[backend] design a little different

src/backend.h

@@ -2,9 +2,12 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdbool.h>
 
 struct rgn;
+struct msgq;
 struct ax_backend;
+struct ax_theme;
 
 extern const char* ax__backend_impl_name;
 
@@ -13,7 +16,20 @@ int ax__backend_new(
     struct ax_backend** out_bac,
     const char** out_err);
 
-void ax__backend_enqueue_font(
-    struct ax_backend* bac,
-    const char* font_path,
-    size_t font_size);
+enum {
+    ax_msg_shutdown_TAG,
+    ax_msg_load_font_TAG,
+};
+
+struct ax_msg_shutdown {};
+
+struct ax_msg_load_font {
+    struct ax_theme* theme;
+    int category;
+};
+
+struct msgq* ax__backend_msgq(struct ax_backend*);
+
+void ax__backend_wait_for_event(struct ax_backend*);
+
+void ax__backend_step(struct ax_backend*, bool* out_shutdown);

src/backend/sdl.c

@@ -1,32 +1,24 @@
 #include "../backend.h"
 #include "../util/region.h"
 #include "../concurrent/msgq.h"
+#include "../ctxt/theme.h"
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_ttf.h>
 
-/* --- Backend data type --- */
+/* -----------------------------------------------------------------------------
+ * Backend type
+ * -------------------------------------------------------------------------- */
 
 const char* ax__backend_impl_name = "SDL";
 
 struct ax_backend {
     struct msgq* mq;
+    bool shutdown;
 };
 
-/* --- Async messages --- */
-
-enum {
-    msg_close_TAG,
-    msg_load_font_TAG,
-};
-
-struct msg_close {};
-
-struct msg_load_font {
-    const char* path;
-    size_t size;
-};
-
-/* --- Functions --- */
+/* -----------------------------------------------------------------------------
+ * Backend functions
+ * -------------------------------------------------------------------------- */
 
 static void backend_cleanup(struct ax_backend* bac);
 
@@ -49,6 +41,7 @@ int ax__backend_new(
     rgn_pin(init_rgn, bac, (void*) backend_cleanup);
 
     bac->mq = msgq_new(init_rgn);
+    bac->shutdown = false;
 
     if (out_bac != NULL) {
         *out_bac = bac;
@@ -64,21 +57,46 @@ fail:
 
 static void backend_cleanup(struct ax_backend* bac)
 {
-    msgq_begin_send_typed(bac->mq, msg_close);
-    msgq_end_send(bac->mq);
-
-    // printf("bye, from SDL\n");
     TTF_Quit();
     SDL_Quit();
 }
 
-void ax__backend_enqueue_font(
-    struct ax_backend* bac,
-    const char* font_path,
-    size_t font_size)
+struct msgq* ax__backend_msgq(struct ax_backend* bac)
 {
-    struct msg_load_font* m = msgq_begin_send_typed(bac->mq, msg_load_font);
-    m->path = rstrdup(&bac->mq->rgn, font_path);
-    m->size = font_size;
-    msgq_end_send(bac->mq);
+    return bac->mq;
+}
+
+void ax__backend_wait_for_event(struct ax_backend* bac)
+{
+    (void) bac;
+}
+
+void ax__backend_step(struct ax_backend* bac, bool* out_shutdown)
+{
+    int type;
+    void* data;
+    msgq_begin_recv(bac->mq);
+    while ((data = msgq_recv1(bac->mq, &type)) != NULL) {
+        switch (type) {
+
+        case ax_msg_shutdown_TAG:
+            bac->shutdown = true;
+            break;
+
+        case ax_msg_load_font_TAG: {
+            struct ax_msg_load_font* m = data;
+            printf("TODO: load font `%s' (size %zu)\n",
+                   m->theme->font_path[m->category],
+                   m->theme->font_size[m->category]);
+            break;
+        }
+
+        default: break;
+        }
+    }
+    msgq_end_recv(bac->mq);
+
+    if (out_shutdown != NULL) {
+        *out_shutdown = bac->shutdown;
+    }
 }