set bpm with keys, play/pause with center

application.fam

@@ -0,0 +1,12 @@
+App(
+    appid="metronome",
+    name="Metronome",
+    apptype=FlipperAppType.PLUGIN,
+    entry_point="metronome_app",
+    cdefines=["APP_METRONOME"],
+    requires=[
+        "gui",
+    ],
+    stack_size=2 * 1024,
+    order=20,
+)

metronome.c

@@ -0,0 +1,137 @@
+#include <furi.h>
+#include <gui/gui.h>
+#include <input/input.h>
+#include <m-string.h>
+#include <stdlib.h>
+
+const double BPM_STEP_SIZE = 0.5;
+
+typedef enum {
+    EventTypeTick,
+    EventTypeKey,
+} EventType;
+
+typedef struct {
+    EventType type;
+    InputEvent input;
+} PluginEvent;
+
+typedef struct {
+    double bpm;
+    bool playing;
+} MetronomeState;
+
+static void render_callback(Canvas* const canvas, void* ctx) {
+    const MetronomeState* metronome_state = acquire_mutex((ValueMutex*)ctx, 25);
+    if(metronome_state == NULL) {
+        return;
+    }
+    char* play_state;
+    string_t tempStr;
+    string_init(tempStr);
+
+    // border around the edge of the screen
+    canvas_draw_frame(canvas, 0, 0, 128, 64);
+    canvas_set_font(canvas, FontPrimary);
+
+    // draw playing state
+    if (metronome_state->playing) {
+        play_state = "Playing";
+    } else {
+        play_state = "Paused";
+    }
+    canvas_draw_str_aligned(canvas, 5, 10, AlignLeft, AlignBottom, play_state);
+
+    // draw BPM value
+    string_printf(tempStr, "%.2f", metronome_state->bpm);
+    canvas_set_font(canvas, FontBigNumbers);
+    canvas_draw_str_aligned(canvas, 64, 40, AlignCenter, AlignCenter, string_get_cstr(tempStr));
+    string_reset(tempStr);
+
+    string_clear(tempStr);
+    release_mutex((ValueMutex*)ctx, metronome_state);
+}
+
+static void input_callback(InputEvent* input_event, FuriMessageQueue* event_queue) {
+    furi_assert(event_queue);
+
+    PluginEvent event = {.type = EventTypeKey, .input = *input_event};
+    furi_message_queue_put(event_queue, &event, FuriWaitForever);
+}
+
+static void metronome_state_init(MetronomeState* const metronome_state) {
+    metronome_state->bpm = 120.0;
+    metronome_state->playing = false;
+}
+
+int32_t metronome_app() {
+    FuriMessageQueue* event_queue = furi_message_queue_alloc(8, sizeof(PluginEvent));
+
+    MetronomeState* metronome_state = malloc(sizeof(MetronomeState));
+    metronome_state_init(metronome_state);
+
+    ValueMutex state_mutex;
+    if(!init_mutex(&state_mutex, metronome_state, sizeof(MetronomeState))) {
+        FURI_LOG_E("Metronome", "cannot create mutex\r\n");
+        free(metronome_state);
+        return 255;
+    }
+
+    // Set system callbacks
+    ViewPort* view_port = view_port_alloc();
+    view_port_draw_callback_set(view_port, render_callback, &state_mutex);
+    view_port_input_callback_set(view_port, input_callback, event_queue);
+
+    // Open GUI and register view_port
+    Gui* gui = furi_record_open("gui");
+    gui_add_view_port(gui, view_port, GuiLayerFullscreen);
+
+    PluginEvent event;
+    for(bool processing = true; processing;) {
+        FuriStatus event_status = furi_message_queue_get(event_queue, &event, 100);
+
+        MetronomeState* metronome_state = (MetronomeState*)acquire_mutex_block(&state_mutex);
+
+        if(event_status == FuriStatusOk) {
+            // press events
+            if(event.type == EventTypeKey) {
+                if(event.input.type == InputTypePress) {
+                    switch(event.input.key) {
+                    case InputKeyUp:
+                        break;
+                    case InputKeyDown:
+                        break;
+                    case InputKeyRight:
+                        metronome_state->bpm += BPM_STEP_SIZE;
+                        break;
+                    case InputKeyLeft:
+                        metronome_state->bpm -= BPM_STEP_SIZE;
+                        break;
+                    case InputKeyOk:
+                        metronome_state->playing = !metronome_state->playing;
+                        break;
+                    case InputKeyBack:
+                        processing = false;
+                        break;
+                    }
+                }
+            }
+        } else {
+            FURI_LOG_D("Hello_world", "FuriMessageQueue: event timeout");
+            // event timeout
+        }
+
+        view_port_update(view_port);
+        release_mutex(&state_mutex, metronome_state);
+    }
+
+    view_port_enabled_set(view_port, false);
+    gui_remove_view_port(gui, view_port);
+    furi_record_close("gui");
+    view_port_free(view_port);
+    furi_message_queue_free(event_queue);
+    delete_mutex(&state_mutex);
+    free(metronome_state);
+
+    return 0;
+}