Fix scroll bar when n_items < max

engine/gui.c

@@ -1,5 +1,7 @@
 #include "gui.h"
+#include "raylib.h"
 #include <string.h>
+#include <stdio.h>
 
 #define RAYGUI_MAX_CONTROLS             16      // Maximum number of standard controls
 #define RAYGUI_MAX_PROPS_BASE           16      // Maximum number of standard properties
@@ -633,6 +635,7 @@ float UI_slider(const UIComp_t* comp, const char *textLeft, const char *textRigh
 
 void vert_scrollarea_init(VertScrollArea_t* scroll_area, Rectangle display_area, Vector2 canvas_dims)
 {
+    scroll_area->comp.font = GetFontDefault(); 
     scroll_area->canvas = LoadRenderTexture(canvas_dims.x, canvas_dims.y);
     scroll_area->scroll_pos = canvas_dims.y - display_area.height;
     scroll_area->scroll_bounds = (Vector2){
@@ -661,14 +664,32 @@ void vert_scrollarea_set_item_dims(VertScrollArea_t* scroll_area, unsigned int i
 {
     scroll_area->item_height = item_height;
     scroll_area->item_padding = item_padding;
-    scroll_area->n_items = (scroll_area->canvas.texture.height - scroll_area->item_padding) / (scroll_area->item_height + scroll_area->item_padding);
+    scroll_area->max_items = (scroll_area->canvas.texture.height - scroll_area->item_padding) / (scroll_area->item_height + scroll_area->item_padding);
+}
+
+bool vert_scrollarea_n_items(VertScrollArea_t* scroll_area, unsigned int n_items) {
+    if (n_items >= scroll_area->max_items) return false;
+
+    // Due to OpenGL convention where y is -1 downwards,
+    // The scroll bar is set to decreases the scroll_pos when going down
+    // This value is used as the offset when rendering, which results in correctly
+    // give the illusion of 'scrolling down'
+    // So, adjust the minimum bound which is the height of the items that are not shown
+    scroll_area->n_items = n_items;
+    scroll_area->scroll_bounds.x =
+        (scroll_area->max_items - n_items)* (scroll_area->item_height + scroll_area->item_padding) + scroll_area->item_padding;
+    return true;
 }
 
 void vert_scrollarea_insert_item(VertScrollArea_t* scroll_area, char* str, unsigned int item_idx)
 {
-    if (item_idx >= scroll_area->n_items) return;
+    if (item_idx >= scroll_area->max_items) return;
 
-    DrawText(str, 0, scroll_area->item_padding + (scroll_area->item_height + scroll_area->item_padding) * item_idx, scroll_area->item_height, BLACK);
+    DrawTextEx(
+        scroll_area->comp.font,
+        str,
+        (Vector2){0, scroll_area->item_padding + (scroll_area->item_height + scroll_area->item_padding) * item_idx}
+        , scroll_area->item_height, 0, BLACK);
 }
 
 unsigned int vert_scrollarea_set_pos(VertScrollArea_t* scroll_area, Vector2 pos)
@@ -676,18 +697,22 @@ unsigned int vert_scrollarea_set_pos(VertScrollArea_t* scroll_area, Vector2 pos)
     float x = pos.x - scroll_area->display_area.x;
     float y = pos.y - scroll_area->display_area.y;
 
-    if (x >= scroll_area->display_area.width || x < 0) return scroll_area->n_items;
+    if (x >= scroll_area->display_area.width || x < 0) return scroll_area->max_items;
-    if (y >= scroll_area->display_area.height || y < 0) return scroll_area->n_items;
+    if (y >= scroll_area->display_area.height || y < 0) return scroll_area->max_items;
 
+    // How much have scroll down
+    float canvas_offset = (scroll_area->scroll_bounds.y - scroll_area->scroll_pos);
 
-    scroll_area->curr_selection = (y - scroll_area->item_padding + (scroll_area->scroll_bounds.y - scroll_area->scroll_pos)) / (scroll_area->item_height + scroll_area->item_padding);
+    scroll_area->curr_selection = (y + canvas_offset - scroll_area->item_padding) / (scroll_area->item_height + scroll_area->item_padding);
 
     return scroll_area->curr_selection;
 }
 
 void vert_scrollarea_refocus(VertScrollArea_t* scroll_area)
 {
-    float selection_y = scroll_area->curr_selection * (scroll_area->item_height + scroll_area->item_padding)  + scroll_area->item_padding - (scroll_area->scroll_bounds.y - scroll_area->scroll_pos);
+    float canvas_offset = (scroll_area->scroll_bounds.y - scroll_area->scroll_pos);
+    // Reverse from item selection to y in display area
+    float selection_y = scroll_area->curr_selection * (scroll_area->item_height + scroll_area->item_padding)  + scroll_area->item_padding - canvas_offset;
 
     // Auto adjust scroll based on selection
     if (selection_y < 0)
@@ -717,7 +742,9 @@ void vert_scrollarea_render(VertScrollArea_t* scroll_area)
         scroll_area->display_area.width,
         scroll_area->display_area.height
     };
-    float selection_y = scroll_area->curr_selection * (scroll_area->item_height + scroll_area->item_padding)  + scroll_area->item_padding - (scroll_area->scroll_bounds.y - scroll_area->scroll_pos);
+
+    float canvas_offset = (scroll_area->scroll_bounds.y - scroll_area->scroll_pos);
+    float selection_y = scroll_area->curr_selection * (scroll_area->item_height + scroll_area->item_padding)  + scroll_area->item_padding - canvas_offset;
 
     DrawRectangle(
         scroll_area->display_area.x,

engine/gui.h

@@ -9,6 +9,7 @@ typedef struct UIComp {
     GuiState state;
     float alpha;
     bool pressed;
+    Font font;
 } UIComp_t;
 
 typedef struct VertScrollArea {
@@ -18,12 +19,14 @@ typedef struct VertScrollArea {
     RenderTexture2D canvas; // Complete canvas
     
     unsigned int n_items;
+    unsigned int max_items;
     unsigned int curr_selection;
     unsigned int item_height;
     unsigned int item_padding;
 
     float scroll_pos;
     Vector2 scroll_bounds;
+    
     UIComp_t scroll_bar;
 
 } VertScrollArea_t;
@@ -31,6 +34,7 @@ typedef struct VertScrollArea {
 void init_UI(void);
 void vert_scrollarea_init(VertScrollArea_t* scroll_area, Rectangle display_area, Vector2 canvas_dims);
 void vert_scrollarea_set_item_dims(VertScrollArea_t* scroll_area, unsigned int item_height, unsigned int item_padding);
+bool vert_scrollarea_n_items(VertScrollArea_t* scroll_area, unsigned int n_items);
 void vert_scrollarea_insert_item(VertScrollArea_t* scroll_area, char* str, unsigned int item_idx);
 unsigned int vert_scrollarea_set_pos(VertScrollArea_t* scroll_area, Vector2 pos);
 void vert_scrollarea_refocus(VertScrollArea_t* scroll_area);

scenes/level_select_scene.c

@@ -7,10 +7,10 @@
 static void level_select_render_func(Scene_t* scene)
 {
     LevelSelectSceneData_t* data = &(CONTAINER_OF(scene, LevelSelectScene_t, scene)->data);
-    Sprite_t* spr = get_sprite(&scene->engine->assets, "bunny_spr1");
     Sprite_t* level_board = get_sprite(&scene->engine->assets, "lvl_board");
     Sprite_t* level_select = get_sprite(&scene->engine->assets, "lvl_select");
     Sprite_t* preview = get_sprite(&scene->engine->assets, "lvlprvw");
+    Font* menu_font = get_font(&scene->engine->assets, "MenuFont");
     BeginTextureMode(scene->layers.render_layers[0].layer_tex);
         ClearBackground(BLANK);
         draw_sprite(level_select, 0, (Vector2){0,0},0, false);
@@ -20,13 +20,8 @@ static void level_select_render_func(Scene_t* scene)
             level_select->frame_size.x + (level_board->frame_size.x - preview->frame_size.x) / 2,
             (level_board->frame_size.y - preview->frame_size.y) / 2,
         },0, false);
-        DrawText("Level Select", 10, 10, 40, BLACK);
+        DrawTextEx(*menu_font, "Level Select", (Vector2){60, 20}, 40, 4, BLACK);
         vert_scrollarea_render(&data->scroll_area);
-        draw_sprite(
-            spr, 0, (Vector2){
-                scene->engine->intended_window_size.x / 2,
-                scene->engine->intended_window_size.y / 2,
-            }, 0, false);
     EndTextureMode();
 }
 
@@ -48,7 +43,7 @@ static void level_select_do_action(Scene_t* scene, ActionType_t action, bool pre
         case ACTION_DOWN:
             if (!pressed)
             {
-                if (data->scroll_area.curr_selection < data->scroll_area.n_items - 1)
+                if (data->scroll_area.curr_selection < data->level_pack->n_levels - 1)
                 {
                     data->scroll_area.curr_selection++;
                     vert_scrollarea_refocus(&data->scroll_area);
@@ -69,7 +64,7 @@ static void level_select_do_action(Scene_t* scene, ActionType_t action, bool pre
             {
                 unsigned int prev_sel = data->scroll_area.curr_selection;
                 // TODO: Add scene offset to scroll area calculation
-                if (vert_scrollarea_set_pos(&data->scroll_area, scene->mouse_pos) != data->scroll_area.n_items)
+                if (vert_scrollarea_set_pos(&data->scroll_area, scene->mouse_pos) != data->scroll_area.max_items)
                 {
                     vert_scrollarea_refocus(&data->scroll_area);
                 
@@ -107,10 +102,9 @@ static void level_select_do_action(Scene_t* scene, ActionType_t action, bool pre
     }
 }
 
-#define FONT_SIZE 15
+#define FONT_SIZE 22
 #define TEXT_PADDING 3
-#define DISPLAY_AREA_HEIGHT 400
+#define SCROLL_TOTAL_HEIGHT 800
-#define SCROLL_TOTAL_HEIGHT 400
 void init_level_select_scene(LevelSelectScene_t* scene)
 {
     init_scene(&scene->scene, &level_select_do_action, 0);
@@ -124,26 +118,31 @@ void init_level_select_scene(LevelSelectScene_t* scene)
         }
     );
     scene->scene.bg_colour = BLACK;
-    vert_scrollarea_init(&scene->data.scroll_area, (Rectangle){50, 100, 150, DISPLAY_AREA_HEIGHT - 100}, (Vector2){150, SCROLL_TOTAL_HEIGHT});
+    Sprite_t* level_select = get_sprite(&scene->scene.engine->assets, "lvl_select");
+    vert_scrollarea_init(&scene->data.scroll_area, (Rectangle){50, 75, level_select->frame_size.x * 0.6, level_select->frame_size.y * 3 / 4}, (Vector2){level_select->frame_size.x * 0.6, SCROLL_TOTAL_HEIGHT});
     vert_scrollarea_set_item_dims(&scene->data.scroll_area, FONT_SIZE, TEXT_PADDING);
+    Font* menu_font = get_font(&scene->scene.engine->assets, "MenuFont");
+    if (menu_font != NULL) {
+        scene->data.scroll_area.comp.font = *menu_font; 
+    }
     char buf[32];
     ScrollAreaRenderBegin(&scene->data.scroll_area);
         ClearBackground(BLANK);
         if (scene->data.level_pack != NULL)
         {
-            scene->data.scroll_area.n_items = scene->data.level_pack->n_levels;
+            vert_scrollarea_n_items(&scene->data.scroll_area, scene->data.level_pack->n_levels);
             for (unsigned int i = 0; i < scene->data.level_pack->n_levels; ++i)
             {
                 vert_scrollarea_insert_item(&scene->data.scroll_area, scene->data.level_pack->levels[i].level_name, i);
             }
-            for (unsigned int i = scene->data.level_pack->n_levels; i < scene->data.scroll_area.n_items; ++i)
+            for (unsigned int i = scene->data.level_pack->n_levels; i < scene->data.scroll_area.max_items; ++i)
             {
                 vert_scrollarea_insert_item(&scene->data.scroll_area, "---", i);
             }
         }
         else
         {
-            for (unsigned int i = 0; i < scene->data.scroll_area.n_items; ++i)
+            for (unsigned int i = 0; i < scene->data.scroll_area.max_items; ++i)
             {
                 sprintf(buf, "Level %u", i); 
                 vert_scrollarea_insert_item(&scene->data.scroll_area, buf, i);