Handle the height of letters correctly

agb-image-converter/src/font_loader.rs

@@ -22,11 +22,17 @@ pub fn load_font(font_data: &[u8], pixels_per_em: f32) -> TokenStream {
     )
     .expect("Invalid font data");
 
+    let line_metrics = font.horizontal_line_metrics(pixels_per_em).unwrap();
+
+    let line_height = line_metrics.new_line_size as i32;
+    let ascent = line_metrics.ascent as i32;
+
     let font = (0..128)
         .map(|i| font.rasterize(char::from_u32(i).unwrap(), pixels_per_em))
         .map(|(metrics, bitmap)| {
             let width = metrics.width;
             let height = metrics.height;
+
             LetterData {
                 width,
                 height,
@@ -57,6 +63,6 @@ pub fn load_font(font_data: &[u8], pixels_per_em: f32) -> TokenStream {
         });
 
     quote![
-        agb::display::Font::new(&[#(#font),*])
+        agb::display::Font::new(&[#(#font),*], #line_height, #ascent)
     ]
 }

agb/src/display/font.rs

@@ -33,11 +33,17 @@ impl FontLetter {
 
 pub struct Font {
     letters: &'static [FontLetter],
+    line_height: i32,
+    ascent: i32,
 }
 
 impl Font {
-    pub const fn new(letters: &'static [FontLetter]) -> Self {
+    pub const fn new(letters: &'static [FontLetter], line_height: i32, ascent: i32) -> Self {
-        Self { letters }
+        Self {
+            letters,
+            line_height,
+            ascent,
+        }
     }
 
     fn letter(&self, letter: char) -> &'static FontLetter {
@@ -89,11 +95,12 @@ impl Font {
             let letter = self.letter(c);
 
             let xmin = (current_x_pos + letter.xmin as i32).max(0);
+            let y_start = current_y_pos + self.ascent - letter.height as i32 - letter.ymin as i32;
 
             for letter_y in 0..(letter.height as i32) {
                 for letter_x in 0..(letter.width as i32) {
                     let x = letter_x + xmin;
-                    let y = current_y_pos + letter_y;
+                    let y = y_start + letter_y;
 
                     let px = letter.data[(letter_x + letter_y * letter.width as i32) as usize];