WIP: testing usage of SDL renderer

It does segfault.

src/renderer.c

@@ -33,6 +33,11 @@ struct RenFont {
 
 
 static SDL_Window *window;
+static SDL_Renderer *window_renderer = NULL;
+static SDL_Texture *window_texture = NULL;
+static SDL_Surface *window_surface = NULL;
+static int window_w = -1, window_h = -1;
+
 static FR_Clip_Area clip;
 
 static void* check_alloc(void *ptr) {
@@ -61,6 +66,30 @@ static const char* utf8_to_codepoint(const char *p, unsigned *dst) {
 }
 
 
+static SDL_Surface *get_window_surface(SDL_Window *this_window) {
+  int w, h;
+  // fprintf(stderr, "get_window_surface: %p\n", this_window); fflush(stderr);
+  SDL_GL_GetDrawableSize(this_window, &w, &h);
+  // FIXME: check for errors ?
+  if (window_surface && w == window_w && h == window_h) {
+    fprintf(stderr, "get_window_surface: return current surface: %p\n", window_surface); fflush(stderr);
+    return window_surface;
+  }
+  if (window_surface) {
+    fprintf(stderr, "going to free: %p\n", window_surface); fflush(stderr);
+    SDL_FreeSurface(window_surface);
+  }
+  window_surface = SDL_CreateRGBSurfaceWithFormat(0, w, h, 24, SDL_PIXELFORMAT_BGR24);
+
+  fprintf(stderr, "NEW surface: %p, size: %d %d\n", window_surface, w, h); fflush(stderr);
+
+  window_w = w;
+  window_h = h;
+
+  return window_surface;
+}
+
+
 void ren_cp_replace_init(CPReplaceTable *rep_table) {
   rep_table->size = 0;
   rep_table->replacements = NULL;
@@ -95,18 +124,42 @@ void ren_cp_replace_add(CPReplaceTable *rep_table, const char *src, const char *
 void ren_init(SDL_Window *win) {
   assert(win);
   window = win;
-  SDL_Surface *surf = SDL_GetWindowSurface(window);
+  SDL_Surface *surf = get_window_surface(window); //SDL_GetWindowSurface(window);
+  fprintf(stderr, "New surface %p\n", surf); fflush(stderr);
   ren_set_clip_rect( (RenRect) { 0, 0, surf->w, surf->h } );
 }
 
 
 void ren_update_rects(RenRect *rects, int count) {
+#if 0
   SDL_UpdateWindowSurfaceRects(window, (SDL_Rect*) rects, count);
+#endif
+  fprintf(stderr, "ren_update_rects\n"); fflush(stderr);
   static bool initial_frame = true;
   if (initial_frame) {
     SDL_ShowWindow(window);
     initial_frame = false;
   }
+
+  int w, h;
+  SDL_GL_GetDrawableSize(window, &w, &h);
+
+  if (window_renderer && (w != window_w || h != window_h)) {
+    SDL_DestroyTexture(window_texture);
+    SDL_DestroyRenderer(window_renderer);
+    window_renderer = NULL;
+  }
+
+  if (!window_renderer) {
+    window_renderer = SDL_CreateRenderer(window, -1, 0);
+    // SDL_CreateTextureFromSurface(sdlRenderer, mySurface);
+    window_texture = SDL_CreateTexture(window_renderer, SDL_PIXELFORMAT_BGR24, SDL_TEXTUREACCESS_STREAMING, w, h);
+    fprintf(stderr, "got new renderer and texture: %p %p\n", window_renderer, window_texture); fflush(stderr);
+  }
+  // FIXME: we ignore the rects here.
+  SDL_UpdateTexture(window_texture, NULL, window_surface->pixels, window_w * 3);
+  SDL_RenderCopy(window_renderer, window_texture, NULL, NULL);
+  SDL_RenderPresent(window_renderer);
 }
 
 
@@ -119,7 +172,7 @@ void ren_set_clip_rect(RenRect rect) {
 
 
 void ren_get_size(int *x, int *y) {
-  SDL_Surface *surf = SDL_GetWindowSurface(window);
+  SDL_Surface *surf = get_window_surface(window); //SDL_GetWindowSurface(window);
   *x = surf->w;
   *y = surf->h;
 }
@@ -278,7 +331,10 @@ void ren_draw_rect(RenRect rect, RenColor color) {
   x2 = x2 > clip.right  ? clip.right  : x2;
   y2 = y2 > clip.bottom ? clip.bottom : y2;
 
-  SDL_Surface *surf = SDL_GetWindowSurface(window);
+  // fprintf(stderr, "ren_draw_rect: clipped rect: (%d, %d) (%d, %d)\n", x1, y1, x2, y2);
+
+  // SDL_Surface *surf = SDL_GetWindowSurface(window);
+  SDL_Surface *surf = get_window_surface(window);
   RenColor *d = (RenColor*) surf->pixels;
   d += x1 + y1 * surf->w;
   int dr = surf->w - (x2 - x1);
@@ -290,6 +346,8 @@ void ren_draw_rect(RenRect rect, RenColor color) {
   }
 }
 
+// FIXME: this function is never used
+#if 0
 void ren_draw_image(RenImage *image, RenRect *sub, int x, int y, RenColor color) {
   if (color.a == 0) { return; }
 
@@ -304,7 +362,7 @@ void ren_draw_image(RenImage *image, RenRect *sub, int x, int y, RenColor color)
   }
 
   /* draw */
-  SDL_Surface *surf = SDL_GetWindowSurface(window);
+  SDL_Surface *surf = get_window_surface(window); //SDL_GetWindowSurface(window);
   RenColor *s = image->pixels;
   RenColor *d = (RenColor*) surf->pixels;
   s += sub->x + sub->y * image->width;
@@ -322,6 +380,7 @@ void ren_draw_image(RenImage *image, RenRect *sub, int x, int y, RenColor color)
     s += sr;
   }
 }
+#endif
 
 static int codepoint_replace(CPReplaceTable *rep_table, unsigned *codepoint) {
   for (int i = 0; i < rep_table->size; i++) {
@@ -340,7 +399,7 @@ void ren_draw_text_subpixel(RenFont *font, const char *text, int x_subpixel, int
 {
   const char *p = text;
   unsigned codepoint;
-  SDL_Surface *surf = SDL_GetWindowSurface(window);
+  SDL_Surface *surf = get_window_surface(window); // SDL_GetWindowSurface(window);
   const FR_Color color_fr = { .r = color.r, .g = color.g, .b = color.b };
   while (*p) {
     FR_Color color_rep;