Upload spectral-font/src/metrics.rs

spectral-font/src/metrics.rs

@@ -0,0 +1,62 @@
+use fontdue::{Font, LineMetrics};
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct FontMetrics {
+    pub cell_width: f32,
+    pub cell_height: f32,
+    pub baseline: f32,
+    pub underline_position: f32,
+    pub underline_thickness: f32,
+    pub strikethrough_position: f32,
+    pub strikethrough_thickness: f32,
+    pub ascent: f32,
+    pub descent: f32,
+    pub line_gap: f32,
+}
+
+impl FontMetrics {
+    pub fn from_fontdue(
+        font: &Font,
+        px: f32,
+        adjust_height: Option<f32>,
+        adjust_width: Option<f32>,
+    ) -> Self {
+        let h = font.horizontal_line_metrics(px).unwrap_or(LineMetrics {
+            ascent: px * 0.8,
+            descent: px * 0.2,
+            line_gap: 0.0,
+            new_line_size: px,
+        });
+
+        let v = font.vertical_line_metrics(px).unwrap_or(LineMetrics {
+            ascent: px, descent: 0.0, line_gap: 0.0, new_line_size: px,
+        });
+
+        let mut cell_width = v.new_line_size;
+        let mut cell_height = h.new_line_size;
+
+        let mut max_advance = 0.0f32;
+        for ch in (32u8..=126).map(|b| b as char) {
+            let idx = font.lookup_glyph_index(ch);
+            let (m, _) = font.rasterize_indexed(idx, px);
+            max_advance = max_advance.max(m.advance_width);
+        }
+        if max_advance > 0.0 { cell_width = max_advance; }
+
+        if let Some(adj) = adjust_height { cell_height *= adj; }
+        if let Some(adj) = adjust_width { cell_width *= adj; }
+
+        Self {
+            cell_width,
+            cell_height,
+            baseline: h.ascent,
+            underline_position: h.ascent * 0.9,
+            underline_thickness: px * 0.05,
+            strikethrough_position: h.ascent * 0.55,
+            strikethrough_thickness: px * 0.05,
+            ascent: h.ascent,
+            descent: h.descent,
+            line_gap: h.line_gap,
+        }
+    }
+}