terminal: set left and right margins, left and right margin mode 69

src/terminal/Terminal.zig

@@ -1801,6 +1801,23 @@ pub fn setTopAndBottomMargin(self: *Terminal, top_req: usize, bottom_req: usize)
     self.setCursorPos(1, 1);
 }
 
+/// DECSLRM
+pub fn setLeftAndRightMargin(self: *Terminal, left_req: usize, right_req: usize) void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    // We must have this mode enabled to do anything
+    if (!self.modes.get(.enable_left_and_right_margin)) return;
+
+    const left = @max(1, left_req);
+    const right = @min(self.rows, if (right_req == 0) self.rows else right_req);
+    if (left >= right) return;
+
+    self.scrolling_region.left = left - 1;
+    self.scrolling_region.right = right - 1;
+    self.setCursorPos(1, 1);
+}
+
 /// Mark the current semantic prompt information. Current escape sequences
 /// (OSC 133) only allow setting this for wherever the current active cursor
 /// is located.
@@ -2637,6 +2654,126 @@ test "Terminal: setTopAndBottomMargin top equal to bottom" {
         try testing.expectEqualStrings("\nABC\nDEF\nGHI", str);
     }
 }
+
+test "Terminal: setLeftAndRightMargin simple" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    try t.printString("ABC");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("DEF");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("GHI");
+    t.modes.set(.enable_left_and_right_margin, true);
+    t.setLeftAndRightMargin(0, 0);
+    t.eraseChars(1);
+
+    {
+        var str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings(" BC\nDEF\nGHI", str);
+    }
+}
+
+test "Terminal: setLeftAndRightMargin left only" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    try t.printString("ABC");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("DEF");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("GHI");
+    t.modes.set(.enable_left_and_right_margin, true);
+    t.setLeftAndRightMargin(2, 0);
+    t.setCursorPos(1, 2);
+    try t.insertLines(1);
+
+    {
+        var str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings("A\nDBC\nGEF\n HI", str);
+    }
+}
+
+test "Terminal: setLeftAndRightMargin left and right" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    try t.printString("ABC");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("DEF");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("GHI");
+    t.modes.set(.enable_left_and_right_margin, true);
+    t.setLeftAndRightMargin(1, 2);
+    t.setCursorPos(1, 2);
+    try t.insertLines(1);
+
+    {
+        var str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings("  C\nABF\nDEI\nGH", str);
+    }
+}
+
+test "Terminal: setLeftAndRightMargin left equal right" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    try t.printString("ABC");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("DEF");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("GHI");
+    t.modes.set(.enable_left_and_right_margin, true);
+    t.setLeftAndRightMargin(2, 2);
+    t.setCursorPos(1, 2);
+    try t.insertLines(1);
+
+    {
+        var str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings("\nABC\nDEF\nGHI", str);
+    }
+}
+
+test "Terminal: setLeftAndRightMargin mode 69 unset" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    try t.printString("ABC");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("DEF");
+    t.carriageReturn();
+    try t.linefeed();
+    try t.printString("GHI");
+    t.modes.set(.enable_left_and_right_margin, false);
+    t.setLeftAndRightMargin(1, 2);
+    t.setCursorPos(1, 2);
+    try t.insertLines(1);
+
+    {
+        var str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings("\nABC\nDEF\nGHI", str);
+    }
+}
+
 test "Terminal: deleteLines" {
     const alloc = testing.allocator;
     var t = try init(alloc, 80, 80);

src/terminal/modes.zig

@@ -134,10 +134,12 @@ const ModeTag = packed struct(u16) {
 
 pub fn modeFromInt(v: u16, ansi: bool) ?Mode {
     inline for (entries) |entry| {
-        if (entry.value == v and entry.ansi == ansi) {
+        if (comptime !entry.disabled) {
-            const tag: ModeTag = .{ .ansi = ansi, .value = entry.value };
+            if (entry.value == v and entry.ansi == ansi) {
-            const int: ModeTag.Backing = @bitCast(tag);
+                const tag: ModeTag = .{ .ansi = ansi, .value = entry.value };
-            return @enumFromInt(int);
+                const int: ModeTag.Backing = @bitCast(tag);
+                return @enumFromInt(int);
+            }
         }
     }
 
@@ -160,6 +162,7 @@ const ModeEntry = struct {
     value: comptime_int,
     default: bool = false,
     ansi: bool = false,
+    disabled: bool = false,
 };
 
 /// The full list of available entries. For documentation see how
@@ -195,6 +198,10 @@ const entries: []const ModeEntry = &.{
     .{ .name = "bracketed_paste", .value = 2004 },
     .{ .name = "synchronized_output", .value = 2026 },
     .{ .name = "grapheme_cluster", .value = 2027 },
+
+    // Disabled for now until we ensure we get left/right margins working
+    // correctly in all sequences.
+    .{ .name = "enable_left_and_right_margin", .value = 69, .disabled = true },
 };
 
 test {

src/terminal/stream.zig

@@ -787,8 +787,20 @@ pub fn Stream(comptime Handler: type) type {
                     ),
                 },
 
-                // Save Mode
                 's' => switch (action.intermediates.len) {
+                    // DECSLRM
+                    0 => if (@hasDecl(T, "setLeftAndRightMargin")) {
+                        switch (action.params.len) {
+                            0 => try self.handler.setLeftAndRightMargin(0, 0),
+                            1 => try self.handler.setLeftAndRightMargin(action.params[0], 0),
+                            2 => try self.handler.setLeftAndRightMargin(action.params[0], action.params[1]),
+                            else => log.warn("invalid DECSLRM command: {}", .{action}),
+                        }
+                    } else log.warn(
+                        "unimplemented CSI callback: {}",
+                        .{action},
+                    ),
+
                     1 => switch (action.intermediates[0]) {
                         '?' => if (@hasDecl(T, "saveMode")) {
                             for (action.params) |mode_int| {

src/termio/Exec.zig

@@ -1397,6 +1397,10 @@ const StreamHandler = struct {
         self.terminal.setTopAndBottomMargin(top, bot);
     }
 
+    pub fn setLeftAndRightMargin(self: *StreamHandler, left: u16, right: u16) !void {
+        self.terminal.setLeftAndRightMargin(left, right);
+    }
+
     pub fn setModifyKeyFormat(self: *StreamHandler, format: terminal.ModifyKeyFormat) !void {
         self.terminal.flags.modify_other_keys_2 = false;
         switch (format) {
@@ -1460,6 +1464,13 @@ const StreamHandler = struct {
             // Origin resets cursor pos
             .origin => self.terminal.setCursorPos(1, 1),
 
+            .enable_left_and_right_margin => if (!enabled) {
+                // When we disable left/right margin mode we need to
+                // reset the left/right margins.
+                self.terminal.scrolling_region.left = 0;
+                self.terminal.scrolling_region.right = self.terminal.cols - 1;
+            },
+
             .alt_screen_save_cursor_clear_enter => {
                 const opts: terminal.Terminal.AlternateScreenOptions = .{
                     .cursor_save = true,