+ made function that are not designed to be shared static

- removed obsolete window_size_delta struct and helper func
- marked on_wheel with attrib unused -> compiler would refuse compilation

SimpleImageViewer.c

@@ -24,17 +24,12 @@ typedef struct Image{
     SDL_Texture* texture;
 } Image;
 
-typedef struct{
+void error_exit(const char* msg){
-    int w;
-    int h;
-} window_size_delta;
-
-static void error_exit(const char* msg){
     printf("%s\n", msg);
     exit(-1);
 }
 
-static void error_continue(const char* msg){
+void error_continue(const char* msg){
     printf("%s\n", msg);
 }
 
@@ -50,7 +45,7 @@ void free_image_pixels_buffer(Image* image){
     image->pixels = NULL;
 }
 
-SDL_Window* create_window(const char* title, int w, int h){
+static SDL_Window* create_window(const char* title, int w, int h){
     const SDL_InitFlags init_flags = SDL_INIT_VIDEO | SDL_INIT_EVENTS;
     const SDL_WindowFlags window_flags =  SDL_WINDOW_BORDERLESS | SDL_WINDOW_RESIZABLE;
 
@@ -79,7 +74,7 @@ SDL_Window* create_window(const char* title, int w, int h){
     return window;
 }
 
-bool populate_image(SDL_Window* window, Image* image){
+static bool populate_image(SDL_Window* window, Image* image){
     SDL_Surface* surface = SDL_GetWindowSurface(window);
     image->surface = SDL_CreateSurface(image->x, image->y, SDL_PIXELFORMAT_RGBA32);
     if(!image->surface) {
@@ -121,7 +116,7 @@ bool populate_image(SDL_Window* window, Image* image){
     return true;
 }
 
-bool draw_image(SDL_Window* window, Image* image, float pixel_size_delta, int image_start_x, int image_start_y){
+static bool draw_image(SDL_Window* window, Image* image, float pixel_size_delta, int image_start_x, int image_start_y){
     SDL_Surface* surface = SDL_GetWindowSurface(window);
     if(!surface){
         error_continue("Failed to get window surface! Cleaning up and exiting...");
@@ -168,15 +163,7 @@ int clamp_low(const int in, const int low){
     return in < low ? low : in;
 }
 
-window_size_delta get_window_size_delta(SDL_Window* window, int new_w, int new_h){
+static __attribute__((unused)) void on_wheel (SDL_Event* event, SDL_Window* window){
-    int last_w, last_h;
-    SDL_GetWindowSize(window, &last_w, &last_h);
-
-    window_size_delta delta = {new_w - last_w, new_h - last_h};
-    return delta;
-}
-
-void on_wheel(SDL_Event* event, SDL_Window* window){
     int last_w, last_h;
     SDL_GetWindowSize(window, &last_w, &last_h);
 
@@ -198,7 +185,7 @@ void on_wheel(SDL_Event* event, SDL_Window* window){
     SDL_SetWindowSize(window, new_w, new_h);
 }
 
-void loop(SDL_Window* window, Image* image){
+static void loop(SDL_Window* window, Image* image){
     bool drag_left_mouse = false;
     bool drag_right_mouse = false;
     int last_pointer_x = 0;