diff --git a/src/font/sprite/underline.zig b/src/font/sprite/underline.zig index c60fd71b7..af0dd739a 100644 --- a/src/font/sprite/underline.zig +++ b/src/font/sprite/underline.zig @@ -27,189 +27,166 @@ pub fn renderGlyph( 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); + // _ = height; - // Perform the actual drawing - (Draw{ - .width = width, - .height = height, - .pos = line_pos, - .thickness = line_thickness, - }).draw(&canvas, sprite); + // Draw the appropriate sprite + var canvas: font.sprite.Canvas, const offset_y: i32 = switch (sprite) { + .underline => try drawSingle(alloc, width, line_thickness), + .underline_double => try drawDouble(alloc, width, line_thickness), + .underline_dotted => try drawDotted(alloc, width, line_thickness), + .underline_dashed => try drawDashed(alloc, width, line_thickness), + .underline_curly => try drawCurly(alloc, width, line_thickness), + .strikethrough => try drawSingle(alloc, width, line_thickness), + else => unreachable, + }; + defer canvas.deinit(alloc); // 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 = @as(i32, @intCast(height)); - return font.Glyph{ .width = width, - .height = height, + .height = @intCast(region.height), .offset_x = 0, - .offset_y = offset_y, + .offset_y = @as(i32, @intCast(height + region.height)) - @as(i32, @intCast(line_pos)) + offset_y + 1, .atlas_x = region.x, .atlas_y = region.y, .advance_x = @floatFromInt(width), }; } -/// Stores drawing state. -const Draw = struct { - width: u32, - height: u32, - pos: u32, - thickness: u32, +/// Draw a single underline. +fn drawSingle(alloc: Allocator, width: u32, thickness: u32) !struct { font.sprite.Canvas, i32 } { + const height: u32 = thickness; + var canvas = try font.sprite.Canvas.init(alloc, width, height); - /// 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), - .strikethrough => self.drawSingle(canvas), - else => unreachable, - } - } + canvas.rect(.{ + .x = 0, + .y = 0, + .width = width, + .height = thickness, + }, .on); - /// Draw a single underline. - fn drawSingle(self: Draw, canvas: *font.sprite.Canvas) void { - // Ensure we never overflow out of bounds on the canvas - const y_max = self.height -| 1; - const bottom = @min(self.pos + self.thickness, y_max); - const y = bottom -| self.thickness; - const max_height = self.height - y; + const offset_y: i32 = 0; + return .{ canvas, offset_y }; +} + +/// Draw a double underline. +fn drawDouble(alloc: Allocator, width: u32, thickness: u32) !struct { font.sprite.Canvas, i32 } { + const height: u32 = thickness * 3; + var canvas = try font.sprite.Canvas.init(alloc, width, height); + + canvas.rect(.{ + .x = 0, + .y = 0, + .width = width, + .height = thickness, + }, .on); + + canvas.rect(.{ + .x = 0, + .y = @intCast(thickness * 2), + .width = width, + .height = thickness, + }, .on); + + const offset_y: i32 = -@as(i32, @intCast(thickness)); + + return .{ canvas, offset_y }; +} + +/// Draw a dotted underline. +fn drawDotted(alloc: Allocator, width: u32, thickness: u32) !struct { font.sprite.Canvas, i32 } { + const height: u32 = thickness; + var canvas = try font.sprite.Canvas.init(alloc, width, height); + + const dot_width = @max(thickness, 3); + const dot_count = width / dot_width; + var i: u32 = 0; + while (i < dot_count) : (i += 2) { + // Ensure we never go out of bounds for the rect + const x = @min(i * dot_width, width - 1); + const rect_width = @min(width - x, dot_width); canvas.rect(.{ - .x = 0, - .y = @intCast(y), - .width = self.width, - .height = @min(self.thickness, max_height), + .x = @intCast(i * dot_width), + .y = 0, + .width = rect_width, + .height = thickness, }, .on); } - /// Draw a double underline. - fn drawDouble(self: Draw, canvas: *font.sprite.Canvas) void { - // The maximum y value has to have space for the bottom underline. - // If we underflow (saturated) to 0, then we don't draw. This should - // never happen but we don't want to draw something undefined. - const y_max = self.height -| 1 -| self.thickness; - if (y_max == 0) return; + const offset_y: i32 = 0; - const space = self.thickness * 2; - const bottom = @min(self.pos + space, y_max); - const top = bottom - space; + return .{ canvas, offset_y }; +} +/// Draw a dashed underline. +fn drawDashed(alloc: Allocator, width: u32, thickness: u32) !struct { font.sprite.Canvas, i32 } { + const height: u32 = thickness; + var canvas = try font.sprite.Canvas.init(alloc, width, height); + + const dash_width = width / 3 + 1; + const dash_count = (width / dash_width) + 1; + var i: u32 = 0; + while (i < dash_count) : (i += 2) { + // Ensure we never go out of bounds for the rect + const x = @min(i * dash_width, width - 1); + const rect_width = @min(width - x, dash_width); canvas.rect(.{ - .x = 0, - .y = @intCast(top), - .width = self.width, - .height = self.thickness, - }, .on); - - canvas.rect(.{ - .x = 0, - .y = @intCast(bottom), - .width = self.width, - .height = self.thickness, + .x = @intCast(x), + .y = 0, + .width = rect_width, + .height = thickness, }, .on); } - /// Draw a dotted underline. - fn drawDotted(self: Draw, canvas: *font.sprite.Canvas) void { - const y_max = self.height -| 1 -| self.thickness; - if (y_max == 0) return; - const y = @min(self.pos, y_max); - const dot_width = @max(self.thickness, 3); - const dot_count = self.width / dot_width; - var i: u32 = 0; - while (i < dot_count) : (i += 2) { - // Ensure we never go out of bounds for the rect - const x = @min(i * dot_width, self.width - 1); - const width = @min(self.width - x, dot_width); - canvas.rect(.{ - .x = @intCast(i * dot_width), - .y = @intCast(y), - .width = width, - .height = self.thickness, - }, .on); + const offset_y: i32 = 0; + + return .{ canvas, offset_y }; +} + +/// 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(alloc: Allocator, width: u32, thickness: u32) !struct { font.sprite.Canvas, i32 } { + const height: u32 = thickness * 4; + var canvas = try font.sprite.Canvas.init(alloc, width, height); + + // Calculate the wave period for a single character + // `2 * pi...` = 1 peak per character + // `4 * pi...` = 2 peaks per character + const wave_period = 2 * std.math.pi / @as(f64, @floatFromInt(width - 1)); + + // The full amplitude of the wave can be from the bottom to the + // underline position. We also calculate our mid y point of the wave + const half_amplitude: f64 = @as(f64, @floatFromInt(thickness)); + const y_mid: f64 = half_amplitude + 1; + + // follow Xiaolin Wu's antialias algorithm to draw the curve + var x: u32 = 0; + while (x < width) : (x += 1) { + const cosx: f64 = @cos(@as(f64, @floatFromInt(x)) * wave_period); + const y: f64 = y_mid + half_amplitude * cosx; + const y_upper: u32 = @intFromFloat(@floor(y)); + const y_lower: u32 = y_upper + thickness + (thickness >> 1); + const alpha: u8 = @intFromFloat(255 * @abs(y - @floor(y))); + + // upper and lower bounds + canvas.pixel(x, @min(y_upper, height), @enumFromInt(255 - alpha)); + canvas.pixel(x, @min(y_lower, height), @enumFromInt(alpha)); + + // fill between upper and lower bound + var y_fill: u32 = y_upper + 1; + while (y_fill < y_lower) : (y_fill += 1) { + canvas.pixel(x, @min(y_fill, height), .on); } } - /// Draw a dashed underline. - fn drawDashed(self: Draw, canvas: *font.sprite.Canvas) void { - const y_max = self.height -| 1 -| self.thickness; - if (y_max == 0) return; - const y = @min(self.pos, y_max); - 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) { - // Ensure we never go out of bounds for the rect - const x = @min(i * dash_width, self.width - 1); - const width = @min(self.width - x, dash_width); - canvas.rect(.{ - .x = @intCast(x), - .y = @intCast(y), - .width = width, - .height = self.thickness, - }, .on); - } - } + const offset_y: i32 = -@as(i32, @intCast(thickness * 2)); - /// 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; - - // Calculate the wave period for a single character - // `2 * pi...` = 1 peak per character - // `4 * pi...` = 2 peaks per character - const wave_period = 2 * std.math.pi / @as(f64, @floatFromInt(self.width - 1)); - - // Some fonts put the underline too close to the bottom of the - // cell height and this doesn't allow us to make a high enough - // wave. This constant is arbitrary, change it for aesthetics. - const pos: u32 = pos: { - const MIN_AMPLITUDE: u32 = @max(self.height / 9, 2); - break :pos y_max - (MIN_AMPLITUDE * 2); - }; - - // The full amplitude of the wave can be from the bottom to the - // underline position. We also calculate our mid y point of the wave - const double_amplitude: f64 = @floatFromInt(y_max - pos); - const half_amplitude: f64 = @max(1, double_amplitude / 4); - const y_mid: u32 = pos + @as(u32, @intFromFloat(2 * half_amplitude)); - - // follow Xiaolin Wu's antialias algorithm to draw the curve - var x: u32 = 0; - while (x < self.width) : (x += 1) { - const y: f64 = @as(f64, @floatFromInt(y_mid)) + (half_amplitude * @cos(@as(f64, @floatFromInt(x)) * wave_period)); - const y_upper: u32 = @intFromFloat(@floor(y)); - const y_lower: u32 = y_upper + self.thickness; - const alpha: u8 = @intFromFloat(255 * @abs(y - @floor(y))); - - // upper and lower bounds - canvas.pixel(x, @min(y_upper, y_max), @enumFromInt(255 - alpha)); - canvas.pixel(x, @min(y_lower, y_max), @enumFromInt(alpha)); - - // fill between upper and lower bound - var y_fill: u32 = y_upper + 1; - while (y_fill < y_lower) : (y_fill += 1) { - canvas.pixel(x, @min(y_fill, y_max), .on); - } - } - } -}; + return .{ canvas, offset_y }; +} test "single" { const testing = std.testing;