LibGfx: Let FontCascadeList quickly reject out-of-range code points

By keeping track of the enclosing range around all Unicode ranges of a FontCascadeList entry, we can quickly reject any code point that's outside all ranges. This knocks font_for_code_point() from 7% to 3% in the profile when scrolling on https://screenshotone.com/
Author: https://github.com/awesomekling Commit: 0fece0650e Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5442
2025-09-07 10:06:03 +00:00 · 2025-07-14 17:59:58 +02:00 · 2025-07-14 17:59:58 +02:00 · 0fece0650e · 2025-07-14 22:54:07 +00:00
commit 0fece0650e
parent 488333aa4b
2 changed files with 24 additions and 4 deletions
--- a/Libraries/LibGfx/FontCascadeList.h
+++ b/Libraries/LibGfx/FontCascadeList.h
@ -40,7 +40,13 @@ public:

    struct Entry {
        NonnullRefPtr<Font const> font;
-        Optional<Vector<UnicodeRange>> unicode_ranges;
+        struct RangeData {
+            // The enclosing range is the union of all Unicode ranges. Used for fast skipping.
+            UnicodeRange enclosing_range;
+
+            Vector<UnicodeRange> unicode_ranges;
+        };
+        Optional<RangeData> range_data;
    };

    void set_last_resort_font(NonnullRefPtr<Font> font) { m_last_resort_font = move(font); }