From beb961fb809ce0bb7dbb8c4ae243b19502742ed0 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          |  31 +++++
 src/font/shaper/coretext.zig   | 231 ++++++++++++++++++++++++++-------
 src/font/shaper/harfbuzz.zig   | 226 +++++++++++++++++++++++++-------
 src/font/shaper/noop.zig       |   3 +
 src/font/shaper/run.zig        |  61 +++++----
 src/font/shaper/web_canvas.zig |   3 +
 7 files changed, 436 insertions(+), 120 deletions(-)

diff --git a/src/config.zig b/src/config.zig
index 7f390fb08..ac38eb89c 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -20,6 +20,7 @@ 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 14ab5219d..ef8f48ee9 100644
--- a/src/config/Config.zig
+++ b/src/config/Config.zig
@@ -270,6 +270,32 @@ pub const compatibility = std.StaticStringMap(
 /// This is currently only supported on macOS.
 @"font-thicken-strength": u8 = 255,
 
+/// Locations to break font shaping into multiple runs.
+///
+/// A "run" is a contiguous segment of text that is shaped together. "Shaping"
+/// is the process of converting text (codepoints) into glyphs (renderable
+/// characters). This is how ligatures are formed, among other things.
+/// For example, if a coding font turns "!=" into a single glyph, then it
+/// must see "!" and "=" next to each other in a single run. When a run
+/// is broken, the text is shaped separately. To continue our example, if
+/// "!" is at the end of one run and "=" is at the start of the next run,
+/// then the ligature will not be formed.
+///
+/// Ghostty breaks runs at certain points to improve readability or usability.
+/// For example, Ghostty by default will break runs under the cursor so that
+/// text editing can see the individual characters rather than a ligature.
+/// This configuration lets you configure this behavior.
+///
+/// Combine values with a comma to set multiple options. Prefix an
+/// option with "no-" to disable it. Enabling and disabling options
+/// can be done at the same time.
+///
+/// Available options:
+///
+///   * `cursor` - Break runs under the cursor.
+///
+@"font-shaping-break": FontShapingBreak = .{},
+
 /// What color space to use when performing alpha blending.
 ///
 /// This affects the appearance of text and of any images with transparency.
@@ -6214,6 +6240,11 @@ 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 8e2c45c69..654af02d9 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| {
@@ -1046,6 +1063,7 @@ test "shape emoji width long" {
         screen.pages.pin(.{ .screen = .{ .y = 1 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1082,6 +1100,7 @@ test "shape variation selector VS15" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1117,6 +1136,7 @@ test "shape variation selector VS16" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1149,6 +1169,7 @@ 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| {
@@ -1187,6 +1208,7 @@ test "shape Chinese characters" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1227,6 +1249,7 @@ test "shape box glyphs" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -1267,6 +1290,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1290,6 +1314,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1313,6 +1338,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1336,6 +1362,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1359,6 +1386,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1391,6 +1419,7 @@ test "shape cursor boundary" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1400,61 +1429,126 @@ 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
     {
-        // Get our run iterator
-        var shaper = &testdata.shaper;
-        var it = shaper.runIterator(
-            testdata.grid,
-            &screen,
-            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
-            null,
-            1,
-        );
-        var count: usize = 0;
-        while (try it.next(alloc)) |run| {
-            count += 1;
-            _ = try shaper.shape(run);
+        // 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);
         }
-        try testing.expectEqual(@as(usize, 3), 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,
-        );
-        var count: usize = 0;
-        while (try it.next(alloc)) |run| {
-            count += 1;
-            _ = try shaper.shape(run);
+        // 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);
         }
-        try testing.expectEqual(@as(usize, 2), count);
     }
 }
 
@@ -1480,6 +1574,7 @@ test "shape cursor boundary and colored emoji" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1499,6 +1594,25 @@ test "shape cursor boundary and colored emoji" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             0,
+            .{},
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 1), count);
+    }
+    {
+        // 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| {
@@ -1516,6 +1630,25 @@ test "shape cursor boundary and colored emoji" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             1,
+            .{},
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 1), count);
+    }
+    {
+        // 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| {
@@ -1546,6 +1679,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1570,6 +1704,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1595,6 +1730,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1620,6 +1756,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1644,6 +1781,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1684,6 +1822,7 @@ 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 361cbbe93..56654e88f 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| {
@@ -571,6 +584,7 @@ test "shape emoji width long" {
         screen.pages.pin(.{ .screen = .{ .y = 1 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -609,6 +623,7 @@ test "shape variation selector VS15" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -646,6 +661,7 @@ test "shape variation selector VS16" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -680,6 +696,7 @@ 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| {
@@ -718,6 +735,7 @@ test "shape Chinese characters" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -758,6 +776,7 @@ test "shape box glyphs" {
         screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
         null,
         null,
+        .{},
     );
     var count: usize = 0;
     while (try it.next(alloc)) |run| {
@@ -799,6 +818,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -822,6 +842,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -845,6 +866,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -868,6 +890,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -891,6 +914,7 @@ test "shape selection boundary" {
                 false,
             ),
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -923,6 +947,7 @@ test "shape cursor boundary" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -932,61 +957,126 @@ 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
     {
-        // Get our run iterator
-        var shaper = &testdata.shaper;
-        var it = shaper.runIterator(
-            testdata.grid,
-            &screen,
-            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
-            null,
-            1,
-        );
-        var count: usize = 0;
-        while (try it.next(alloc)) |run| {
-            count += 1;
-            _ = try shaper.shape(run);
+        // 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);
         }
-        try testing.expectEqual(@as(usize, 3), 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,
-        );
-        var count: usize = 0;
-        while (try it.next(alloc)) |run| {
-            count += 1;
-            _ = try shaper.shape(run);
+        // 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);
         }
-        try testing.expectEqual(@as(usize, 2), count);
     }
 }
 
@@ -1012,6 +1102,7 @@ test "shape cursor boundary and colored emoji" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1031,6 +1122,25 @@ test "shape cursor boundary and colored emoji" {
             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, 1), count);
+    }
+    {
+        // 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| {
@@ -1048,6 +1158,25 @@ test "shape cursor boundary and colored emoji" {
             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, 1), count);
+    }
+    {
+        // 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| {
@@ -1078,6 +1207,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1102,6 +1232,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1127,6 +1258,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1152,6 +1284,7 @@ test "shape cell attribute change" {
             screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
             null,
             null,
+            .{},
         );
         var count: usize = 0;
         while (try it.next(alloc)) |run| {
@@ -1176,6 +1309,7 @@ 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 f8988f4ee..1041954e6 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 18ddd4b56..a6ff79e39 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;
+            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;
+                        // 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 f38ab885a..95e220b84 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,
         };
     }