Update font scale on monitor scale change for `RENDERER` backend (macOS) (#1650)

* Update font scale on monitor scale change for `RENDERER` backend (macOS)

* fix(renderer): check every font of a fontgroup for scale changes in `update_font_scale`

It is needed because fonts can be reused between groups and outside of them.
So if the first font of a group has already been scaled, we still need to check if the others still needs to be scaled.

src/api/renderer.c

@@ -98,18 +98,24 @@ static int f_font_load(lua_State *L) {
 }
 
 static bool font_retrieve(lua_State* L, RenFont** fonts, int idx) {
+  bool is_table;
   memset(fonts, 0, sizeof(RenFont*)*FONT_FALLBACK_MAX);
   if (lua_type(L, idx) != LUA_TTABLE) {
     fonts[0] = *(RenFont**)luaL_checkudata(L, idx, API_TYPE_FONT);
-    return false;
-  }
+    is_table = false;
+  } else {
+    is_table = true;
     int len = luaL_len(L, idx); len = len > FONT_FALLBACK_MAX ? FONT_FALLBACK_MAX : len;
     for (int i = 0; i < len; i++) {
       lua_rawgeti(L, idx, i+1);
       fonts[i] = *(RenFont**) luaL_checkudata(L, -1, API_TYPE_FONT);
       lua_pop(L, 1);
     }
-  return true;
+  }
+#ifdef LITE_USE_SDL_RENDERER
+  update_font_scale(window_renderer, fonts);
+#endif
+  return is_table;
 }
 
 static int f_font_copy(lua_State *L) {

src/renderer.c

@@ -54,6 +54,9 @@ typedef struct RenFont {
   FT_StreamRec stream;
   GlyphSet* sets[SUBPIXEL_BITMAPS_CACHED][MAX_LOADABLE_GLYPHSETS];
   float size, space_advance, tab_advance;
+#ifdef LITE_USE_SDL_RENDERER
+  int scale;
+#endif
   unsigned short max_height, baseline, height;
   ERenFontAntialiasing antialiasing;
   ERenFontHinting hinting;
@@ -62,6 +65,18 @@ typedef struct RenFont {
   char path[];
 } RenFont;
 
+#ifdef LITE_USE_SDL_RENDERER
+void update_font_scale(RenWindow *window_renderer, RenFont **fonts) {
+  const int surface_scale = renwin_get_surface(window_renderer).scale;
+  for (int i = 0; i < FONT_FALLBACK_MAX && fonts[i]; ++i) {
+    if (fonts[i]->scale != surface_scale) {
+      ren_font_group_set_size(window_renderer, fonts, fonts[0]->size);
+      return;
+    }
+  }
+}
+#endif
+
 static const char* utf8_to_codepoint(const char *p, unsigned *dst) {
   const unsigned char *up = (unsigned char*)p;
   unsigned res, n;
@@ -336,6 +351,9 @@ void ren_font_group_set_size(RenWindow *window_renderer, RenFont **fonts, float
     FT_Face face = fonts[i]->face;
     FT_Set_Pixel_Sizes(face, 0, (int)(size*surface_scale));
     fonts[i]->size = size;
+#ifdef LITE_USE_SDL_RENDERER
+    fonts[i]->scale = surface_scale;
+#endif
     fonts[i]->height = (short)((face->height / (float)face->units_per_EM) * size);
     fonts[i]->baseline = (short)((face->ascender / (float)face->units_per_EM) * size);
     FT_Load_Char(face, ' ', font_set_load_options(fonts[i]));

src/renderer.h

@@ -33,6 +33,9 @@ int ren_font_group_get_tab_size(RenFont **font);
 int ren_font_group_get_height(RenFont **font);
 float ren_font_group_get_size(RenFont **font);
 void ren_font_group_set_size(RenWindow *window_renderer, RenFont **font, float size);
+#ifdef LITE_USE_SDL_RENDERER
+void update_font_scale(RenWindow *window_renderer, RenFont **fonts);
+#endif
 void ren_font_group_set_tab_size(RenFont **font, int n);
 double ren_font_group_get_width(RenWindow *window_renderer, RenFont **font, const char *text, size_t len, int *x_offset);
 double ren_draw_text(RenSurface *rs, RenFont **font, const char *text, size_t len, float x, int y, RenColor color);

src/renwindow.c

@@ -83,12 +83,15 @@ RenSurface renwin_get_surface(RenWindow *ren) {
 #endif
 }
 
-void renwin_resize_surface(UNUSED RenWindow *ren) {
+void renwin_resize_surface(RenWindow *ren) {
 #ifdef LITE_USE_SDL_RENDERER
-  int new_w, new_h;
+  int new_w, new_h, new_scale;
   SDL_GL_GetDrawableSize(ren->window, &new_w, &new_h);
+  new_scale = query_surface_scale(ren);
   /* Note that (w, h) may differ from (new_w, new_h) on retina displays. */
-  if (new_w != ren->rensurface.surface->w || new_h != ren->rensurface.surface->h) {
+  if (new_scale != ren->rensurface.scale ||
+      new_w != ren->rensurface.surface->w ||
+      new_h != ren->rensurface.surface->h) {
     renwin_init_surface(ren);
     renwin_clip_to_surface(ren);
     setup_renderer(ren, new_w, new_h);