Player only loading smallest size of bitmap font

[maxymax13]

Game: OFF (v1.6.1)

Steps to reproduce:

1. Move OFF\Profont.fon to OFF\Font\Font.fon
2. Intended font loads but everything is small

RPG_RT:

EasyRPG:

Manually changing the font through the F1 menu instead, all sizes show the smallest size and only change the line height

Tested on latest continuous build (Windows x86 and x86_64)

[Ghabry]

According to FontForge the bitmap font has indeed multiple sizes. I checked in our code and while looking for the best size the list only contained one.

This must be first time where AI really helped me: I was clueless where the other sizes are hidden. Turns out that it is necessary to load all faces and for all faces loop over the sizes (our code always only loaded the first face).

When implementing this my assumption was that Bitmap fonts have one Face with various sizes but it's actually multiple faces (one face per size).

Love low level APIs cough.

Though the calculation of the baseline is now incorrect (large fonts are rendered lower than expected). Still investigation this one (and must be compared to Maniacs).

diff --git a/src/font.cpp b/src/font.cpp
index 31748586d..1b884b5ce 100644
--- a/src/font.cpp
+++ b/src/font.cpp
@@ -17,6 +17,7 @@
 
 // Headers
 #include <cstdint>
+#include <limits>
 #include <map>
 #include <type_traits>
 #include <vector>
@@ -287,6 +288,58 @@ FTFont::FTFont(Filesystem_Stream::InputStream is, int size, bool bold, bool ital
 		return;
 	}
 
+	if (face->num_faces > 1) {
+		// When there are multiple faces and the font is not scalable try to load the face where the size is closest
+		// (required for BitmapFonts)
+		if (!FT_HAS_COLOR(face) && !FT_IS_SCALABLE(face)) {
+			auto num_faces = face->num_faces;
+			FT_Done_Face(face);
+			face = nullptr;
+
+			// Find a predefined height that is as close as possible to the requested height
+			int closest = std::numeric_limits<int>::max();
+
+			// Stores the best match
+			FT_Face best_face = nullptr;
+
+			for (FT_Long i = 0; i < num_faces; ++i) {
+				if (FT_New_Memory_Face(library, ft_buffer.data(), ft_buffer.size(), i, &face) != 0) {
+					continue;
+				}
+
+				for (int j = 0; j < face->num_fixed_sizes; ++j) {
+					int face_height = face->available_sizes[j].height;
+					int diff = abs(face_height - size);
+					Output::Debug("i={}, j={}, requested={}, size_height={}, closest={}", i, j, size, face_height, closest);
+
+					if (diff < closest) {
+						Output::Debug("NEW CLOSEST");
+						closest = diff;
+
+						// Throw away previous best_face
+						if (best_face && face != best_face) {
+							FT_Done_Face(best_face);
+						}
+
+						best_face = face;
+					}
+				}
+
+				// If this face is not the new best throw it away
+				if (face != best_face) {
+					FT_Done_Face(face);
+					face = nullptr;
+				}
+			}
+
+			face = best_face;
+
+			if (face == nullptr) {
+				return;
+			}
+		}
+	}
+
 	if (face->num_charmaps > 0) {
 		// Force unicode charmap
 		if (FT_Select_Charmap(face, FT_ENCODING_UNICODE) != 0) {
@@ -564,7 +617,9 @@ void FTFont::SetSize(int height, bool create) {
 
 		FT_Set_Pixel_Sizes(face, 0, height);
 	} else {
-		FT_Set_Pixel_Sizes(face, 0, face->available_sizes->height);
+		// Use the closest available
+		height = face->available_sizes->height;
+		FT_Set_Pixel_Sizes(face, 0, height);
 	}
 
 #ifdef HAVE_HARFBUZZ