From 0d8bc2b4330e04932a938f69e881be9158151d25 Mon Sep 17 00:00:00 2001
From: Daniel Patterson <me@danielpatterson.dev>
Date: Sun, 26 Jan 2025 00:30:18 +0000
Subject: [PATCH] Introduce `font-shaping-break` config option

---
 src/config.zig                 |   1 +
 src/config/Config.zig          |  11 ++
 src/font/shaper/coretext.zig   | 219 +++++++++++++++++++++++++++------
 src/font/shaper/harfbuzz.zig   | 214 ++++++++++++++++++++++++++------
 src/font/shaper/noop.zig       |   3 +
 src/font/shaper/run.zig        |  63 +++++-----
 src/font/shaper/web_canvas.zig |   3 +
 src/renderer/Metal.zig         |   3 +
 src/renderer/OpenGL.zig        |   3 +
 9 files changed, 411 insertions(+), 109 deletions(-)

diff --git a/src/config.zig b/src/config.zig
index 75dbaae02b..640cf1d052 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -18,6 +18,7 @@ pub const ConfirmCloseSurface = Config.ConfirmCloseSurface;
 pub const CopyOnSelect = Config.CopyOnSelect;
 pub const CustomShaderAnimation = Config.CustomShaderAnimation;
 pub const FontSyntheticStyle = Config.FontSyntheticStyle;
+pub const FontShapingBreak = Config.FontShapingBreak;
 pub const FontStyle = Config.FontStyle;
 pub const FreetypeLoadFlags = Config.FreetypeLoadFlags;
 pub const Keybinds = Config.Keybinds;
diff --git a/src/config/Config.zig b/src/config/Config.zig
index 8396561692..2c45ea5364 100644
--- a/src/config/Config.zig
+++ b/src/config/Config.zig
@@ -257,6 +257,12 @@ pub const renamed = std.StaticStringMap([]const u8).initComptime(&.{
 /// This is currently only supported on macOS.
 @"font-thicken-strength": u8 = 255,
 
+/// Where to break font shaping runs.
+///
+/// Currently only one option, "cursor", which is enabled by default and breaks
+/// text runs under the cursor.
+@"font-shaping-break": FontShapingBreak = .{},
+
 /// What color space to use when performing alpha blending.
 ///
 /// This affects how text looks for different background/foreground color pairs.
@@ -5588,6 +5594,11 @@ pub const FontSyntheticStyle = packed struct {
     @"bold-italic": bool = true,
 };
 
+/// See "font-shaping-break" for documentation
+pub const FontShapingBreak = packed struct {
+    cursor: bool = true,
+};
+
 /// See "link" for documentation.
 pub const RepeatableLink = struct {
     const Self = @This();
diff --git a/src/font/shaper/coretext.zig b/src/font/shaper/coretext.zig
index e084a68c95..49ccbbe227 100644
--- a/src/font/shaper/coretext.zig
+++ b/src/font/shaper/coretext.zig
@@ -7,6 +7,7 @@ const trace = @import("tracy").trace;
 const font = @import("../main.zig");
 const os = @import("../../os/main.zig");
 const terminal = @import("../../terminal/main.zig");
+const config = @import("../../config.zig");
 const Feature = font.shape.Feature;
 const FeatureList = font.shape.FeatureList;
 const default_features = font.shape.default_features;
@@ -293,6 +294,7 @@ pub const Shaper = struct {
         row: terminal.Pin,
         selection: ?terminal.Selection,
         cursor_x: ?usize,
+        break_config: config.FontShapingBreak,
     ) font.shape.RunIterator {
         return .{
             .hooks = .{ .shaper = self },
@@ -301,6 +303,7 @@ pub const Shaper = struct {
             .row = row,
             .selection = selection,
             .cursor_x = cursor_x,
+            .break_config = break_config,
         };
     }
 
@@ -600,6 +603,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| count += 1;
@@ -619,6 +623,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| count += 1;
@@ -639,6 +644,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| count += 1;
@@ -660,6 +666,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| count += 1;
@@ -707,6 +714,7 @@ test "run iterator: empty cells with background set" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         {
             const run = (try it.next(alloc)).?;
@@ -743,6 +751,7 @@ test "shape" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -778,6 +787,7 @@ test "shape nerd fonts" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -806,6 +816,7 @@ test "shape inconsolata ligs" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -831,6 +842,7 @@ test "shape inconsolata ligs" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -864,6 +876,7 @@ test "shape monaspace ligs" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -898,6 +911,7 @@ test "shape left-replaced lig in last run" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -932,6 +946,7 @@ test "shape left-replaced lig in early run" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
 
         const run = (try it.next(alloc)).?;
@@ -963,6 +978,7 @@ test "shape U+3C9 with JB Mono" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
 
         var run_count: usize = 0;
@@ -996,6 +1012,7 @@ test "shape emoji width" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1036,6 +1053,7 @@ test "shape emoji width long" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1072,6 +1090,7 @@ test "shape variation selector VS15" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1107,6 +1126,7 @@ test "shape variation selector VS16" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1139,6 +1159,7 @@ test "shape with empty cells in between" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1177,6 +1198,7 @@ test "shape Chinese characters" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1217,6 +1239,7 @@ test "shape box glyphs" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1257,6 +1280,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1280,6 +1304,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1303,6 +1328,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1326,6 +1352,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1349,6 +1376,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1381,6 +1409,7 @@ test "shape cursor boundary" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1390,26 +1419,142 @@ test "shape cursor boundary" {
         try testing.expectEqual(@as(usize, 1), count);
     }
 
-    // Cursor at index 0 is two runs
     {
-        // Get our run iterator
-        var shaper = &testdata.shaper;
-        var it = shaper.runIterator(
-            testdata.grid,
-            &screen,
-            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
-            null,
-            0,
-        );
-        var count: usize = 0;
-        while (try it.next(alloc)) |run| {
-            count += 1;
-            _ = try shaper.shape(run);
+        // Cursor at index 0 is two runs
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                0,
+                .{ .cursor = true },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 2), count);
+        }
+        // And without cursor splitting remains one
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                0,
+                .{ .cursor = false },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 1), count);
         }
-        try testing.expectEqual(@as(usize, 2), count);
     }
 
-    // Cursor at index 1 is three runs
+    {
+        // Cursor at index 1 is three runs
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                1,
+                .{ .cursor = true },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 3), count);
+        }
+        // And without cursor splitting remains one
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                1,
+                .{ .cursor = false },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 1), count);
+        }
+    }
+    {
+        // Cursor at last col is two runs
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                9,
+                .{ .cursor = true },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 2), count);
+        }
+        // And without cursor splitting remains one
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                9,
+                .{ .cursor = false },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 1), count);
+        }
+    }
+}
+
+test "shape cursor boundary and colored emoji" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var testdata = try testShaper(alloc);
+    defer testdata.deinit();
+
+    // Make a screen with some data
+    var screen = try terminal.Screen.init(alloc, 3, 10, 0);
+    defer screen.deinit();
+    try screen.testWriteString("👍🏼");
+
+    // No cursor is full line
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -1418,17 +1563,18 @@ test "shape cursor boundary" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            1,
+            null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
             count += 1;
             _ = try shaper.shape(run);
         }
-        try testing.expectEqual(@as(usize, 3), count);
+        try testing.expectEqual(@as(usize, 1), count);
     }
 
-    // Cursor at last col is two runs
+    // Cursor on emoji does not split it
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -1437,30 +1583,16 @@ test "shape cursor boundary" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            9,
+            0,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
             count += 1;
             _ = try shaper.shape(run);
         }
-        try testing.expectEqual(@as(usize, 2), count);
+        try testing.expectEqual(@as(usize, 1), count);
     }
-}
-
-test "shape cursor boundary and colored emoji" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    var testdata = try testShaper(alloc);
-    defer testdata.deinit();
-
-    // Make a screen with some data
-    var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-    defer screen.deinit();
-    try screen.testWriteString("👍🏼");
-
-    // No cursor is full line
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -1469,7 +1601,8 @@ test "shape cursor boundary and colored emoji" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            null,
+            0,
+            .{ .cursor = false },
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1478,8 +1611,6 @@ test "shape cursor boundary and colored emoji" {
         }
         try testing.expectEqual(@as(usize, 1), count);
     }
-
-    // Cursor on emoji does not split it
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -1488,7 +1619,8 @@ test "shape cursor boundary and colored emoji" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            0,
+            1,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1506,6 +1638,7 @@ test "shape cursor boundary and colored emoji" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             1,
+            .{ .cursor = false },
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1536,6 +1669,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1560,6 +1694,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1585,6 +1720,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1610,6 +1746,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1634,6 +1771,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1674,6 +1812,7 @@ test "shape high plane sprite font codepoint" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     // We should get one run
     const run = (try it.next(alloc)).?;
diff --git a/src/font/shaper/harfbuzz.zig b/src/font/shaper/harfbuzz.zig
index 97292b9b0d..f379eb6d11 100644
--- a/src/font/shaper/harfbuzz.zig
+++ b/src/font/shaper/harfbuzz.zig
@@ -4,6 +4,7 @@ const Allocator = std.mem.Allocator;
 const harfbuzz = @import("harfbuzz");
 const font = @import("../main.zig");
 const terminal = @import("../../terminal/main.zig");
+const config = @import("../../config.zig");
 const Feature = font.shape.Feature;
 const FeatureList = font.shape.FeatureList;
 const default_features = font.shape.default_features;
@@ -94,6 +95,7 @@ pub const Shaper = struct {
         row: terminal.Pin,
         selection: ?terminal.Selection,
         cursor_x: ?usize,
+        break_config: config.FontShapingBreak,
     ) font.shape.RunIterator {
         return .{
             .hooks = .{ .shaper = self },
@@ -102,6 +104,7 @@ pub const Shaper = struct {
             .row = row,
             .selection = selection,
             .cursor_x = cursor_x,
+            .break_config = break_config,
         };
     }
 
@@ -231,6 +234,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| count += 1;
@@ -250,6 +254,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| count += 1;
@@ -270,6 +275,7 @@ test "run iterator" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |_| {
@@ -322,6 +328,7 @@ test "run iterator: empty cells with background set" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         {
             const run = (try it.next(alloc)).?;
@@ -359,6 +366,7 @@ test "shape" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -388,6 +396,7 @@ test "shape inconsolata ligs" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -413,6 +422,7 @@ test "shape inconsolata ligs" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -446,6 +456,7 @@ test "shape monaspace ligs" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -482,6 +493,7 @@ test "shape arabic forced LTR" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -519,6 +531,7 @@ test "shape emoji width" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -561,6 +574,7 @@ test "shape emoji width long" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -599,6 +613,7 @@ test "shape variation selector VS15" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -636,6 +651,7 @@ test "shape variation selector VS16" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -670,6 +686,7 @@ test "shape with empty cells in between" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -708,6 +725,7 @@ test "shape Chinese characters" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -748,6 +766,7 @@ test "shape box glyphs" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -789,6 +808,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -812,6 +832,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -835,6 +856,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -858,6 +880,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -881,6 +904,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -913,6 +937,7 @@ test "shape cursor boundary" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -922,26 +947,142 @@ test "shape cursor boundary" {
         try testing.expectEqual(@as(usize, 1), count);
     }
 
-    // Cursor at index 0 is two runs
     {
-        // Get our run iterator
-        var shaper = &testdata.shaper;
-        var it = shaper.runIterator(
-            testdata.grid,
-            &screen,
-            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
-            null,
-            0,
-        );
-        var count: usize = 0;
-        while (try it.next(alloc)) |run| {
-            count += 1;
-            _ = try shaper.shape(run);
+        // Cursor at index 0 is two runs
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                0,
+                .{ .cursor = true },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 2), count);
+        }
+        // And without cursor splitting remains one
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                0,
+                .{ .cursor = false },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 1), count);
         }
-        try testing.expectEqual(@as(usize, 2), count);
     }
 
-    // Cursor at index 1 is three runs
+    {
+        // Cursor at index 1 is three runs
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                1,
+                .{ .cursor = true },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 3), count);
+        }
+        // And without cursor splitting remains one
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                1,
+                .{ .cursor = false },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 1), count);
+        }
+    }
+    {
+        // Cursor at last col is two runs
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                9,
+                .{ .cursor = true },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 2), count);
+        }
+        // And without cursor splitting remains one
+        {
+            // Get our run iterator
+            var shaper = &testdata.shaper;
+            var it = shaper.runIterator(
+                testdata.grid,
+                &screen,
+                screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+                null,
+                9,
+                .{ .cursor = false },
+            );
+            var count: usize = 0;
+            while (try it.next(alloc)) |run| {
+                count += 1;
+                _ = try shaper.shape(run);
+            }
+            try testing.expectEqual(@as(usize, 1), count);
+        }
+    }
+}
+
+test "shape cursor boundary and colored emoji" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var testdata = try testShaper(alloc);
+    defer testdata.deinit();
+
+    // Make a screen with some data
+    var screen = try terminal.Screen.init(alloc, 3, 10, 0);
+    defer screen.deinit();
+    try screen.testWriteString("👍🏼");
+
+    // No cursor is full line
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -950,17 +1091,18 @@ test "shape cursor boundary" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            1,
+            null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
             count += 1;
             _ = try shaper.shape(run);
         }
-        try testing.expectEqual(@as(usize, 3), count);
+        try testing.expectEqual(@as(usize, 1), count);
     }
 
-    // Cursor at last col is two runs
+    // Cursor on emoji does not split it
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -969,30 +1111,16 @@ test "shape cursor boundary" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            9,
+            0,
+            .{ .cursor = true },
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
             count += 1;
             _ = try shaper.shape(run);
         }
-        try testing.expectEqual(@as(usize, 2), count);
+        try testing.expectEqual(@as(usize, 1), count);
     }
-}
-
-test "shape cursor boundary and colored emoji" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    var testdata = try testShaper(alloc);
-    defer testdata.deinit();
-
-    // Make a screen with some data
-    var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-    defer screen.deinit();
-    try screen.testWriteString("👍🏼");
-
-    // No cursor is full line
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -1001,7 +1129,8 @@ test "shape cursor boundary and colored emoji" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            null,
+            0,
+            .{ .cursor = false },
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1010,8 +1139,6 @@ test "shape cursor boundary and colored emoji" {
         }
         try testing.expectEqual(@as(usize, 1), count);
     }
-
-    // Cursor on emoji does not split it
     {
         // Get our run iterator
         var shaper = &testdata.shaper;
@@ -1020,7 +1147,8 @@ test "shape cursor boundary and colored emoji" {
             &screen,
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
-            0,
+            1,
+            .{ .cursor = true },
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1038,6 +1166,7 @@ test "shape cursor boundary and colored emoji" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             1,
+            .{ .cursor = false },
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1068,6 +1197,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1092,6 +1222,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1117,6 +1248,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1142,6 +1274,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1166,6 +1299,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
diff --git a/src/font/shaper/noop.zig b/src/font/shaper/noop.zig
index f8988f4ee9..1041954e6f 100644
--- a/src/font/shaper/noop.zig
+++ b/src/font/shaper/noop.zig
@@ -3,6 +3,7 @@ const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const trace = @import("tracy").trace;
 const font = @import("../main.zig");
+const config = @import("../../config.zig");
 const Face = font.Face;
 const Collection = font.Collection;
 const DeferredFace = font.DeferredFace;
@@ -75,6 +76,7 @@ pub const Shaper = struct {
         row: terminal.Pin,
         selection: ?terminal.Selection,
         cursor_x: ?usize,
+        break_config: config.FontShapingBreak,
     ) font.shape.RunIterator {
         return .{
             .hooks = .{ .shaper = self },
@@ -83,6 +85,7 @@ pub const Shaper = struct {
             .row = row,
             .selection = selection,
             .cursor_x = cursor_x,
+            .break_config = break_config,
         };
     }
 
diff --git a/src/font/shaper/run.zig b/src/font/shaper/run.zig
index 22d19979eb..69a36b88fc 100644
--- a/src/font/shaper/run.zig
+++ b/src/font/shaper/run.zig
@@ -6,6 +6,8 @@ const shape = @import("../shape.zig");
 const terminal = @import("../../terminal/main.zig");
 const autoHash = std.hash.autoHash;
 const Hasher = std.hash.Wyhash;
+const configpkg = @import("../../config.zig");
+const Config = configpkg.Config;
 
 /// A single text run. A text run is only valid for one Shaper instance and
 /// until the next run is created. A text run never goes across multiple
@@ -40,6 +42,7 @@ pub const RunIterator = struct {
     row: terminal.Pin,
     selection: ?terminal.Selection = null,
     cursor_x: ?usize = null,
+    break_config: configpkg.FontShapingBreak,
     i: usize = 0,
 
     pub fn next(self: *RunIterator, alloc: Allocator) !?TextRun {
@@ -175,36 +178,38 @@ pub const RunIterator = struct {
                 break :emoji null;
             };
 
-            // If our cursor is on this line then we break the run around the
-            // cursor. This means that any row with a cursor has at least
-            // three breaks: before, exactly the cursor, and after.
-            //
-            // We do not break a cell that is exactly the grapheme. If there
-            // are cells following that contain joiners, we allow those to
-            // break. This creates an effect where hovering over an emoji
-            // such as a skin-tone emoji is fine, but hovering over the
-            // joiners will show the joiners allowing you to modify the
-            // emoji.
-            if (!cell.hasGrapheme()) {
-                if (self.cursor_x) |cursor_x| {
-                    // Exactly: self.i is the cursor and we iterated once. This
-                    // means that we started exactly at the cursor and did at
-                    // exactly one iteration. Why exactly one? Because we may
-                    // start at our cursor but do many if our cursor is exactly
-                    // on an emoji.
-                    if (self.i == cursor_x and j == self.i + 1) break;
-
-                    // Before: up to and not including the cursor. This means
-                    // that we started before the cursor (self.i < cursor_x)
-                    // and j is now at the cursor meaning we haven't yet processed
-                    // the cursor.
-                    if (self.i < cursor_x and j == cursor_x) {
-                        assert(j > 0);
-                        break;
+            if (self.break_config.cursor) {
+                // If our cursor is on this line then we break the run around the
+                // cursor. This means that any row with a cursor has at least
+                // three breaks: before, exactly the cursor, and after.
+                //
+                // We do not break a cell that is exactly the grapheme. If there
+                // are cells following that contain joiners, we allow those to
+                // break. This creates an effect where hovering over an emoji
+                // such as a skin-tone emoji is fine, but hovering over the
+                // joiners will show the joiners allowing you to modify the
+                // emoji.
+                if (!cell.hasGrapheme()) {
+                    if (self.cursor_x) |cursor_x| {
+                        // Exactly: self.i is the cursor and we iterated once. This
+                        // means that we started exactly at the cursor and did at
+                        // exactly one iteration. Why exactly one? Because we may
+                        // start at our cursor but do many if our cursor is exactly
+                        // on an emoji.
+                        if (self.i == cursor_x and j == self.i + 1) break;
+
+                        // Before: up to and not including the cursor. This means
+                        // that we started before the cursor (self.i < cursor_x)
+                        // and j is now at the cursor meaning we haven't yet processed
+                        // the cursor.
+                        if (self.i < cursor_x and j == cursor_x) {
+                            assert(j > 0);
+                            break;
+                        }
+
+                        // After: after the cursor. We don't need to do anything
+                        // special, we just let the run complete.
                     }
-
-                    // After: after the cursor. We don't need to do anything
-                    // special, we just let the run complete.
                 }
             }
 
diff --git a/src/font/shaper/web_canvas.zig b/src/font/shaper/web_canvas.zig
index f38ab885ab..95e220b843 100644
--- a/src/font/shaper/web_canvas.zig
+++ b/src/font/shaper/web_canvas.zig
@@ -4,6 +4,7 @@ const Allocator = std.mem.Allocator;
 const ziglyph = @import("ziglyph");
 const font = @import("../main.zig");
 const terminal = @import("../../terminal/main.zig");
+const config = @import("../../config.zig");
 
 const log = std.log.scoped(.font_shaper);
 
@@ -65,6 +66,7 @@ pub const Shaper = struct {
         row: terminal.Screen.Row,
         selection: ?terminal.Selection,
         cursor_x: ?usize,
+        break_config: config.FontShapingBreak,
     ) font.shape.RunIterator {
         return .{
             .hooks = .{ .shaper = self },
@@ -72,6 +74,7 @@ pub const Shaper = struct {
             .row = row,
             .selection = selection,
             .cursor_x = cursor_x,
+            .break_config = break_config,
         };
     }
 
diff --git a/src/renderer/Metal.zig b/src/renderer/Metal.zig
index 52a5437c66..26584b2790 100644
--- a/src/renderer/Metal.zig
+++ b/src/renderer/Metal.zig
@@ -374,6 +374,7 @@ pub const DerivedConfig = struct {
     font_thicken_strength: u8,
     font_features: std.ArrayListUnmanaged([:0]const u8),
     font_styles: font.CodepointResolver.StyleStatus,
+    font_shaping_break: configpkg.FontShapingBreak,
     cursor_color: ?terminal.color.RGB,
     cursor_invert: bool,
     cursor_opacity: f64,
@@ -427,6 +428,7 @@ pub const DerivedConfig = struct {
             .font_thicken_strength = config.@"font-thicken-strength",
             .font_features = font_features.list,
             .font_styles = font_styles,
+            .font_shaping_break = config.@"font-shaping-break",
 
             .cursor_color = if (!cursor_invert and config.@"cursor-color" != null)
                 config.@"cursor-color".?.toTerminalRGB()
@@ -2493,6 +2495,7 @@ fn rebuildCells(
             row,
             row_selection,
             if (shape_cursor) screen.cursor.x else null,
+            self.config.font_shaping_break,
         );
         var shaper_run: ?font.shape.TextRun = try run_iter.next(self.alloc);
         var shaper_cells: ?[]const font.shape.Cell = null;
diff --git a/src/renderer/OpenGL.zig b/src/renderer/OpenGL.zig
index 3e674c7155..4160ed8bc4 100644
--- a/src/renderer/OpenGL.zig
+++ b/src/renderer/OpenGL.zig
@@ -275,6 +275,7 @@ pub const DerivedConfig = struct {
     font_thicken_strength: u8,
     font_features: std.ArrayListUnmanaged([:0]const u8),
     font_styles: font.CodepointResolver.StyleStatus,
+    font_shaping_break: configpkg.FontShapingBreak,
     cursor_color: ?terminal.color.RGB,
     cursor_invert: bool,
     cursor_text: ?terminal.color.RGB,
@@ -325,6 +326,7 @@ pub const DerivedConfig = struct {
             .font_thicken_strength = config.@"font-thicken-strength",
             .font_features = font_features.list,
             .font_styles = font_styles,
+            .font_shaping_break = config.@"font-shaping-break",
 
             .cursor_color = if (!cursor_invert and config.@"cursor-color" != null)
                 config.@"cursor-color".?.toTerminalRGB()
@@ -1349,6 +1351,7 @@ pub fn rebuildCells(
             row,
             row_selection,
             if (shape_cursor) screen.cursor.x else null,
+            self.config.font_shaping_break,
         );
         var shaper_run: ?font.shape.TextRun = try run_iter.next(self.alloc);
         var shaper_cells: ?[]const font.shape.Cell = null;