make context menu scrollable

2 files changed, 39 insertions, 6 deletions

diff --git a/src/menu.c b/src/menu.c
index be7595a..73b1dbd 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -23,8 +23,9 @@ menu *create_menu(menu_entry *entries, int count, int x, int y) {
 	menu *m = calloc(1, sizeof(menu));
 	if (!m) panic("out of memory");
 
+	x += 2; y -= 8;
 	m->window = must(SDL_CreatePopupWindow(window,
-		x + 2, y - 8, 0, 0, SDL_WINDOW_POPUP_MENU | SDL_WINDOW_BORDERLESS
+		x, y, 0, 0, SDL_WINDOW_POPUP_MENU | SDL_WINDOW_BORDERLESS
 	));
 	m->renderer = must(SDL_CreateRenderer(m->window, NULL));
 
@@ -33,7 +34,7 @@ menu *create_menu(menu_entry *entries, int count, int x, int y) {
 	m->textures = calloc(count, sizeof(SDL_Texture *));
 	if (!m->textures) panic("out of memory");
 
-	int w = 0, h = 0;
+	int w = MENU_PADDING, h = MENU_PADDING;
 	for (int i = 0; i < count; i++) {
 		SDL_Color color = {0xff, 0xff, 0xff, 0xff};
 		SDL_Surface *text =
@@ -44,7 +45,27 @@ menu *create_menu(menu_entry *entries, int count, int x, int y) {
 		w = SDL_max(w, tw);
 		h += th;
 	}
-	SDL_SetWindowSize(m->window, w + MENU_PADDING * 2, h + MENU_PADDING * 2);
+	w += MENU_PADDING; h += MENU_PADDING;
+	m->height = h;
+
+	int px, py;
+	must(SDL_GetWindowPosition(window, &px, &py));
+	SDL_Rect disp;
+	must(
+		SDL_GetDisplayUsableBounds(SDL_GetDisplayForWindow(m->window), &disp)
+	);
+	if (py + y + h > disp.h) {
+		y = disp.h - h - py;
+		y = SDL_max(y, disp.y - py);
+	}
+	if (px + x + w > disp.w) {
+		x = disp.w - w - px;
+		x = SDL_max(x, disp.x - px);
+	}
+	h = SDL_min(h, disp.h);
+	SDL_WarpMouseInWindow(window, x - 2, y + 8);
+	SDL_SetWindowPosition(m->window, x, y);
+	SDL_SetWindowSize(m->window, w, h);
 	SDL_RaiseWindow(m->window);
 	SDL_SyncWindow(m->window);
 	return m;
@@ -52,6 +73,16 @@ menu *create_menu(menu_entry *entries, int count, int x, int y) {
 
 bool menu_handle_event(menu *m, SDL_Event e) {
 	switch (e.type) {
+	case SDL_EVENT_MOUSE_WHEEL:
+		if (e.wheel.windowID != SDL_GetWindowID(m->window)) {
+			break;
+		}
+		int w, h;
+		SDL_GetWindowSize(m->window, &w, &h);
+		m->scroll += -e.wheel.y * 15;
+		m->scroll = SDL_max(m->scroll, 0);
+		m->scroll = SDL_min(m->scroll, m->height - h);
+		break;
 	case SDL_EVENT_WINDOW_CLOSE_REQUESTED:
 		if (e.window.windowID == SDL_GetWindowID(m->window))
 			return false;
@@ -64,7 +95,7 @@ bool menu_handle_event(menu *m, SDL_Event e) {
 		if (e.button.windowID != SDL_GetWindowID(m->window)) {
 			break;
 		}
-		int option = option_at(m, e.button.x, e.button.y);
+		int option = option_at(m, e.button.x, e.button.y + m->scroll);
 		if (option != -1) {
 			m->entries[option].action(m->entries[option].data);
 			return false;
@@ -87,11 +118,11 @@ void menu_render(menu *m) {
 	SDL_GetMouseState(&mx, &my);
 	int hovered = -1;
 	if (SDL_GetWindowFlags(m->window) & SDL_WINDOW_MOUSE_FOCUS)
-		hovered = option_at(m, mx, my);
+		hovered = option_at(m, mx, my + m->scroll);
 
 	SDL_SetRenderDrawColor(m->renderer, 0x00, 0x00, 0x00, 0xff);
 	SDL_RenderClear(m->renderer);
-	float x = MENU_PADDING, y = MENU_PADDING;
+	float x = MENU_PADDING, y = MENU_PADDING - SDL_floor(m->scroll);
 	for (int i = 0; i < m->count; i++) {
 		SDL_FRect dst;
 		dst.x = x;
diff --git a/src/menu.h b/src/menu.h
index 1c6cbd1..ddc8e42 100644
--- a/src/menu.h
+++ b/src/menu.h
@@ -16,6 +16,8 @@ typedef struct menu {
 	menu_entry *entries;
 	SDL_Texture **textures;
 	int count;
+	float height;
+	float scroll;
 } menu;
 
 menu *create_menu(menu_entry *entries, int count, int x, int y);