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Add average advance width to the font metrics structure, using the X glyph as a best guess.
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3 changed files with 15 additions and 1 deletions
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@ -78,6 +78,7 @@ pub struct FontMetrics {
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pub ascent: Au,
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pub descent: Au,
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pub max_advance: Au,
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pub average_advance: Au,
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pub line_gap: Au,
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}
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@ -235,6 +235,11 @@ impl FontHandleMethods for FontHandle {
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}
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}
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let average_advance = self.glyph_index('x')
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.and_then(|idx| self.glyph_h_advance(idx))
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.map(|advance| self.font_units_to_au(advance))
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.unwrap_or(max_advance_width);
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let metrics = FontMetrics {
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underline_size: underline_size,
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underline_offset: underline_offset,
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@ -246,6 +251,7 @@ impl FontHandleMethods for FontHandle {
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ascent: ascent,
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descent: -descent, // linux font's seem to use the opposite sign from mac
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max_advance: max_advance,
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average_advance: average_advance,
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line_gap: height,
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};
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@ -153,6 +153,12 @@ impl FontHandleMethods for FontHandle {
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let scale = px_to_pt(self.ctfont.pt_size() as f64) / (ascent + descent);
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let line_gap = (ascent + descent + leading + 0.5).floor();
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let max_advance_width = Au::from_pt(bounding_rect.size.width as f64);
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let average_advance = self.glyph_index('x')
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.and_then(|idx| self.glyph_h_advance(idx))
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.map(|advance| Au::from_frac_px(advance))
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.unwrap_or(max_advance_width);
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let metrics = FontMetrics {
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underline_size: Au::from_pt(self.ctfont.underline_thickness() as f64),
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// TODO(Issue #201): underline metrics are not reliable. Have to pull out of font table
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@ -168,7 +174,8 @@ impl FontHandleMethods for FontHandle {
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em_size: em_size,
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ascent: Au::from_pt(ascent * scale),
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descent: Au::from_pt(descent * scale),
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max_advance: Au::from_pt(bounding_rect.size.width as f64),
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max_advance: max_advance_width,
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average_advance: average_advance,
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line_gap: Au::from_frac_px(line_gap),
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};
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debug!("Font metrics (@{:f} pt): {:?}", self.ctfont.pt_size() as f64, metrics);
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