Vendor things

third-party/vendor/ttf-parser-0.15.2/src/tables/loca.rs

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+//! An [Index to Location Table](https://docs.microsoft.com/en-us/typography/opentype/spec/loca)
+//! implementation.
+
+use core::num::NonZeroU16;
+use core::ops::Range;
+
+use crate::{GlyphId, IndexToLocationFormat};
+use crate::parser::{Stream, LazyArray16, NumFrom};
+
+/// An [Index to Location Table](https://docs.microsoft.com/en-us/typography/opentype/spec/loca).
+#[derive(Clone, Copy, Debug)]
+pub enum Table<'a> {
+    /// Short offsets.
+    Short(LazyArray16<'a, u16>),
+    /// Long offsets.
+    Long(LazyArray16<'a, u32>),
+}
+
+impl<'a> Table<'a> {
+    /// Parses a table from raw data.
+    ///
+    /// - `number_of_glyphs` is from the `maxp` table.
+    /// - `format` is from the `head` table.
+    pub fn parse(
+        number_of_glyphs: NonZeroU16,
+        format: IndexToLocationFormat,
+        data: &'a [u8],
+    ) -> Option<Self> {
+        // The number of ranges is `maxp.numGlyphs + 1`.
+        //
+        // Check for overflow first.
+        let total = if number_of_glyphs.get() == core::u16::MAX {
+            number_of_glyphs.get()
+        } else {
+            number_of_glyphs.get() + 1
+        };
+
+        let mut s = Stream::new(data);
+        match format {
+            IndexToLocationFormat::Short => {
+                Some(Table::Short(s.read_array16::<u16>(total)?))
+            }
+            IndexToLocationFormat::Long => {
+                Some(Table::Long(s.read_array16::<u32>(total)?))
+            }
+        }
+    }
+
+    /// Returns offsets length.
+    #[inline]
+    pub fn len(&self) -> u16 {
+        match self {
+            Table::Short(ref array) => array.len(),
+            Table::Long(ref array) => array.len(),
+        }
+    }
+
+    /// Returns glyph's range in the `glyf` table.
+    #[inline]
+    pub fn glyph_range(&self, glyph_id: GlyphId) -> Option<Range<usize>> {
+        let glyph_id = glyph_id.0;
+        if glyph_id == core::u16::MAX {
+            return None;
+        }
+
+        // Glyph ID must be smaller than total number of values in a `loca` array.
+        if glyph_id + 1 >= self.len() {
+            return None;
+        }
+
+        let range = match self {
+            Table::Short(ref array) => {
+                // 'The actual local offset divided by 2 is stored.'
+                usize::from(array.get(glyph_id)?) * 2 .. usize::from(array.get(glyph_id + 1)?) * 2
+            }
+            Table::Long(ref array) => {
+                usize::num_from(array.get(glyph_id)?) .. usize::num_from(array.get(glyph_id + 1)?)
+            }
+        };
+
+        if range.start >= range.end {
+            // 'The offsets must be in ascending order.'
+            // And range cannot be empty.
+            None
+        } else {
+            Some(range)
+        }
+    }
+}