gui: reuse callback data

There is no need to allocate memory for these callbacks for each single
GUI element. Instead, a single, statically-allocated instance can be
shared among all GUI elements of a given type.

src/gui/inc/gui.h

@@ -12,11 +12,15 @@ extern "C"
 
 struct gui_common
 {
-    void (*add_child)(struct gui_common *parent, struct gui_common *child);
-    int (*update)(struct gui_common *, const union peripheral *,
-        const struct camera *);
-    int (*render)(const struct gui_common *);
-    void (*get_dim)(const struct gui_common *, short *w, short *h);
+    const struct gui_common_cb
+    {
+        void (*add_child)(struct gui_common *parent, struct gui_common *child);
+        int (*update)(struct gui_common *, const union peripheral *,
+            const struct camera *);
+        int (*render)(const struct gui_common *);
+        void (*get_dim)(const struct gui_common *, short *w, short *h);
+    } *cb;
+
     short x, y;
     bool hcentered, vcentered;
     struct gui_common *parent, *child, *sibling;

src/gui/src/bar.c

@@ -74,11 +74,16 @@ static int render(const struct gui_common *const g)
 
 void gui_bar_init(struct gui_bar *const b)
 {
+    static const struct gui_common_cb cb =
+    {
+        .render = render
+    };
+
     *b = (const struct gui_bar)
     {
         .common =
         {
-            .render = render
+            .cb = &cb
         }
     };
 }

src/gui/src/button.c

@@ -164,13 +164,18 @@ static void get_dim(const struct gui_common *const g,
 
 void gui_button_init(struct gui_button *const b)
 {
+    static const struct gui_common_cb cb =
+    {
+        .get_dim = get_dim,
+        .update = update,
+        .render = render
+    };
+
     *b = (const struct gui_button)
     {
         .common =
         {
-            .get_dim = get_dim,
-            .update = update,
-            .render = render
+            .cb = &cb
         }
     };
 

src/gui/src/container.c

@@ -4,13 +4,13 @@
 static void add_child(struct gui_common *const parent,
     struct gui_common *const child)
 {
-    if (!child->get_dim)
+    if (!child->cb || !child->cb->get_dim)
         return;
 
     struct gui_container *const c = (struct gui_container *)parent;
     short w, h;
 
-    child->get_dim(child, &w, &h);
+    child->cb->get_dim(child, &w, &h);
 
     switch (c->mode)
     {
@@ -45,12 +45,17 @@ static void get_dim(const struct gui_common *const g,
 
 void gui_container_init(struct gui_container *const c)
 {
+    static const struct gui_common_cb cb =
+    {
+        .add_child = add_child,
+        .get_dim = get_dim
+    };
+
     *c = (const struct gui_container)
     {
         .common =
         {
-            .add_child = add_child,
-            .get_dim = get_dim
+            .cb = &cb
         }
     };
 }

src/gui/src/gui.c

@@ -3,14 +3,14 @@
 static void get_centered(const struct gui_common *const g,
     short *const x, short *const y)
 {
-    if (g->get_dim)
+    if (g->cb && g->cb->get_dim)
     {
         short w, h, pw = 0, ph = 0;
 
         if (g->parent)
         {
-            if (g->parent->get_dim)
-                g->parent->get_dim(g->parent, &pw, &ph);
+            if (g->parent->cb && g->parent->cb->get_dim)
+                g->parent->cb->get_dim(g->parent, &pw, &ph);
         }
         else
         {
@@ -18,7 +18,7 @@ static void get_centered(const struct gui_common *const g,
             ph = screen_h;
         }
 
-        g->get_dim(g, &w, &h);
+        g->cb->get_dim(g, &w, &h);
 
         if (g->hcentered)
             *x += (pw - w) / 2;
@@ -72,14 +72,14 @@ void gui_add_child(struct gui_common *const p,
 
     c->parent = p;
 
-    if (p->add_child)
-        p->add_child(p, c);
+    if (p->cb && p->cb->add_child)
+        p->cb->add_child(p, c);
 }
 
 int gui_update(struct gui_common *const g, const union peripheral *const p,
     const struct camera *const c)
 {
-    if (g->update && g->update(g, p, c))
+    if (g->cb && g->cb->update && g->cb->update(g, p, c))
         return -1;
 
     if (g->child && gui_update(g->child, p, c))
@@ -94,7 +94,7 @@ int gui_update(struct gui_common *const g, const union peripheral *const p,
 
 int gui_render(const struct gui_common *const g)
 {
-    if (g->render && g->render(g))
+    if (g->cb && g->cb->render && g->cb->render(g))
         return -1;
 
     if (g->child && gui_render(g->child))

src/gui/src/label.c

@@ -23,12 +23,17 @@ static void get_dim(const struct gui_common *const g,
 
 void gui_label_init(struct gui_label *const l)
 {
+    static const struct gui_common_cb cb =
+    {
+        .get_dim = get_dim,
+        .render = render
+    };
+
     *l = (const struct gui_label)
     {
         .common =
         {
-            .get_dim = get_dim,
-            .render = render
+            .cb = &cb
         }
     };
 }

src/gui/src/progress_bar.c

@@ -83,11 +83,16 @@ static int render(const struct gui_common *const g)
 
 void gui_progress_bar_init(struct gui_progress_bar *const pb)
 {
+    static const struct gui_common_cb cb =
+    {
+        .render = render
+    };
+
     *pb = (const struct gui_progress_bar)
     {
         .common =
         {
-            .render = render
+            .cb = &cb
         }
     };
 }

src/gui/src/rounded_rect.c

@@ -224,12 +224,17 @@ static void get_dim(const struct gui_common *const g, short *const w,
 
 void gui_rounded_rect_init(struct gui_rounded_rect *const r)
 {
+    static const struct gui_common_cb cb =
+    {
+        .get_dim = get_dim,
+        .render = render
+    };
+
     *r = (const struct gui_rounded_rect)
     {
         .common =
         {
-            .get_dim = get_dim,
-            .render = render
+            .cb = &cb
         }
     };
 }