Fix font height cache when changing GUI scaling.

src/fontcache.cpp

@@ -189,6 +189,13 @@ bool SpriteFontCache::GetDrawGlyphShadow()
 /* static */ FontCache *FontCache::caches[FS_END] = { new SpriteFontCache(FS_NORMAL), new SpriteFontCache(FS_SMALL), new SpriteFontCache(FS_LARGE), new SpriteFontCache(FS_MONO) };
 int font_height_cache[FS_END];
 
+void UpdateFontHeightCache()
+{
+	for (int i = 0; i < FS_END; i++) {
+		font_height_cache[i] = FontCache::Get((FontSize) i)->GetHeight();
+	}
+}
+
 #ifdef WITH_FREETYPE
 #include <ft2build.h>
 #include FT_FREETYPE_H

src/fontcache.h

@@ -21,6 +21,8 @@ static const GlyphID SPRITE_GLYPH = 1U << 30;
 
 extern int font_height_cache[FS_END]; ///< Cache of font heights
 
+void UpdateFontHeightCache();
+
 /** Font cache for basic fonts. */
 class FontCache {
 private:

src/settings.cpp

@@ -1080,12 +1080,14 @@ static bool InvalidateVehTimetableWindow(int32 p1)
 static bool ZoomMinMaxChanged(int32 p1)
 {
 	extern void ConstrainAllViewportsZoom();
+	extern void UpdateFontHeightCache();
 	ConstrainAllViewportsZoom();
 	GfxClearSpriteCache();
 	if (_settings_client.gui.zoom_min > _gui_zoom) {
 		/* Restrict GUI zoom if it is no longer available. */
 		_gui_zoom = _settings_client.gui.zoom_min;
 		UpdateCursorSize();
+		UpdateFontHeightCache();
 		LoadStringWidthTable();
 	}
 	return true;

src/settings_gui.cpp

@@ -528,9 +528,11 @@ struct GameOptionsWindow : Window {
 				break;
 
 			case WID_GO_GUI_ZOOM_DROPDOWN:
+				extern void UpdateFontHeightCache();
 				GfxClearSpriteCache();
 				_gui_zoom = (ZoomLevel)(ZOOM_LVL_OUT_4X - index);
 				UpdateCursorSize();
+				UpdateFontHeightCache();
 				LoadStringWidthTable();
 				break;