Fixed #35 in debug mode

src/font.rs

@@ -106,6 +106,8 @@ pub struct LineMetrics {
 impl LineMetrics {
  /// Creates a new line metrics struct and computes the new line size.
  pub fn new(ascent: i16, descent: i16, line_gap: i16) -> LineMetrics {
+ // Operations between this values can exceed i16, so we extend to i32 here.
+ let (ascent, descent, line_gap) = (ascent as i32, descent as i32, line_gap as i32);
  LineMetrics {
  ascent: ascent as f32,
  descent: descent as f32,
@@ -231,12 +233,15 @@ impl Font {
  Ok(f) => f,
  Err(_) => return Err("Malformed font."),
  };
+ // TrueType and OpenType define their point order opposite of eachother.
  let reverse_points =
  if face.has_table(TableName::GlyphVariations) || face.has_table(TableName::GlyphData) {
  false
  } else {
  true
  };
+ // This is fairly degenerate, but fonts without a units per em will be assumed to have the
+ // common default for compatibility.
  let units_per_em = face.units_per_em().unwrap_or(1000) as f32;
 
  // Collect all the unique codepoint to glyph mappings.