Revamp gui component

`gui` was tighly coupled to game logic, and could not be extended for
other purposes. Therefore, a generic GUI implementation, loosely
inspired by well-known GUI frameworks such as GTK, is now provided, with
the following properties:

- Does not depend on dynamic or static memory allocation, only automatic
(i.e., stack) memory allocation required.
- Portable among existing implementations.
- Simple to extend.
- Tiny memory footprint.

`gui` is now composed by GUI elements that can be chained to form a tree
structure. This is useful e.g.: to calculate X/Y coordinates for a given
GUI element given its parent(s).

This commit also refactors the older implementation, moving
game-specific logic into `player` and making use of the new component.

6 files changed, 207 insertions, 17 deletions

diff --git a/src/gui/inc/gui.h b/src/gui/inc/gui.h
index 254fd47..ec87f45 100644
--- a/src/gui/inc/gui.h
+++ b/src/gui/inc/gui.h
@@ -1,33 +1,30 @@
 #ifndef GUI_H
 #define GUI_H
 
+#include <camera.h>
 #include <gfx.h>
-#include <human_player.h>
+#include <peripheral.h>
 
 #ifdef __cplusplus
 extern "C"
 {
 #endif
 
-enum
+struct gui_common
 {
-    GUI_BAR_LEFT,
-    GUI_BAR_MID,
-    GUI_BAR_RIGHT,
-    GUI_SELECTION_UP_LEFT,
-    GUI_SELECTION_UP_RIGHT,
-    GUI_SELECTION_MID_VERT,
-    GUI_SELECTION_DOWN_LEFT,
-    GUI_SELECTION_DOWN_RIGHT,
-    GUI_SELECTION_MID,
-
-    MAX_GUI_SPRITES
+    int (*update)(struct gui_common *, const union peripheral *,
+        const struct camera *);
+    int (*render)(const struct gui_common *);
+    short x, y;
+    bool centered;
+    struct gui_common *parent, *child, *sibling;
 };
 
-void gui_update(struct human_player *h);
-int gui_render(const struct human_player *h);
-
-extern struct sprite gui_sprites[MAX_GUI_SPRITES];
+void gui_add_child(struct gui_common *parent, struct gui_common *child);
+void gui_add_sibling(struct gui_common *g, struct gui_common *sibling);
+int gui_update(struct gui_common *g, const union peripheral *p,
+    const struct camera *c);
+int gui_render(const struct gui_common *g);
 
 #ifdef __cplusplus
 }
diff --git a/src/gui/inc/gui/bar.h b/src/gui/inc/gui/bar.h
new file mode 100644
index 0000000..a8000cf
--- /dev/null
+++ b/src/gui/inc/gui/bar.h
@@ -0,0 +1,39 @@
+#ifndef GUI_BAR_H
+#define GUI_BAR_H
+
+#include <gui.h>
+#include <gfx.h>
+#include <util.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+struct gui_bar
+{
+    struct gui_common common;
+};
+
+UTIL_STATIC_ASSERT(!offsetof(struct gui_bar, common),
+    "unexpected offset for struct gui_bar");
+
+void gui_bar_init(struct gui_bar *b);
+
+enum
+{
+    GUI_BAR_LEFT,
+    GUI_BAR_MID,
+    GUI_BAR_RIGHT,
+
+    MAX_GUI_BAR_SPRITES
+};
+
+extern struct sprite gui_bar_sprites[MAX_GUI_BAR_SPRITES];
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GUI_BAR_H */
diff --git a/src/gui/inc/gui/button.h b/src/gui/inc/gui/button.h
new file mode 100644
index 0000000..acfc6c1
--- /dev/null
+++ b/src/gui/inc/gui/button.h
@@ -0,0 +1,44 @@
+#ifndef GUI_BUTTON_H
+#define GUI_BUTTON_H
+
+#include <gfx.h>
+#include <gui.h>
+#include <gui/label.h>
+#include <util.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+struct gui_button
+{
+    struct gui_common common;
+    struct gui_label label;
+    short w;
+    void *arg;
+    void (*on_pressed)(void *);
+};
+
+UTIL_STATIC_ASSERT(!offsetof(struct gui_button, common),
+    "unexpected offset for struct gui_button");
+
+void gui_button_init(struct gui_button *b);
+
+enum
+{
+    GUI_BUTTON_LEFT,
+    GUI_BUTTON_MID,
+    GUI_BUTTON_RIGHT,
+
+    MAX_GUI_BUTTON_SPRITES
+};
+
+extern struct sprite gui_button_sprites[MAX_GUI_BUTTON_SPRITES];
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GUI_BUTTON_H */
diff --git a/src/gui/inc/gui/label.h b/src/gui/inc/gui/label.h
new file mode 100644
index 0000000..7a30624
--- /dev/null
+++ b/src/gui/inc/gui/label.h
@@ -0,0 +1,30 @@
+#ifndef GUI_LABEL_H
+#define GUI_LABEL_H
+
+#include <gui.h>
+#include <font.h>
+#include <util.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+struct gui_label
+{
+    struct gui_common common;
+    enum font font;
+    const char *text;
+};
+
+UTIL_STATIC_ASSERT(!offsetof(struct gui_label, common),
+    "unexpected offset for struct gui_label");
+
+void gui_label_init(struct gui_label *l);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GUI_LABEL_H */
diff --git a/src/gui/inc/gui/progress_bar.h b/src/gui/inc/gui/progress_bar.h
new file mode 100644
index 0000000..4fa5129
--- /dev/null
+++ b/src/gui/inc/gui/progress_bar.h
@@ -0,0 +1,37 @@
+#ifndef GUI_PROGRESS_BAR_H
+#define GUI_PROGRESS_BAR_H
+
+#include <gui.h>
+#include <util.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+enum {GUI_PROGRESS_BAR_MAX = 255};
+
+struct gui_progress_bar
+{
+    struct gui_common common;
+    short w, h;
+    bool stp;
+    unsigned char progress;
+    struct
+    {
+        unsigned char r, g, b;
+    } fg, bg;
+};
+
+UTIL_STATIC_ASSERT(!offsetof(struct gui_progress_bar, common),
+    "unexpected offset for struct gui_progress_bar");
+
+void gui_progress_bar_init(struct gui_progress_bar *pb);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GUI_PROGRESS_BAR_H */
diff --git a/src/gui/inc/gui/rounded_rect.h b/src/gui/inc/gui/rounded_rect.h
new file mode 100644
index 0000000..2d5a273
--- /dev/null
+++ b/src/gui/inc/gui/rounded_rect.h
@@ -0,0 +1,43 @@
+#ifndef GUI_ROUNDED_RECT_H
+#define GUI_ROUNDED_RECT_H
+
+#include <gui.h>
+#include <gfx.h>
+#include <util.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+struct gui_rounded_rect
+{
+    struct gui_common common;
+    unsigned short w, h;
+};
+
+UTIL_STATIC_ASSERT(!offsetof(struct gui_rounded_rect, common),
+    "unexpected offset for struct gui_rounded_rect");
+
+void gui_rounded_rect_init(struct gui_rounded_rect *l);
+
+enum
+{
+    GUI_ROUNDED_RECT_UP_LEFT,
+    GUI_ROUNDED_RECT_UP_RIGHT,
+    GUI_ROUNDED_RECT_MID_VERT,
+    GUI_ROUNDED_RECT_DOWN_LEFT,
+    GUI_ROUNDED_RECT_DOWN_RIGHT,
+    GUI_ROUNDED_RECT_MID,
+
+    MAX_GUI_ROUNDED_RECT_SPRITES
+};
+
+extern struct sprite gui_rounded_rect_sprites[MAX_GUI_ROUNDED_RECT_SPRITES];
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GUI_ROUNDED_RECT_H */