Merge pull request #58 from mitchellh/underline-styles

Underline styles: singe, double, dashed, dotted, curly

src/Window.zig

@@ -289,13 +289,6 @@ pub fn create(alloc: Allocator, app: *App, config: *const Config) !*Window {
     // Pre-calculate our initial cell size ourselves.
     const cell_size = try renderer.CellSize.init(alloc, font_group);
 
-    // Setup our box font
-    font_group.group.sprite = font.sprite.Face{
-        .width = @floatToInt(u32, cell_size.width),
-        .height = @floatToInt(u32, cell_size.height),
-        .thickness = 2,
-    };
-
     // Convert our padding from points to pixels
     const padding_x = (@intToFloat(f32, config.@"window-padding-x") * x_dpi) / 72;
     const padding_y = (@intToFloat(f32, config.@"window-padding-y") * y_dpi) / 72;

src/font/main.zig

@@ -11,6 +11,7 @@ pub const Glyph = @import("Glyph.zig");
 pub const Library = @import("Library.zig");
 pub const Shaper = @import("Shaper.zig");
 pub const sprite = @import("sprite.zig");
+pub const Sprite = sprite.Sprite;
 pub const Descriptor = discovery.Descriptor;
 pub const Discover = discovery.Discover;
 
@@ -60,6 +61,9 @@ pub const Presentation = enum(u1) {
     emoji = 1, // U+FEOF
 };
 
+/// A FontIndex that can be used to use the sprite font directly.
+pub const sprite_index = Group.FontIndex.initSpecial(.sprite);
+
 test {
     @import("std").testing.refAllDecls(@This());
 }

src/font/sprite.zig

@@ -11,10 +11,14 @@ pub const Face = @import("sprite/Face.zig");
 /// Area of Unicode.
 pub const Sprite = enum(u32) {
     // Start 1 above the maximum Unicode codepoint.
-    const start: u32 = std.math.maxInt(u21) + 1;
-    const end: u32 = std.math.maxInt(u32);
+    pub const start: u32 = std.math.maxInt(u21) + 1;
+    pub const end: u32 = std.math.maxInt(u32);
 
     underline = start,
+    underline_double = start + 1,
+    underline_dotted = start + 2,
+    underline_dashed = start + 3,
+    underline_curly = start + 4,
 
     // Note: we don't currently put the box drawing glyphs in here because
     // there are a LOT and I'm lazy. What I want to do is spend more time

src/font/sprite/Canvas.zig

@@ -117,13 +117,13 @@ pub fn writeAtlas(self: *Canvas, alloc: Allocator, atlas: *Atlas) !Atlas.Region
 
 /// Draw and fill a rectangle. This is the main primitive for drawing
 /// lines as well (which are just generally skinny rectangles...)
-pub fn rect(self: *Canvas, v: Rect, color: pixman.Color) void {
+pub fn rect(self: *Canvas, v: Rect, color: Color) void {
     const boxes = &[_]pixman.Box32{
         .{
             .x1 = @intCast(i32, v.x),
             .y1 = @intCast(i32, v.y),
-            .x2 = @intCast(i32, v.width),
-            .y2 = @intCast(i32, v.height),
+            .x2 = @intCast(i32, v.x + v.width),
+            .y2 = @intCast(i32, v.y + v.height),
         },
     };
 

src/font/sprite/Face.zig

@@ -17,8 +17,10 @@ const builtin = @import("builtin");
 const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const font = @import("../main.zig");
+const Sprite = font.sprite.Sprite;
 const Atlas = @import("../../Atlas.zig");
 const Box = @import("Box.zig");
+const underline = @import("underline.zig");
 
 /// The cell width and height.
 width: u32,
@@ -28,6 +30,9 @@ height: u32,
 /// want to do any DPI scaling, it is expected to be done earlier.
 thickness: u32,
 
+/// The position fo the underline.
+underline_position: u32 = 0,
+
 /// Returns true if the codepoint exists in our sprite font.
 pub fn hasCodepoint(self: Face, cp: u32, p: ?font.Presentation) bool {
     // We ignore presentation. No matter what presentation is requested
@@ -47,25 +52,45 @@ pub fn renderGlyph(
     if (std.debug.runtime_safety) assert(self.hasCodepoint(cp, null));
 
     // Safe to ".?" because of the above assertion.
-    switch (Kind.init(cp).?) {
-        .box => {
+    return switch (Kind.init(cp).?) {
+        .box => box: {
             const f: Box = .{
                 .width = self.width,
                 .height = self.height,
                 .thickness = self.thickness,
             };
 
-            return try f.renderGlyph(alloc, atlas, cp);
+            break :box try f.renderGlyph(alloc, atlas, cp);
         },
-    }
+
+        .underline => try underline.renderGlyph(
+            alloc,
+            atlas,
+            @intToEnum(Sprite, cp),
+            self.width,
+            self.height,
+            self.underline_position,
+            self.thickness,
+        ),
+    };
 }
 
 /// Kind of sprites we have. Drawing is implemented separately for each kind.
 const Kind = enum {
     box,
+    underline,
 
     pub fn init(cp: u32) ?Kind {
         return switch (cp) {
+            Sprite.start...Sprite.end => switch (@intToEnum(Sprite, cp)) {
+                .underline,
+                .underline_double,
+                .underline_dotted,
+                .underline_dashed,
+                .underline_curly,
+                => .underline,
+            },
+
             // Box fonts
             0x2500...0x257F, // "Box Drawing" block
             0x2580...0x259F, // "Block Elements" block

src/font/sprite/underline.zig

@@ -0,0 +1,205 @@
+//! This file renders underline sprites. To draw underlines, we render the
+//! full cell-width as a sprite and then draw it as a separate pass to the
+//! text.
+//!
+//! We used to render the underlines directly in the GPU shaders but its
+//! annoying to support multiple types of underlines and its also annoying
+//! to maintain and debug another set of shaders for each renderer instead of
+//! just relying on the glyph system we already need to support for text
+//! anyways.
+const std = @import("std");
+const builtin = @import("builtin");
+const assert = std.debug.assert;
+const Allocator = std.mem.Allocator;
+const font = @import("../main.zig");
+const Sprite = font.sprite.Sprite;
+const Atlas = @import("../../Atlas.zig");
+
+/// Draw an underline.
+pub fn renderGlyph(
+    alloc: Allocator,
+    atlas: *Atlas,
+    sprite: Sprite,
+    width: u32,
+    height: u32,
+    line_pos: u32,
+    line_thickness: u32,
+) !font.Glyph {
+    // Create the canvas we'll use to draw. We draw the underline in
+    // a full cell size and position it according to "pos".
+    var canvas = try font.sprite.Canvas.init(alloc, width, height);
+    defer canvas.deinit(alloc);
+
+    // Perform the actual drawing
+    (Draw{
+        .width = width,
+        .height = height,
+        .pos = line_pos,
+        .thickness = line_thickness,
+    }).draw(&canvas, sprite);
+
+    // Write the drawing to the atlas
+    const region = try canvas.writeAtlas(alloc, atlas);
+
+    // Our coordinates start at the BOTTOM for our renderers so we have to
+    // specify an offset of the full height because we rendered a full size
+    // cell.
+    const offset_y = @intCast(i32, height);
+
+    return font.Glyph{
+        .width = width,
+        .height = height,
+        .offset_x = 0,
+        .offset_y = offset_y,
+        .atlas_x = region.x,
+        .atlas_y = region.y,
+        .advance_x = @intToFloat(f32, width),
+    };
+}
+
+/// Stores drawing state.
+const Draw = struct {
+    width: u32,
+    height: u32,
+    pos: u32,
+    thickness: u32,
+
+    /// Draw a specific underline sprite to the canvas.
+    fn draw(self: Draw, canvas: *font.sprite.Canvas, sprite: Sprite) void {
+        switch (sprite) {
+            .underline => self.drawSingle(canvas),
+            .underline_double => self.drawDouble(canvas),
+            .underline_dotted => self.drawDotted(canvas),
+            .underline_dashed => self.drawDashed(canvas),
+            .underline_curly => self.drawCurly(canvas),
+        }
+    }
+
+    /// Draw a single underline.
+    fn drawSingle(self: Draw, canvas: *font.sprite.Canvas) void {
+        canvas.rect(.{
+            .x = 0,
+            .y = self.pos,
+            .width = self.width,
+            .height = self.thickness,
+        }, .on);
+    }
+
+    /// Draw a double underline.
+    fn drawDouble(self: Draw, canvas: *font.sprite.Canvas) void {
+        canvas.rect(.{
+            .x = 0,
+            .y = self.pos,
+            .width = self.width,
+            .height = self.thickness,
+        }, .on);
+
+        canvas.rect(.{
+            .x = 0,
+            .y = self.pos + (self.thickness * 2),
+            .width = self.width,
+            .height = self.thickness,
+        }, .on);
+    }
+
+    /// Draw a dotted underline.
+    fn drawDotted(self: Draw, canvas: *font.sprite.Canvas) void {
+        const dot_width = @max(self.thickness, 3);
+        const dot_count = self.width / dot_width;
+        var i: u32 = 0;
+        while (i < dot_count) : (i += 2) {
+            canvas.rect(.{
+                .x = i * dot_width,
+                .y = self.pos,
+                .width = dot_width,
+                .height = self.thickness,
+            }, .on);
+        }
+    }
+
+    /// Draw a dashed underline.
+    fn drawDashed(self: Draw, canvas: *font.sprite.Canvas) void {
+        const dash_width = self.width / 3 + 1;
+        const dash_count = (self.width / dash_width) + 1;
+        var i: u32 = 0;
+        while (i < dash_count) : (i += 2) {
+            canvas.rect(.{
+                .x = i * dash_width,
+                .y = self.pos,
+                .width = dash_width,
+                .height = self.thickness,
+            }, .on);
+        }
+    }
+
+    /// Draw a curly underline. Thanks to Wez Furlong for providing
+    /// the basic math structure for this since I was lazy with the
+    /// geometry.
+    fn drawCurly(self: Draw, canvas: *font.sprite.Canvas) void {
+        // This is the lowest that the curl can go.
+        const y_max = self.height - 1;
+
+        // The full heightof the wave can be from the bottom to the
+        // underline position. We also calculate our starting y which is
+        // slightly below our descender since our wave will move about that.
+        const wave_height = @intToFloat(f64, y_max - self.pos);
+        const half_height = wave_height / 4;
+        const y = self.pos + @floatToInt(u32, half_height);
+
+        const x_factor = (2 * std.math.pi) / @intToFloat(f64, self.width);
+        var x: u32 = 0;
+        while (x < self.width) : (x += 1) {
+            const vertical = @floatToInt(
+                u32,
+                (-1 * half_height) * @sin(@intToFloat(f64, x) * x_factor) + half_height,
+            );
+
+            var row: u32 = 0;
+            while (row < self.thickness) : (row += 1) {
+                const y1 = @min(row + y + vertical, y_max);
+                canvas.rect(.{
+                    .x = x,
+                    .y = y1,
+                    .width = 1,
+                    .height = 1,
+                }, .on);
+            }
+        }
+    }
+};
+
+test "single" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var atlas_greyscale = try Atlas.init(alloc, 512, .greyscale);
+    defer atlas_greyscale.deinit(alloc);
+
+    _ = try renderGlyph(
+        alloc,
+        &atlas_greyscale,
+        .underline,
+        36,
+        18,
+        9,
+        2,
+    );
+}
+
+test "curly" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var atlas_greyscale = try Atlas.init(alloc, 512, .greyscale);
+    defer atlas_greyscale.deinit(alloc);
+
+    _ = try renderGlyph(
+        alloc,
+        &atlas_greyscale,
+        .underline_curly,
+        36,
+        18,
+        9,
+        2,
+    );
+}

src/renderer/Metal.zig

@@ -102,8 +102,6 @@ const GPUUniforms = extern struct {
     cell_size: [2]f32,
 
     /// Metrics for underline/strikethrough
-    underline_position: f32,
-    underline_thickness: f32,
     strikethrough_position: f32,
     strikethrough_thickness: f32,
 };
@@ -115,7 +113,6 @@ const GPUCellMode = enum(u8) {
     cursor_rect = 3,
     cursor_rect_hollow = 4,
     cursor_bar = 5,
-    underline = 6,
     strikethrough = 8,
 
     pub fn fromCursor(cursor: renderer.CursorStyle) GPUCellMode {
@@ -171,6 +168,14 @@ pub fn init(alloc: Allocator, options: renderer.Options) !Metal {
     };
     log.debug("cell dimensions={}", .{metrics});
 
+    // Set the sprite font up
+    options.font_group.group.sprite = font.sprite.Face{
+        .width = @floatToInt(u32, metrics.cell_width),
+        .height = @floatToInt(u32, metrics.cell_height),
+        .thickness = 2,
+        .underline_position = @floatToInt(u32, metrics.underline_position),
+    };
+
     // Create the font shaper. We initially create a shaper that can support
     // a width of 160 which is a common width for modern screens to help
     // avoid allocations later.
@@ -259,8 +264,6 @@ pub fn init(alloc: Allocator, options: renderer.Options) !Metal {
         .uniforms = .{
             .projection_matrix = undefined,
             .cell_size = undefined,
-            .underline_position = metrics.underline_position,
-            .underline_thickness = metrics.underline_thickness,
             .strikethrough_position = metrics.strikethrough_position,
             .strikethrough_thickness = metrics.strikethrough_thickness,
         },
@@ -397,8 +400,6 @@ pub fn setFontSize(self: *Metal, size: font.face.DesiredSize) !void {
     self.uniforms = .{
         .projection_matrix = self.uniforms.projection_matrix,
         .cell_size = .{ new_cell_size.width, new_cell_size.height },
-        .underline_position = metrics.underline_position,
-        .underline_thickness = metrics.underline_thickness,
         .strikethrough_position = metrics.strikethrough_position,
         .strikethrough_thickness = metrics.strikethrough_thickness,
     };
@@ -408,11 +409,13 @@ pub fn setFontSize(self: *Metal, size: font.face.DesiredSize) !void {
     if (std.meta.eql(self.cell_size, new_cell_size)) return;
     self.cell_size = new_cell_size;
 
-    // Set the cell size of the box font
-    if (self.font_group.group.sprite) |*sprite| {
-        sprite.width = @floatToInt(u32, self.cell_size.width);
-        sprite.height = @floatToInt(u32, self.cell_size.height);
-    }
+    // Set the sprite font up
+    self.font_group.group.sprite = font.sprite.Face{
+        .width = @floatToInt(u32, self.cell_size.width),
+        .height = @floatToInt(u32, self.cell_size.height),
+        .thickness = 2,
+        .underline_position = @floatToInt(u32, metrics.underline_position),
+    };
 
     // Notify the window that the cell size changed.
     _ = self.window_mailbox.push(.{
@@ -707,8 +710,6 @@ pub fn setScreenSize(self: *Metal, _: renderer.ScreenSize) !void {
             -1 * padding.top,
         ),
         .cell_size = .{ self.cell_size.width, self.cell_size.height },
-        .underline_position = old.underline_position,
-        .underline_thickness = old.underline_thickness,
         .strikethrough_position = old.strikethrough_position,
         .strikethrough_thickness = old.strikethrough_thickness,
     };
@@ -911,12 +912,31 @@ pub fn updateCell(
         });
     }
 
-    if (cell.attrs.underline) {
+    if (cell.attrs.underline != .none) {
+        const sprite: font.Sprite = switch (cell.attrs.underline) {
+            .none => unreachable,
+            .single => .underline,
+            .double => .underline_double,
+            .dotted => .underline_dotted,
+            .dashed => .underline_dashed,
+            .curly => .underline_curly,
+        };
+
+        const glyph = try self.font_group.renderGlyph(
+            self.alloc,
+            font.sprite_index,
+            @enumToInt(sprite),
+            null,
+        );
+
         self.cells.appendAssumeCapacity(.{
-            .mode = .underline,
+            .mode = .fg,
             .grid_pos = .{ @intToFloat(f32, x), @intToFloat(f32, y) },
             .cell_width = cell.widthLegacy(),
             .color = .{ colors.fg.r, colors.fg.g, colors.fg.b, alpha },
+            .glyph_pos = .{ glyph.atlas_x, glyph.atlas_y },
+            .glyph_size = .{ glyph.width, glyph.height },
+            .glyph_offset = .{ glyph.offset_x, glyph.offset_y },
         });
     }
 

src/renderer/OpenGL.zig

@@ -137,7 +137,6 @@ const GPUCellMode = enum(u8) {
     cursor_rect = 3,
     cursor_rect_hollow = 4,
     cursor_bar = 5,
-    underline = 6,
     strikethrough = 8,
 
     // Non-exhaustive because masks change it
@@ -180,8 +179,6 @@ pub fn init(alloc: Allocator, options: renderer.Options) !OpenGL {
     const pbind = try program.use();
     defer pbind.unbind();
     try program.setUniform("cell_size", @Vector(2, f32){ metrics.cell_width, metrics.cell_height });
-    try program.setUniform("underline_position", metrics.underline_position);
-    try program.setUniform("underline_thickness", metrics.underline_thickness);
     try program.setUniform("strikethrough_position", metrics.strikethrough_position);
     try program.setUniform("strikethrough_thickness", metrics.strikethrough_thickness);
 
@@ -501,12 +498,6 @@ pub fn setFontSize(self: *OpenGL, size: font.face.DesiredSize) !void {
     if (std.meta.eql(self.cell_size, new_cell_size)) return;
     self.cell_size = new_cell_size;
 
-    // Set the cell size of the box font
-    if (self.font_group.group.sprite) |*sprite| {
-        sprite.width = @floatToInt(u32, self.cell_size.width);
-        sprite.height = @floatToInt(u32, self.cell_size.height);
-    }
-
     // Notify the window that the cell size changed.
     _ = self.window_mailbox.push(.{
         .cell_size = new_cell_size,
@@ -530,12 +521,18 @@ fn resetFontMetrics(
     };
     log.debug("cell dimensions={}", .{metrics});
 
+    // Set details for our sprite font
+    font_group.group.sprite = font.sprite.Face{
+        .width = @floatToInt(u32, metrics.cell_width),
+        .height = @floatToInt(u32, metrics.cell_height),
+        .thickness = 2,
+        .underline_position = @floatToInt(u32, metrics.underline_position),
+    };
+
     // Set our uniforms that rely on metrics
     const pbind = try program.use();
     defer pbind.unbind();
     try program.setUniform("cell_size", @Vector(2, f32){ metrics.cell_width, metrics.cell_height });
-    try program.setUniform("underline_position", metrics.underline_position);
-    try program.setUniform("underline_thickness", metrics.underline_thickness);
     try program.setUniform("strikethrough_position", metrics.strikethrough_position);
     try program.setUniform("strikethrough_thickness", metrics.strikethrough_thickness);
 
@@ -928,7 +925,7 @@ pub fn updateCell(
         var i: usize = 0;
         if (colors.bg != null) i += 1;
         if (!cell.empty()) i += 1;
-        if (cell.attrs.underline) i += 1;
+        if (cell.attrs.underline != .none) i += 1;
         if (cell.attrs.strikethrough) i += 1;
         break :needed i;
     };
@@ -1002,18 +999,33 @@ pub fn updateCell(
         });
     }
 
-    if (cell.attrs.underline) {
+    if (cell.attrs.underline != .none) {
+        const sprite: font.Sprite = switch (cell.attrs.underline) {
+            .none => unreachable,
+            .single => .underline,
+            .double => .underline_double,
+            .dotted => .underline_dotted,
+            .dashed => .underline_dashed,
+            .curly => .underline_curly,
+        };
+
+        const underline_glyph = try self.font_group.renderGlyph(
+            self.alloc,
+            font.sprite_index,
+            @enumToInt(sprite),
+            null,
+        );
         self.cells.appendAssumeCapacity(.{
-            .mode = .underline,
+            .mode = .fg,
             .grid_col = @intCast(u16, x),
             .grid_row = @intCast(u16, y),
             .grid_width = cell.widthLegacy(),
-            .glyph_x = 0,
-            .glyph_y = 0,
-            .glyph_width = 0,
-            .glyph_height = 0,
-            .glyph_offset_x = 0,
-            .glyph_offset_y = 0,
+            .glyph_x = underline_glyph.atlas_x,
+            .glyph_y = underline_glyph.atlas_y,
+            .glyph_width = underline_glyph.width,
+            .glyph_height = underline_glyph.height,
+            .glyph_offset_x = underline_glyph.offset_x,
+            .glyph_offset_y = underline_glyph.offset_y,
             .fg_r = colors.fg.r,
             .fg_g = colors.fg.g,
             .fg_b = colors.fg.b,

src/renderer/shaders/cell.f.glsl

@@ -30,7 +30,6 @@ const uint MODE_FG_COLOR = 7u;
 const uint MODE_CURSOR_RECT = 3u;
 const uint MODE_CURSOR_RECT_HOLLOW = 4u;
 const uint MODE_CURSOR_BAR = 5u;
-const uint MODE_UNDERLINE = 6u;
 const uint MODE_STRIKETHROUGH = 8u;
 
 void main() {
@@ -94,10 +93,6 @@ void main() {
         out_FragColor = color;
         break;
 
-    case MODE_UNDERLINE:
-        out_FragColor = color;
-        break;
-
     case MODE_STRIKETHROUGH:
         out_FragColor = color;
         break;

src/renderer/shaders/cell.metal

@@ -8,15 +8,12 @@ enum Mode : uint8_t {
     MODE_CURSOR_RECT = 3u,
     MODE_CURSOR_RECT_HOLLOW = 4u,
     MODE_CURSOR_BAR = 5u,
-    MODE_UNDERLINE = 6u,
     MODE_STRIKETHROUGH = 8u,
 };
 
 struct Uniforms {
   float4x4 projection_matrix;
   float2 cell_size;
-  float underline_position;
-  float underline_thickness;
   float strikethrough_position;
   float strikethrough_thickness;
 };
@@ -154,22 +151,6 @@ vertex VertexOut uber_vertex(
     break;
   }
 
-  case MODE_UNDERLINE: {
-    // Underline Y value is just our thickness
-    float2 underline_size = float2(cell_size_scaled.x, uniforms.underline_thickness);
-
-    // Position the underline where we are told to
-    float2 underline_offset = float2(cell_size_scaled.x, uniforms.underline_position);
-
-    // Go to the bottom of the cell, take away the size of the
-    // underline, and that is our position. We also float it slightly
-    // above the bottom.
-    cell_pos = cell_pos + underline_offset - (underline_size * position);
-
-    out.position = uniforms.projection_matrix * float4(cell_pos, 0.0f, 1.0);
-    break;
-  }
-
   case MODE_STRIKETHROUGH: {
     // Strikethrough Y value is just our thickness
     float2 strikethrough_size = float2(cell_size_scaled.x, uniforms.strikethrough_thickness);
@@ -259,9 +240,6 @@ fragment float4 uber_fragment(
   case MODE_CURSOR_BAR:
     return in.color;
 
-  case MODE_UNDERLINE:
-    return in.color;
-
   case MODE_STRIKETHROUGH:
     return in.color;
   }

src/renderer/shaders/cell.v.glsl

@@ -10,7 +10,6 @@ const uint MODE_FG_COLOR = 7u;
 const uint MODE_CURSOR_RECT = 3u;
 const uint MODE_CURSOR_RECT_HOLLOW = 4u;
 const uint MODE_CURSOR_BAR = 5u;
-const uint MODE_UNDERLINE = 6u;
 const uint MODE_STRIKETHROUGH = 8u;
 
 // The grid coordinates (x, y) where x < columns and y < rows
@@ -58,8 +57,6 @@ uniform sampler2D text;
 uniform sampler2D text_color;
 uniform vec2 cell_size;
 uniform mat4 projection;
-uniform float underline_position;
-uniform float underline_thickness;
 uniform float strikethrough_position;
 uniform float strikethrough_thickness;
 
@@ -200,22 +197,6 @@ void main() {
         color = bg_color_in / 255.0;
         break;
 
-    case MODE_UNDERLINE:
-        // Underline Y value is just our thickness
-        vec2 underline_size = vec2(cell_size_scaled.x, underline_thickness);
-
-        // Position the underline where we are told to
-        vec2 underline_offset = vec2(cell_size_scaled.x, underline_position) ;
-
-        // Go to the bottom of the cell, take away the size of the
-        // underline, and that is our position. We also float it slightly
-        // above the bottom.
-        cell_pos = cell_pos + underline_offset - (underline_size * position);
-
-        gl_Position = projection * vec4(cell_pos, cell_z, 1.0);
-        color = fg_color_in / 255.0;
-        break;
-
     case MODE_STRIKETHROUGH:
         // Strikethrough Y value is just our thickness
         vec2 strikethrough_size = vec2(cell_size_scaled.x, strikethrough_thickness);

src/terminal/Parser.zig

@@ -79,6 +79,10 @@ pub const Action = union(enum) {
         intermediates: []u8,
         params: []u16,
         final: u8,
+        sep: Sep,
+
+        /// The separator used for CSI params.
+        pub const Sep = enum { semicolon, colon };
 
         // Implement formatter for logging
         pub fn format(
@@ -392,6 +396,11 @@ fn doAction(self: *Parser, action: TransitionAction, c: u8) ?Action {
                     .intermediates = self.intermediates[0..self.intermediates_idx],
                     .params = self.params[0..self.params_idx],
                     .final = c,
+                    .sep = switch (self.params_sep) {
+                        .none, .semicolon => .semicolon,
+                        .colon => .colon,
+                        .mixed => unreachable,
+                    },
                 },
             };
         },

src/terminal/Screen.zig

@@ -56,6 +56,7 @@ const Allocator = std.mem.Allocator;
 
 const utf8proc = @import("utf8proc");
 const trace = @import("tracy").trace;
+const sgr = @import("sgr.zig");
 const color = @import("color.zig");
 const point = @import("point.zig");
 const CircBuf = @import("circ_buf.zig").CircBuf;
@@ -167,10 +168,10 @@ pub const Cell = struct {
         bold: bool = false,
         italic: bool = false,
         faint: bool = false,
-        underline: bool = false,
         blink: bool = false,
         inverse: bool = false,
         strikethrough: bool = false,
+        underline: sgr.Attribute.Underline = .none,
 
         /// True if this is a wide character. This char takes up
         /// two cells. The following cell ALWAYS is a space.
@@ -241,7 +242,7 @@ pub const Cell = struct {
     }
 
     test {
-        //log.warn("CELL={} {}", .{ @sizeOf(Cell), @alignOf(Cell) });
+        //log.warn("CELL={} bits={} {}", .{ @sizeOf(Cell), @bitSizeOf(Cell), @alignOf(Cell) });
         try std.testing.expectEqual(12, @sizeOf(Cell));
     }
 };

src/terminal/Terminal.zig

@@ -379,12 +379,12 @@ pub fn setAttribute(self: *Terminal, attr: sgr.Attribute) !void {
             self.screen.cursor.pen.attrs.faint = true;
         },
 
-        .underline => {
-            self.screen.cursor.pen.attrs.underline = true;
+        .underline => |v| {
+            self.screen.cursor.pen.attrs.underline = v;
         },
 
         .reset_underline => {
-            self.screen.cursor.pen.attrs.underline = false;
+            self.screen.cursor.pen.attrs.underline = .none;
         },
 
         .blink => {

src/terminal/sgr.zig

@@ -31,7 +31,7 @@ pub const Attribute = union(enum) {
     faint: void,
 
     /// Underline the text
-    underline: void,
+    underline: Underline,
     reset_underline: void,
 
     /// Blink the text
@@ -75,6 +75,15 @@ pub const Attribute = union(enum) {
         g: u8,
         b: u8,
     };
+
+    pub const Underline = enum(u3) {
+        none = 0,
+        single = 1,
+        double = 2,
+        curly = 3,
+        dotted = 4,
+        dashed = 5,
+    };
 };
 
 /// Parser parses the attributes from a list of SGR parameters.
@@ -82,6 +91,9 @@ pub const Parser = struct {
     params: []const u16,
     idx: usize = 0,
 
+    /// True if the separator is a colon
+    colon: bool = false,
+
     /// Next returns the next attribute or null if there are no more attributes.
     pub fn next(self: *Parser) ?Attribute {
         if (self.idx > self.params.len) return null;
@@ -107,7 +119,41 @@ pub const Parser = struct {
 
             3 => return Attribute{ .italic = {} },
 
-            4 => return Attribute{ .underline = {} },
+            4 => blk: {
+                if (self.colon) {
+                    switch (slice.len) {
+                        // 0 is unreachable because we're here and we read
+                        // an element to get here.
+                        0 => unreachable,
+
+                        // 1 is unreachable because we can't have a colon
+                        // separator if there are no separators.
+                        1 => unreachable,
+
+                        // 2 means we have a specific underline style.
+                        2 => {
+                            self.idx += 1;
+                            switch (slice[1]) {
+                                0 => return Attribute{ .reset_underline = {} },
+                                1 => return Attribute{ .underline = .single },
+                                2 => return Attribute{ .underline = .double },
+                                3 => return Attribute{ .underline = .curly },
+                                4 => return Attribute{ .underline = .dotted },
+                                5 => return Attribute{ .underline = .dashed },
+
+                                // For unknown underline styles, just render
+                                // a single underline.
+                                else => return Attribute{ .underline = .single },
+                            }
+                        },
+
+                        // Colon-separated must only be 2.
+                        else => break :blk,
+                    }
+                }
+
+                return Attribute{ .underline = .single };
+            },
 
             5 => return Attribute{ .blink = {} },
 
@@ -206,6 +252,11 @@ fn testParse(params: []const u16) Attribute {
     return p.next().?;
 }
 
+fn testParseColon(params: []const u16) Attribute {
+    var p: Parser = .{ .params = params, .colon = true };
+    return p.next().?;
+}
+
 test "sgr: Parser" {
     try testing.expect(testParse(&[_]u16{}) == .unset);
     try testing.expect(testParse(&[_]u16{0}) == .unset);
@@ -275,6 +326,37 @@ test "sgr: underline" {
     }
 }
 
+test "sgr: underline styles" {
+    {
+        const v = testParseColon(&[_]u16{ 4, 2 });
+        try testing.expect(v == .underline);
+        try testing.expect(v.underline == .double);
+    }
+
+    {
+        const v = testParseColon(&[_]u16{ 4, 0 });
+        try testing.expect(v == .reset_underline);
+    }
+
+    {
+        const v = testParseColon(&[_]u16{ 4, 1 });
+        try testing.expect(v == .underline);
+        try testing.expect(v.underline == .single);
+    }
+
+    {
+        const v = testParseColon(&[_]u16{ 4, 4 });
+        try testing.expect(v == .underline);
+        try testing.expect(v.underline == .dotted);
+    }
+
+    {
+        const v = testParseColon(&[_]u16{ 4, 5 });
+        try testing.expect(v == .underline);
+        try testing.expect(v.underline == .dashed);
+    }
+}
+
 test "sgr: blink" {
     {
         const v = testParse(&[_]u16{5});

src/terminal/stream.zig

@@ -383,7 +383,7 @@ pub fn Stream(comptime Handler: type) type {
 
                 // SGR - Select Graphic Rendition
                 'm' => if (@hasDecl(T, "setAttribute")) {
-                    var p: sgr.Parser = .{ .params = action.params };
+                    var p: sgr.Parser = .{ .params = action.params, .colon = action.sep == .colon };
                     while (p.next()) |attr| try self.handler.setAttribute(attr);
                 } else log.warn("unimplemented CSI callback: {}", .{action}),