Merge pull request #1970 from qwerasd205/shaper-cache-reset

shaper/coretext: reset font cache on grid change

src/font/shaper/coretext.zig

@@ -59,6 +59,10 @@ pub const Shaper = struct {
     /// attributed strings.
     cached_fonts: std.ArrayListUnmanaged(?*macos.foundation.Dictionary),
 
+    /// The grid that our cached fonts correspond to.
+    /// If the grid changes then we need to reset our cache.
+    cached_font_grid: usize,
+
     /// The list of CoreFoundation objects to release on the dedicated
     /// release thread. This is built up over the course of shaping and
     /// sent to the release thread when endFrame is called.
@@ -241,6 +245,7 @@ pub const Shaper = struct {
             .features = feats,
             .writing_direction = writing_direction,
             .cached_fonts = .{},
+            .cached_font_grid = 0,
             .cf_release_pool = .{},
             .cf_release_thread = cf_release_thread,
             .cf_release_thr = cf_release_thr,
@@ -487,6 +492,30 @@ pub const Shaper = struct {
         grid: *font.SharedGrid,
         index: font.Collection.Index,
     ) !*macos.foundation.Dictionary {
+        // If this grid doesn't match the one we've cached fonts for,
+        // then we reset the cache list since it's no longer valid.
+        // We use an intFromPtr rather than direct pointer comparison
+        // because we don't want anyone to inadvertenly use the pointer.
+        const grid_id: usize = @intFromPtr(grid);
+        if (grid_id != self.cached_font_grid) {
+            if (self.cached_font_grid > 0) {
+                // Put all the currently cached fonts in to
+                // the release pool before clearing the list.
+                try self.cf_release_pool.ensureUnusedCapacity(
+                    self.alloc,
+                    self.cached_fonts.items.len,
+                );
+                for (self.cached_fonts.items) |ft| {
+                    if (ft) |f| {
+                        self.cf_release_pool.appendAssumeCapacity(f);
+                    }
+                }
+                self.cached_fonts.clearRetainingCapacity();
+            }
+
+            self.cached_font_grid = grid_id;
+        }
+
         const index_int = index.int();
 
         // The cached fonts are indexed directly by the font index, since