From ff36b7225cd146b50cb8e4522ad58aa43c6bc153 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 06 Aug 2021 08:25:33 -0400
Subject: tk: Build focus tab index

---
diff --git a/src/tk/box.c b/src/tk/box.c
index 10a4ec3..d13982d 100644
--- a/src/tk/box.c
+++ b/src/tk/box.c
@@ -51,6 +51,14 @@ _mftk_box_layout(struct mftk_widget *w)
 	b->child_y = (b->container_h - w->h) / 2 + b->padding;
 }
 
+static void
+_mftk_box_index(struct mftk_widget *w, struct mftk_window *win)
+{
+	struct mftk_box *b = (struct mftk_box *) w;
+
+	mftk_window_index(win, b->child);
+}
+
 static int
 _mftk_box_event(struct mftk_widget *w, SDL_Event *e, int x, int y)
 {
@@ -122,7 +130,7 @@ mftk_box_new(int container_w, int container_h, int own_w, int own_h,
 	struct mftk_widget *w;
 	struct mftk_box    *b;
 
-	mftk_widget_init(w, b, box);
+	mftk_widget_init_container(w, b, box);
 
 	b->container_w = container_w;
 	b->container_h = container_h;
diff --git a/src/tk/button.c b/src/tk/button.c
index 57e505a..a236dd4 100644
--- a/src/tk/button.c
+++ b/src/tk/button.c
@@ -108,7 +108,7 @@ mftk_button_new(TTF_Font *font, const char *text, SDL_Color *text_color,
 	struct mftk_widget *w;
 	struct mftk_button *b;
 
-	mftk_widget_init(w, b, button);
+	mftk_widget_init_focusable(w, b, button);
 
 	b->label = mftk_label_new(font, text, text_color, renderer);
 	if (b->label == NULL) {
diff --git a/src/tk/check.c b/src/tk/check.c
index 5c73554..a2eadd0 100644
--- a/src/tk/check.c
+++ b/src/tk/check.c
@@ -223,7 +223,7 @@ mftk_check_new(int butn_width, int butn_padding, SDL_Color *butn_color,
 	struct mftk_widget *w;
 	struct mftk_check  *c;
 
-	mftk_widget_init(w, c, check);
+	mftk_widget_init_focusable(w, c, check);
 
 	if (font != NULL && text != NULL && text_color != NULL) {
 		c->label = mftk_label_new(font, text, text_color, renderer);
diff --git a/src/tk/grid.c b/src/tk/grid.c
index 9d12b3c..e34223d 100644
--- a/src/tk/grid.c
+++ b/src/tk/grid.c
@@ -79,6 +79,17 @@ _mftk_grid_layout(struct mftk_widget *w)
 	}
 }
 
+static void
+_mftk_grid_index(struct mftk_widget *w, struct mftk_window *win)
+{
+	struct mftk_grid *g = (struct mftk_grid *) w;
+	int               i;
+
+	for (i = 0; i < g->rows * g->cols; ++i) {
+		mftk_window_index(win, g->children[i]);
+	}
+}
+
 static int
 _mftk_grid_event(struct mftk_widget *w, SDL_Event *e, int x, int y)
 {
@@ -231,7 +242,7 @@ mftk_grid_new_a(int rows, int cols, int row_spacing, int col_spacing,
 	struct mftk_grid   *g;
 	int                 i;
 
-	mftk_widget_init(w, g, grid);
+	mftk_widget_init_container(w, g, grid);
 
 	g->rows_h = calloc(rows, sizeof(*g->rows_h));
 	if (g->rows_h == NULL) {
diff --git a/src/tk/radio.c b/src/tk/radio.c
index 27f7d37..11acbae 100644
--- a/src/tk/radio.c
+++ b/src/tk/radio.c
@@ -107,7 +107,7 @@ mftk_radio_new(int butn_width, int butn_padding, SDL_Color *butn_color,
 	va_list             ap;
 	int                 i;
 
-	mftk_widget_init(w, r, radio);
+	mftk_widget_init_focusable(w, r, radio);
 
 	r->children = calloc(options, sizeof(*r->children));
 	if (r->children == NULL) {
diff --git a/src/tk/text.c b/src/tk/text.c
index 205c8e3..6bac6e7 100644
--- a/src/tk/text.c
+++ b/src/tk/text.c
@@ -171,7 +171,7 @@ mftk_text_new(char min_char, char max_char, size_t len, const char *val,
 	int                 advance;
 	char                ch;
 
-	mftk_widget_init(w, t, text);
+	mftk_widget_init_focusable(w, t, text);
 
 	t->min_char  = min_char;
 	t->max_char  = max_char;
diff --git a/src/tk/widget.c b/src/tk/widget.c
index ea4835e..5c4ae17 100644
--- a/src/tk/widget.c
+++ b/src/tk/widget.c
@@ -60,6 +60,17 @@ mftk_widget_layout(struct mftk_widget *w)
 	w->layout(w);
 }
 
+void
+mftk_widget_index(struct mftk_widget *w, struct mftk_window *win)
+{
+	if (w->role == MFTK_WIDGET_ROLE_CONTAINER) {
+		w->index(w, win);
+	} else if (w->role == MFTK_WIDGET_ROLE_FOCUSABLE) {
+		mftk_window_index(win, w);
+		w->window = win;
+	}
+}
+
 int
 mftk_widget_event(struct mftk_widget *w, SDL_Event *e, int x, int y)
 {
diff --git a/src/tk/widget.h b/src/tk/widget.h
index 64b8b58..83abe0b 100644
--- a/src/tk/widget.h
+++ b/src/tk/widget.h
@@ -23,18 +23,33 @@
 #include <SDL.h>
 #include <stdarg.h>
 
+void
+mftk_window_index(struct mftk_window *win, struct mftk_widget *wid);
+
+enum mftk_widget_role {
+	MFTK_WIDGET_ROLE_NONE,
+	MFTK_WIDGET_ROLE_FOCUSABLE,
+	MFTK_WIDGET_ROLE_CONTAINER
+};
+
 struct mftk_widget {
-	int                  w;
-	int                  h;
-	struct mftk_widget  *container;
-	int                  vis;
-	int                  can_focus;
-	void               (*layout)(struct mftk_widget *);
-	int                (*event)(struct mftk_widget *, SDL_Event *,
+	int                     w;
+	int                     h;
+	struct mftk_widget     *container;
+	int                     vis;
+	void                  (*layout)(struct mftk_widget *);
+	void                  (*index)(struct mftk_widget *,
+			struct mftk_window *);
+	int                   (*event)(struct mftk_widget *, SDL_Event *,
 			int, int);
-	int                (*render)(struct mftk_widget *, SDL_Renderer *,
+	int                   (*render)(struct mftk_widget *, SDL_Renderer *,
 			int, int);
-	void               (*destroy)(struct mftk_widget *);
+	void                  (*destroy)(struct mftk_widget *);
+	enum mftk_widget_role   role;
+	struct mftk_widget     *prev;
+	struct mftk_widget     *next;
+	struct mftk_window     *window;
+	int                     focused;
 };
 
 struct mftk_widget *
@@ -50,6 +65,34 @@ mftk_widget_new(size_t size);
 		w->event   = &_mftk_##name##_event; \
 		w->render  = &_mftk_##name##_render; \
 		w->destroy = &_mftk_##name##_destroy; \
+		w->role = MFTK_WIDGET_ROLE_NONE; \
+		t_w = (struct mftk_##name *) w; \
+	} while (0)
+#define mftk_widget_init_focusable(w, t_w, name) \
+	do { \
+		w = mftk_widget_new(sizeof(struct mftk_##name)); \
+		if (w == NULL) { \
+			return NULL; \
+		}; \
+		w->layout  = &_mftk_##name##_layout; \
+		w->event   = &_mftk_##name##_event; \
+		w->render  = &_mftk_##name##_render; \
+		w->destroy = &_mftk_##name##_destroy; \
+		w->role = MFTK_WIDGET_ROLE_FOCUSABLE; \
+		t_w = (struct mftk_##name *) w; \
+	} while (0)
+#define mftk_widget_init_container(w, t_w, name) \
+	do { \
+		w = mftk_widget_new(sizeof(struct mftk_##name)); \
+		if (w == NULL) { \
+			return NULL; \
+		}; \
+		w->layout  = &_mftk_##name##_layout; \
+		w->index   = &_mftk_##name##_index; \
+		w->event   = &_mftk_##name##_event; \
+		w->render  = &_mftk_##name##_render; \
+		w->destroy = &_mftk_##name##_destroy; \
+		w->role = MFTK_WIDGET_ROLE_CONTAINER; \
 		t_w = (struct mftk_##name *) w; \
 	} while (0)
 
@@ -63,6 +106,9 @@ mftk_widget_get_visible(struct mftk_widget *w)
 void
 mftk_widget_layout(struct mftk_widget *w);
 
+void
+mftk_widget_index(struct mftk_widget *w, struct mftk_window *win);
+
 int
 mftk_widget_event(struct mftk_widget *w, SDL_Event *e, int x, int y);
 
diff --git a/src/tk/window.c b/src/tk/window.c
index 532a2e4..b87e7c0 100644
--- a/src/tk/window.c
+++ b/src/tk/window.c
@@ -26,6 +26,8 @@
 
 struct mftk_window {
 	struct mftk_widget *root;
+	struct mftk_widget *first;
+	struct mftk_widget *focus;
 };
 
 struct mftk_window *
@@ -44,10 +46,31 @@ mftk_window_new(struct mftk_widget *root)
 	w->root = root;
 
 	mftk_widget_layout(w->root);
+	mftk_widget_index(w->root, w);
+	w->focus = w->first;
 
 	return w;
 }
 
+void
+mftk_window_index(struct mftk_window *win, struct mftk_widget *wid)
+{
+	if (win->first == NULL) {
+		win->first = wid;
+		wid->prev = wid;
+		wid->next = wid;
+		return;
+	}
+	/*
+	 * Head: win->first
+	 * Tail: win->first->prev
+	 */
+	wid->prev              = win->first->prev;
+	wid->next              = win->first;
+	win->first->prev->next = wid;
+	win->first->prev       = wid;
+}
+
 int
 mftk_window_event(struct mftk_window *w, SDL_Event *e)
 {
--
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