From 05470bb36a11f5cbaefb141fbaa5f67a37dcb1bd Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Fri, 8 Mar 2024 09:58:19 -0800
Subject: [PATCH] font/shaper: new API

---
 src/font/shaper/harfbuzz.zig | 224 ++++++++++++++++++++---------------
 src/font/shaper/run.zig      |  24 ++--
 src/terminal2/PageList.zig   |   9 ++
 3 files changed, 149 insertions(+), 108 deletions(-)

diff --git a/src/font/shaper/harfbuzz.zig b/src/font/shaper/harfbuzz.zig
index 17a09c3ad..29a7e315f 100644
--- a/src/font/shaper/harfbuzz.zig
+++ b/src/font/shaper/harfbuzz.zig
@@ -1047,103 +1047,133 @@ test "shape cursor boundary and colored emoji" {
     }
 }
 
-// test "shape cell attribute change" {
-//     const testing = std.testing;
-//     const alloc = testing.allocator;
-//
-//     var testdata = try testShaper(alloc);
-//     defer testdata.deinit();
-//
-//     // Plain >= should shape into 1 run
-//     {
-//         var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-//         defer screen.deinit();
-//         try screen.testWriteString(">=");
-//
-//         var shaper = &testdata.shaper;
-//         var it = shaper.runIterator(testdata.cache, screen.getRow(.{ .screen = 0 }), null, null);
-//         var count: usize = 0;
-//         while (try it.next(alloc)) |run| {
-//             count += 1;
-//             _ = try shaper.shape(run);
-//         }
-//         try testing.expectEqual(@as(usize, 1), count);
-//     }
-//
-//     // Bold vs regular should split
-//     {
-//         var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-//         defer screen.deinit();
-//         try screen.testWriteString(">");
-//         screen.cursor.pen.attrs.bold = true;
-//         try screen.testWriteString("=");
-//
-//         var shaper = &testdata.shaper;
-//         var it = shaper.runIterator(testdata.cache, screen.getRow(.{ .screen = 0 }), null, null);
-//         var count: usize = 0;
-//         while (try it.next(alloc)) |run| {
-//             count += 1;
-//             _ = try shaper.shape(run);
-//         }
-//         try testing.expectEqual(@as(usize, 2), count);
-//     }
-//
-//     // Changing fg color should split
-//     {
-//         var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-//         defer screen.deinit();
-//         screen.cursor.pen.fg = .{ .rgb = .{ .r = 1, .g = 2, .b = 3 } };
-//         try screen.testWriteString(">");
-//         screen.cursor.pen.fg = .{ .rgb = .{ .r = 3, .g = 2, .b = 1 } };
-//         try screen.testWriteString("=");
-//
-//         var shaper = &testdata.shaper;
-//         var it = shaper.runIterator(testdata.cache, screen.getRow(.{ .screen = 0 }), null, null);
-//         var count: usize = 0;
-//         while (try it.next(alloc)) |run| {
-//             count += 1;
-//             _ = try shaper.shape(run);
-//         }
-//         try testing.expectEqual(@as(usize, 2), count);
-//     }
-//
-//     // Changing bg color should split
-//     {
-//         var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-//         defer screen.deinit();
-//         screen.cursor.pen.bg = .{ .rgb = .{ .r = 1, .g = 2, .b = 3 } };
-//         try screen.testWriteString(">");
-//         screen.cursor.pen.bg = .{ .rgb = .{ .r = 3, .g = 2, .b = 1 } };
-//         try screen.testWriteString("=");
-//
-//         var shaper = &testdata.shaper;
-//         var it = shaper.runIterator(testdata.cache, screen.getRow(.{ .screen = 0 }), null, null);
-//         var count: usize = 0;
-//         while (try it.next(alloc)) |run| {
-//             count += 1;
-//             _ = try shaper.shape(run);
-//         }
-//         try testing.expectEqual(@as(usize, 2), count);
-//     }
-//
-//     // Same bg color should not split
-//     {
-//         var screen = try terminal.Screen.init(alloc, 3, 10, 0);
-//         defer screen.deinit();
-//         screen.cursor.pen.bg = .{ .rgb = .{ .r = 1, .g = 2, .b = 3 } };
-//         try screen.testWriteString(">");
-//         try screen.testWriteString("=");
-//
-//         var shaper = &testdata.shaper;
-//         var it = shaper.runIterator(testdata.cache, screen.getRow(.{ .screen = 0 }), null, null);
-//         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 cell attribute change" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var testdata = try testShaper(alloc);
+    defer testdata.deinit();
+
+    // Plain >= should shape into 1 run
+    {
+        var screen = try terminal.Screen.init(alloc, 10, 3, 0);
+        defer screen.deinit();
+        try screen.testWriteString(">=");
+
+        var shaper = &testdata.shaper;
+        var it = shaper.runIterator(
+            testdata.cache,
+            &screen,
+            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+            null,
+            null,
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 1), count);
+    }
+
+    // Bold vs regular should split
+    {
+        var screen = try terminal.Screen.init(alloc, 3, 10, 0);
+        defer screen.deinit();
+        try screen.testWriteString(">");
+        try screen.setAttribute(.{ .bold = {} });
+        try screen.testWriteString("=");
+
+        var shaper = &testdata.shaper;
+        var it = shaper.runIterator(
+            testdata.cache,
+            &screen,
+            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+            null,
+            null,
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 2), count);
+    }
+
+    // Changing fg color should split
+    {
+        var screen = try terminal.Screen.init(alloc, 3, 10, 0);
+        defer screen.deinit();
+        try screen.setAttribute(.{ .direct_color_fg = .{ .r = 1, .g = 2, .b = 3 } });
+        try screen.testWriteString(">");
+        try screen.setAttribute(.{ .direct_color_fg = .{ .r = 3, .g = 2, .b = 1 } });
+        try screen.testWriteString("=");
+
+        var shaper = &testdata.shaper;
+        var it = shaper.runIterator(
+            testdata.cache,
+            &screen,
+            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+            null,
+            null,
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 2), count);
+    }
+
+    // Changing bg color should split
+    {
+        var screen = try terminal.Screen.init(alloc, 3, 10, 0);
+        defer screen.deinit();
+        try screen.setAttribute(.{ .direct_color_bg = .{ .r = 1, .g = 2, .b = 3 } });
+        try screen.testWriteString(">");
+        try screen.setAttribute(.{ .direct_color_bg = .{ .r = 3, .g = 2, .b = 1 } });
+        try screen.testWriteString("=");
+
+        var shaper = &testdata.shaper;
+        var it = shaper.runIterator(
+            testdata.cache,
+            &screen,
+            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+            null,
+            null,
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 2), count);
+    }
+
+    // Same bg color should not split
+    {
+        var screen = try terminal.Screen.init(alloc, 3, 10, 0);
+        defer screen.deinit();
+        try screen.setAttribute(.{ .direct_color_bg = .{ .r = 1, .g = 2, .b = 3 } });
+        try screen.testWriteString(">");
+        try screen.testWriteString("=");
+
+        var shaper = &testdata.shaper;
+        var it = shaper.runIterator(
+            testdata.cache,
+            &screen,
+            screen.pages.pin(.{ .screen = .{ .y = 0 } }).?,
+            null,
+            null,
+        );
+        var count: usize = 0;
+        while (try it.next(alloc)) |run| {
+            count += 1;
+            _ = try shaper.shape(run);
+        }
+        try testing.expectEqual(@as(usize, 1), count);
+    }
+}
 
 const TestShaper = struct {
     alloc: Allocator,
diff --git a/src/font/shaper/run.zig b/src/font/shaper/run.zig
index b98f0fd49..7a6c4e554 100644
--- a/src/font/shaper/run.zig
+++ b/src/font/shaper/run.zig
@@ -54,6 +54,9 @@ pub const RunIterator = struct {
         // Allow the hook to prepare
         try self.hooks.prepare();
 
+        // Let's get our style that we'll expect for the run.
+        const style = self.row.style(&cells[0]);
+
         // Go through cell by cell and accumulate while we build our run.
         var j: usize = self.i;
         while (j < max) : (j += 1) {
@@ -92,14 +95,13 @@ pub const RunIterator = struct {
 
             // Text runs break when font styles change so we need to get
             // the proper style.
-            const style: font.Style = style: {
-                // TODO(paged-terminal)
-                // if (cell.attrs.bold) {
-                //     if (cell.attrs.italic) break :style .bold_italic;
-                //     break :style .bold;
-                // }
-                //
-                // if (cell.attrs.italic) break :style .italic;
+            const font_style: font.Style = style: {
+                if (style.flags.bold) {
+                    if (style.flags.italic) break :style .bold_italic;
+                    break :style .bold;
+                }
+
+                if (style.flags.italic) break :style .italic;
                 break :style .regular;
             };
 
@@ -166,7 +168,7 @@ pub const RunIterator = struct {
                 if (try self.indexForCell(
                     alloc,
                     cell,
-                    style,
+                    font_style,
                     presentation,
                 )) |idx| break :font_info .{ .idx = idx };
 
@@ -175,7 +177,7 @@ pub const RunIterator = struct {
                 if (try self.group.indexForCodepoint(
                     alloc,
                     0xFFFD, // replacement char
-                    style,
+                    font_style,
                     presentation,
                 )) |idx| break :font_info .{ .idx = idx, .fallback = 0xFFFD };
 
@@ -183,7 +185,7 @@ pub const RunIterator = struct {
                 if (try self.group.indexForCodepoint(
                     alloc,
                     ' ',
-                    style,
+                    font_style,
                     presentation,
                 )) |idx| break :font_info .{ .idx = idx, .fallback = ' ' };
 
diff --git a/src/terminal2/PageList.zig b/src/terminal2/PageList.zig
index dc72bb881..fb4005991 100644
--- a/src/terminal2/PageList.zig
+++ b/src/terminal2/PageList.zig
@@ -2059,6 +2059,15 @@ pub const Pin = struct {
         return self.page.data.lookupGrapheme(cell);
     }
 
+    /// Returns the style for the given cell in this pin.
+    pub fn style(self: Pin, cell: *pagepkg.Cell) stylepkg.Style {
+        if (cell.style_id == stylepkg.default_id) return .{};
+        return self.page.data.styles.lookupId(
+            self.page.data.memory,
+            cell.style_id,
+        ).?.*;
+    }
+
     /// Iterators. These are the same as PageList iterator funcs but operate
     /// on pins rather than points. This is MUCH more efficient than calling
     /// pointFromPin and building up the iterator from points.