Finish implementation of textium::Font::make_atlas()

textium/src/rasterizer.rs

@@ -28,7 +28,7 @@ impl<'a> Font<'a> {
     ///
     /// The packer may enlarge the bitmap beyond its initial dimensions in order to fit all glyphs.
     pub fn make_atlas<I>(&self, chrs: I, scale: f32, margin: u32, width: usize, height: usize)
-        -> (FontAtlas, Bitmap<u8>)
+        -> (FontAtlas, Bitmap<u8>, f32)
             where I: Iterator<Item=char>
     {
         let mut atlas = FontAtlas {glyph_data: HashMap::new()};
@@ -37,10 +37,25 @@ impl<'a> Font<'a> {
         for chr in chrs {
             if let Some((mut info, rendered)) = self.rasterize_char(chr, scale) {
                 let r = packer.pack_resize(&rendered);
+                info.bounding_box = r;
+                atlas.glyph_data.insert(chr, info);
+            } else if chr == ' ' {
+                // generate a blank pixel for the space texture
+                let (mut info, _) = self.rasterize_char(' ', scale).unwrap();
+                let empty_bitmap = Bitmap::new(1, 1);
+                let r = packer.pack_resize(&empty_bitmap, |(w, h)| (w*2, h*2));
+                info.bounding_box = r;
+                atlas.glyph_data.insert(chr, info);
+            } else {
+                // TODO: use a Result instead of panic!ing
+                panic!("Cannot render character {}", chr);
             }
         }
 
-        (atlas, packer.into_buf())
+        let v_metrics = self.font.v_metrics(rusttype::Scale::uniform(scale));
+        let line_height = v_metrics.ascent + v_metrics.descent + v_metrics.line_gap;
+
+        (atlas, packer.into_buf(), line_height)
     }
 
     pub fn rasterize_char(&self, chr: char, scale: f32)