Split into objdiff-core / objdiff-gui; update egui to 0.26.2

objdiff-gui/src/fonts/matching.rs

@@ -0,0 +1,146 @@
+// font-kit/src/matching.rs
+//
+// Copyright © 2018 The Pathfinder Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Determines the closest font matching a description per the CSS Fonts Level 3 specification.
+
+use float_ord::FloatOrd;
+use font_kit::{
+    error::SelectionError,
+    properties::{Properties, Stretch, Style, Weight},
+};
+
+/// This follows CSS Fonts Level 3 § 5.2 [1].
+///
+/// https://drafts.csswg.org/css-fonts-3/#font-style-matching
+pub fn find_best_match(
+    candidates: &[Properties],
+    query: &Properties,
+) -> Result<usize, SelectionError> {
+    // Step 4.
+    let mut matching_set: Vec<usize> = (0..candidates.len()).collect();
+    if matching_set.is_empty() {
+        return Err(SelectionError::NotFound);
+    }
+
+    // Step 4a (`font-stretch`).
+    let matching_stretch = if matching_set
+        .iter()
+        .any(|&index| candidates[index].stretch == query.stretch)
+    {
+        // Exact match.
+        query.stretch
+    } else if query.stretch <= Stretch::NORMAL {
+        // Closest width, first checking narrower values and then wider values.
+        match matching_set
+            .iter()
+            .filter(|&&index| candidates[index].stretch < query.stretch)
+            .min_by_key(|&&index| FloatOrd(query.stretch.0 - candidates[index].stretch.0))
+        {
+            Some(&matching_index) => candidates[matching_index].stretch,
+            None => {
+                let matching_index = *matching_set
+                    .iter()
+                    .min_by_key(|&&index| FloatOrd(candidates[index].stretch.0 - query.stretch.0))
+                    .unwrap();
+                candidates[matching_index].stretch
+            }
+        }
+    } else {
+        // Closest width, first checking wider values and then narrower values.
+        match matching_set
+            .iter()
+            .filter(|&&index| candidates[index].stretch > query.stretch)
+            .min_by_key(|&&index| FloatOrd(candidates[index].stretch.0 - query.stretch.0))
+        {
+            Some(&matching_index) => candidates[matching_index].stretch,
+            None => {
+                let matching_index = *matching_set
+                    .iter()
+                    .min_by_key(|&&index| FloatOrd(query.stretch.0 - candidates[index].stretch.0))
+                    .unwrap();
+                candidates[matching_index].stretch
+            }
+        }
+    };
+    matching_set.retain(|&index| candidates[index].stretch == matching_stretch);
+
+    // Step 4b (`font-style`).
+    let style_preference = match query.style {
+        Style::Italic => [Style::Italic, Style::Oblique, Style::Normal],
+        Style::Oblique => [Style::Oblique, Style::Italic, Style::Normal],
+        Style::Normal => [Style::Normal, Style::Oblique, Style::Italic],
+    };
+    let matching_style = *style_preference
+        .iter()
+        .find(|&query_style| {
+            matching_set.iter().any(|&index| candidates[index].style == *query_style)
+        })
+        .unwrap();
+    matching_set.retain(|&index| candidates[index].style == matching_style);
+
+    // Step 4c (`font-weight`).
+    //
+    // The spec doesn't say what to do if the weight is between 400 and 500 exclusive, so we
+    // just use 450 as the cutoff.
+    let matching_weight =
+        if matching_set.iter().any(|&index| candidates[index].weight == query.weight) {
+            query.weight
+        } else if query.weight >= Weight(400.0)
+            && query.weight < Weight(450.0)
+            && matching_set.iter().any(|&index| candidates[index].weight == Weight(500.0))
+        {
+            // Check 500 first.
+            Weight(500.0)
+        } else if query.weight >= Weight(450.0)
+            && query.weight <= Weight(500.0)
+            && matching_set.iter().any(|&index| candidates[index].weight == Weight(400.0))
+        {
+            // Check 400 first.
+            Weight(400.0)
+        } else if query.weight <= Weight(500.0) {
+            // Closest weight, first checking thinner values and then fatter ones.
+            match matching_set
+                .iter()
+                .filter(|&&index| candidates[index].weight <= query.weight)
+                .min_by_key(|&&index| FloatOrd(query.weight.0 - candidates[index].weight.0))
+            {
+                Some(&matching_index) => candidates[matching_index].weight,
+                None => {
+                    let matching_index = *matching_set
+                        .iter()
+                        .min_by_key(|&&index| FloatOrd(candidates[index].weight.0 - query.weight.0))
+                        .unwrap();
+                    candidates[matching_index].weight
+                }
+            }
+        } else {
+            // Closest weight, first checking fatter values and then thinner ones.
+            match matching_set
+                .iter()
+                .filter(|&&index| candidates[index].weight >= query.weight)
+                .min_by_key(|&&index| FloatOrd(candidates[index].weight.0 - query.weight.0))
+            {
+                Some(&matching_index) => candidates[matching_index].weight,
+                None => {
+                    let matching_index = *matching_set
+                        .iter()
+                        .min_by_key(|&&index| FloatOrd(query.weight.0 - candidates[index].weight.0))
+                        .unwrap();
+                    candidates[matching_index].weight
+                }
+            }
+        };
+    matching_set.retain(|&index| candidates[index].weight == matching_weight);
+
+    // Step 4d concerns `font-size`, but fonts in `font-kit` are unsized, so we ignore that.
+
+    // Return the result.
+    matching_set.into_iter().next().ok_or(SelectionError::NotFound)
+}