_store_next(keypad_eventqueue_obj_t *self, keypad_event_obj_t *event) {
+    int encoded_event = ringbuf_get16(&self->encoded_events);
+    if (encoded_event == -1) {
+        return false;
+    }
+
+    // "Construct" using the existing event.
+    common_hal_keypad_event_construct(event, encoded_event & EVENT_KEY_NUM_MASK, encoded_event & EVENT_PRESSED);
+    return true;
+}
+
+
+
+
 void common_hal_keypad_eventqueue_clear(keypad_eventqueue_obj_t *self) {
     ringbuf_clear(&self->encoded_events);
 }