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Merge pull request #774 from mitchellh/update-undercurl

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feat: update undercurl thickness and wave height
This commit is contained in:
Mitchell Hashimoto
2023-11-01 17:19:54 -07:00
committed by GitHub
parent 0df9c0e2a3 a81c7b7bb2
commit cc6985d62d
1 changed files with 10 additions and 12 deletions
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22
src/font/sprite/underline.zig
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@@ -166,33 +166,31 @@ const Draw = struct {
// This is the lowest that the curl can go. // This is the lowest that the curl can go.
const y_max = self.height - 1; const y_max = self.height - 1;
// Determines the density of the waves. // Calculate the wave period for a single character
// `2 * pi...` = 1 peak per character // `2 * pi...` = 1 peak per character
// `4 * pi...` = 2 peaks per character // `4 * pi...` = 2 peaks per character
const x_factor = 2 * std.math.pi / @as(f64, @floatFromInt(self.width - 1)); 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 // 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 // cell height and this doesn't allow us to make a high enough
// wave. This constant is arbitrary, change it for aesthetics. // wave. This constant is arbitrary, change it for aesthetics.
const pos: u32 = pos: { const pos: u32 = pos: {
const MIN_HEIGHT = 5; const MIN_AMPLITUDE: u32 = @max(self.height / 9, 2);
const clamped_pos = @min(y_max, self.pos); break :pos y_max - (MIN_AMPLITUDE * 2);
const height = y_max - clamped_pos;
break :pos if (height < MIN_HEIGHT) clamped_pos -| MIN_HEIGHT else clamped_pos;
}; };
// The full height of the wave can be from the bottom to the // The full aplitude of the wave can be from the bottom to the
// underline position. We also calculate our mid y point of the wave // underline position. We also calculate our mid y point of the wave
const wave_height: f64 = @floatFromInt(y_max - pos); const double_amplitude: f64 = @floatFromInt(y_max - pos);
const half_height: f64 = @max(1, wave_height / 4); const half_amplitude: f64 = @max(1, double_amplitude / 4);
const y_mid: u32 = pos + @as(u32, @intFromFloat(2 * half_height)); const y_mid: u32 = pos + @as(u32, @intFromFloat(2 * half_amplitude));
// follow Xiaolin Wu's antialias algorithm to draw the curve // follow Xiaolin Wu's antialias algorithm to draw the curve
var x: u32 = 0; var x: u32 = 0;
while (x < self.width) : (x += 1) { while (x < self.width) : (x += 1) {
const y: f64 = @as(f64, @floatFromInt(y_mid)) + (half_height * @cos(@as(f64, @floatFromInt(x)) * x_factor)); 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_upper: u32 = @intFromFloat(@floor(y));
const y_lower: u32 = y_upper - 1 + self.thickness; const y_lower: u32 = y_upper + self.thickness;
const alpha: u8 = @intFromFloat(255 * @abs(y - @floor(y))); const alpha: u8 = @intFromFloat(255 * @abs(y - @floor(y)));
// upper and lower bounds // upper and lower bounds