Add tests for font metrics and their estimators

2025-09-17 19:05:13 -07:00 · 2025-09-17 19:05:13 -07:00 · 03a707b2c0
parent e1b2f6f021
commit 03a707b2c0
1 changed files with 122 additions and 0 deletions
--- a/src/font/Collection.zig
+++ b/src/font/Collection.zig
@ -1369,3 +1369,125 @@ test "adjusted sizes" {
        );
    }
 }
+
+test "face metrics" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+    const narrowFont = font.embedded.cozette;
+    const wideFont = font.embedded.geist_mono;
+
+    var lib = try Library.init(alloc);
+    defer lib.deinit();
+
+    var c = init();
+    defer c.deinit(alloc);
+    const size: DesiredSize = .{ .points = 12, .xdpi = 96, .ydpi = 96 };
+    c.load_options = .{ .library = lib, .size = size };
+
+    const narrowIndex = try c.add(alloc, try .init(
+        lib,
+        narrowFont,
+        .{ .size = size },
+    ), .{
+        .style = .regular,
+        .fallback = false,
+        .size_adjustment = .none,
+    });
+    const wideIndex = try c.add(alloc, try .init(
+        lib,
+        wideFont,
+        .{ .size = size },
+    ), .{
+        .style = .regular,
+        .fallback = false,
+        .size_adjustment = .none,
+    });
+
+    const narrowMetrics = (try c.getFace(narrowIndex)).getMetrics();
+    const wideMetrics = (try c.getFace(wideIndex)).getMetrics();
+
+    // Verify provided/measured metrics. Measured
+    // values are backend-dependent due to hinting.
+    if (options.backend != .web_canvas) {
+        try std.testing.expectEqual(font.Metrics.FaceMetrics{
+            .px_per_em = 16.0,
+            .cell_width = switch (options.backend) {
+                .freetype,
+                .fontconfig_freetype,
+                .coretext_freetype,
+                => 8.0,
+                .coretext,
+                .coretext_harfbuzz,
+                .coretext_noshape,
+                => 7.3828125,
+                .web_canvas => unreachable,
+            },
+            .ascent = 12.3046875,
+            .descent = -3.6953125,
+            .line_gap = 0.0,
+            .underline_position = -1.2265625,
+            .underline_thickness = 1.2265625,
+            .strikethrough_position = 6.15625,
+            .strikethrough_thickness = 1.234375,
+            .cap_height = 9.84375,
+            .ex_height = 7.3828125,
+            .ascii_height = switch (options.backend) {
+                .freetype,
+                .fontconfig_freetype,
+                .coretext_freetype,
+                => 18.0625,
+                .coretext,
+                .coretext_harfbuzz,
+                .coretext_noshape,
+                => 16.0,
+                .web_canvas => unreachable,
+            },
+        }, narrowMetrics);
+        try std.testing.expectEqual(font.Metrics.FaceMetrics{
+            .px_per_em = 16.0,
+            .cell_width = switch (options.backend) {
+                .freetype,
+                .fontconfig_freetype,
+                .coretext_freetype,
+                => 10.0,
+                .coretext,
+                .coretext_harfbuzz,
+                .coretext_noshape,
+                => 9.6,
+                .web_canvas => unreachable,
+            },
+            .ascent = 14.72,
+            .descent = -3.52,
+            .line_gap = 1.6,
+            .underline_position = -1.6,
+            .underline_thickness = 0.8,
+            .strikethrough_position = 4.24,
+            .strikethrough_thickness = 0.8,
+            .cap_height = 11.36,
+            .ex_height = 8.48,
+            .ascii_height = switch (options.backend) {
+                .freetype,
+                .fontconfig_freetype,
+                .coretext_freetype,
+                => 16.0,
+                .coretext,
+                .coretext_harfbuzz,
+                .coretext_noshape,
+                => 15.472000000000001,
+                .web_canvas => unreachable,
+            },
+        }, wideMetrics);
+    }
+
+    // Verify estimated metrics. icWidth() should equal the smaller of
+    // 2 * cell_width and ascii_height. For a narrow (wide) font, the
+    // smaller quantity is the former (latter).
+    try std.testing.expectEqual(
+        2 * narrowMetrics.cell_width,
+        narrowMetrics.icWidth(),
+    );
+    try std.testing.expectEqual(
+        wideMetrics.ascii_height,
+        wideMetrics.icWidth(),
+    );
+}