Loading maps using libpng instead of SDL_image

Makefile

@@ -22,7 +22,7 @@ RM      := rm -f
 DEBUG   ?= 1
 
 COMMON_CFLAGS  := -std=$(STD) -Werror -Wextra -Wall -MMD -MP -I$(SRC_DIR) `pkg-config --cflags glib-2.0 gio-2.0`
-COMMON_LDFLAGS := -std=$(STD) -lm `pkg-config --libs glib-2.0 gio-2.0 sdl3 sdl3-image`
+COMMON_LDFLAGS := -std=$(STD) -lm `pkg-config --libs glib-2.0 gio-2.0`
 
 ifeq ($(DEBUG),1)
 	COMMON_CFLAGS  += -g -DDEBUG
@@ -31,12 +31,12 @@ else
 	COMMON_CFLAGS  += -O2 -DNDEBUG
 endif
 
+# libpng should be gone from the client after the server is working
+CLIENT_CFLAGS := $(COMMON_CFLAGS) `pkg-config --cflags sdl3 libpng`
+CLIENT_LDFLAGS := $(COMMON_LDFLAGS) `pkg-config --libs sdl3 libpng`
 
-CLIENT_CFLAGS := $(COMMON_CFLAGS) # `pkg-config --cflags sdl3`
+SERVER_CFLAGS := $(COMMON_CFLAGS) `pkg-config --cflags libpng`
-CLIENT_LDFLAGS := $(COMMON_LDFLAGS) # `pkg-config --libs sdl3`
+SERVER_LDFLAGS := $(COMMON_LDFLAGS) `pkg-config --libs libpng`
-
-SERVER_CFLAGS := $(COMMON_CFLAGS)
-SERVER_LDFLAGS := $(COMMON_LDFLAGS)
 
 CLIENT := librefront
 SERVER := librefront-headless

shell.nix

@@ -5,7 +5,7 @@ in
 pkgs.mkShellNoCC {
   packages = with pkgs; [
     sdl3
-    sdl3-image
+    libpng
     glib
 
     gcc

src/client/client.c

@@ -36,7 +36,7 @@ static World *test_world;
 World *
 _make_test_World ()
 {
-  World *self = World_load_from_file ("res/test_map_2.png");
+  World *self = World_load_from_path ("res/test_map_2.png");
 
   /* TODO: add players and so on. That will be in GameState,
      though. Or GameData. */

src/client/gfx_context.c

@@ -55,7 +55,7 @@ GfxContext_render (GfxContext *self)
     {
       SDL_RenderTexture (self->renderer, self->world_texture, NULL, NULL);
     }
-  
+
   SDL_RenderPresent (self->renderer);
 }
 

src/client/gfx_context.h

@@ -41,8 +41,8 @@ typedef struct GfxContext
 } GfxContext;
 
 GfxContext *GfxContext_new ();
-void GfxContext_render (GfxContext *self);
+void GfxContext_render (GfxContext * self);
 void GfxContext_free (GfxContext * self);
 
 void GfxContext_cache_World (GfxContext * self, World * world);
-void GfxContext_update_Players (GfxContext *self, World * world);
+void GfxContext_update_Players (GfxContext * self, World * world);

src/common/world.c

@@ -1,69 +1,113 @@
 #include <common/world.h>
 
-static inline Uint32
+typedef struct
-_surf_pixel (SDL_Surface *surface, int x, int y)
 {
-  int bpp = SDL_BYTESPERPIXEL (surface->format);
+  const guchar *data;
-  Uint8 *p = (Uint8 *) surface->pixels + y * surface->pitch + x * bpp;
+  gsize size;
+  gsize offset;
+} PngBuffer;
 
-  switch (bpp)
+static void
-    {
+glib_png_read (png_structp png_ptr, png_bytep out_bytes, png_size_t len)
-    case 1:
+{
-      return *p;
+  PngBuffer *buf = (PngBuffer *) png_get_io_ptr (png_ptr);
-    case 2:
+  if (buf->offset + len > buf->size)
-      return *(Uint16 *) p;
+    png_error (png_ptr, "Read beyond buffer");
-    case 3:
+
-      if (SDL_BYTEORDER == SDL_BIG_ENDIAN)
+  memcpy (out_bytes, buf->data + buf->offset, len);
-	{
+  buf->offset += len;
-	  return p[0] << 16 | p[1] << 8 | p[2];
-	}
-      else
-	{
-	  return p[0] | p[1] << 8 | p[2] << 16;
-	}
-    case 4:
-      return *(Uint32 *) p;
-    default:
-      return 0;			// shouldn't happen
-    }
 }
 
 World *
-World_load_from_file (const char *path)
+World_load_from_path (const char *path)
 {
+  UNUSED (path);
+
   World *self = g_new0 (World, 1);
   self->buildings = g_array_new (FALSE, FALSE, sizeof (Building *));
 
-  SDL_Surface *surf = IMG_Load (path);
+  char *png_content = NULL;
+  size_t len = 0;
+  GError *err = NULL;
 
-  if (!surf)
+  if (!g_file_get_contents (path, &png_content, &len, &err))
     {
-      g_warning ("Failed to load map from path %s (returning NULL): %s", path,
+      g_critical ("Failed to load map file %s: %s", path, err->message);
-		 SDL_GetError ());
+      g_error_free (err);
       return NULL;
     }
 
-  self->width = surf->w;
+  png_structp png_ptr =
-  self->height = surf->h;
+    png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
-  self->tiles =
+  png_infop info_ptr = png_create_info_struct (png_ptr);
-    g_array_sized_new (FALSE, FALSE, sizeof (MapTile *), surf->w * surf->h);
 
-  SDL_LockSurface (surf);
+  if (!png_ptr || !info_ptr)
-  const SDL_PixelFormatDetails *details =
-    SDL_GetPixelFormatDetails (surf->format);
-
-  for (int y = 0; y < surf->h; ++y)
     {
-      for (int x = 0; x < surf->w; ++x)
+      g_critical ("%s is not a valid PNG file.", path);
+      g_free (png_content);
+      return NULL;
+    }
+
+  if (setjmp (png_jmpbuf (png_ptr)))
+    {
+      g_critical ("Something got fucked up while loading PNG.");
+      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
+      g_free (png_content);
+      return NULL;
+    }
+
+  PngBuffer buf = { (unsigned char *) png_content, len, 0 };
+  png_set_read_fn (png_ptr, &buf, glib_png_read);
+
+  png_read_info (png_ptr, info_ptr);
+
+  self->width = png_get_image_width (png_ptr, info_ptr);
+  self->height = png_get_image_height (png_ptr, info_ptr);
+  self->tiles = g_array_sized_new (FALSE, FALSE, sizeof (MapTile *),
+				   self->width * self->height);
+
+  png_byte color_type = png_get_color_type (png_ptr, info_ptr);
+  png_byte bit_depth = png_get_bit_depth (png_ptr, info_ptr);
+
+  if (bit_depth == 16)
+    png_set_strip_16 (png_ptr);
+  if (color_type == PNG_COLOR_TYPE_PALETTE)
+    png_set_palette_to_rgb (png_ptr);
+  if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+    png_set_expand_gray_1_2_4_to_8 (png_ptr);
+  if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
+    png_set_tRNS_to_alpha (png_ptr);
+  if (color_type == PNG_COLOR_TYPE_RGB ||
+      color_type == PNG_COLOR_TYPE_GRAY ||
+      color_type == PNG_COLOR_TYPE_PALETTE)
+    png_set_filler (png_ptr, 0xFF, PNG_FILLER_AFTER);
+  if (color_type == PNG_COLOR_TYPE_GRAY ||
+      color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+    png_set_gray_to_rgb (png_ptr);
+
+  png_read_update_info (png_ptr, info_ptr);
+
+  int rowbytes = png_get_rowbytes (png_ptr, info_ptr);
+  unsigned char *image_data = g_malloc (rowbytes * self->height);
+  png_bytep *row_pointers = g_new (png_bytep, self->height);
+
+  for (unsigned int y = 0; y < self->height; y++)
+    row_pointers[y] = image_data + y * rowbytes;
+
+  png_read_image (png_ptr, row_pointers);
+
+  for (unsigned int y = 0; y < self->height; ++y)
+    {
+      for (unsigned int x = 0; x < self->width; ++x)
 	{
 	  MapTile *mt = g_new0 (MapTile, 1);
 	  mt->x = x;
 	  mt->y = y;
 
-	  Uint32 pixel = _surf_pixel (surf, x, y);
+	  unsigned char *px = &row_pointers[y][x * 4];
-	  Uint8 r, g, b, a;
+	  unsigned char r = px[0];
-	  /* NULL is a palette, only used in indexed images. */
+	  unsigned char g = px[1];
-	  SDL_GetRGBA (pixel, details, NULL, &r, &g, &b, &a);
+	  unsigned char b = px[2];
 
 	  /* Improved color ranges (handles light blue water better) */
 	  if (b > 120 && (b > g || b > r))
@@ -82,13 +126,15 @@ World_load_from_file (const char *path)
 	      mt->terrain_type = TERRAIN_HILL;
 	    }
 	  /* Thanks, ChatGPT! */
-	  
+
 	  g_array_append_val (self->tiles, mt);
 	}
     }
 
-  SDL_UnlockSurface (surf);
+  png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
-  SDL_DestroySurface (surf);
+  g_free (row_pointers);
+  g_free (image_data);
+  g_free (png_content);
 
   return self;
 }

src/common/world.h

@@ -1,9 +1,9 @@
 #pragma once
 
-#include <SDL3/SDL.h>
-#include <SDL3_image/SDL_image.h>
-
 #include <glib-2.0/glib.h>
+#include <png.h>
+
+#include <common/util.h>
 
 typedef enum TerrainType
 {
@@ -37,5 +37,5 @@ typedef struct Building
   unsigned int (*at_what_cost) (struct Building * self, World * world);
 } Building;
 
-World *World_load_from_file (const char *path);
+World *World_load_from_path (const char *path);
 void World_tick (World * self);