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font: coretext calculate cell metrics

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This commit is contained in:
Mitchell Hashimoto
2022-10-09 10:57:19 -07:00
parent 150b0a4d51
commit 1b7bc052d4
5 changed files with 177 additions and 11 deletions
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56
src/font/face/coretext.zig
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@@ -122,7 +122,10 @@ pub const Face = struct {
// to tell us after laying out some text. This is inspired by Kitty's
// approach. Previously we were using descent/ascent math and it wasn't
// quite the same with CoreText and I never figured out why.
const cell_height: f32 = cell_height: {
const layout_metrics: struct {
height: f32,
ascent: f32,
} = metrics: {
const unit = "AQWMH_gyl " ** 100;
// Setup our string we'll layout. We just stylize a string of
@@ -156,24 +159,55 @@ pub const Face = struct {
);
defer frame.release();
// Get the two points where the lines start in order to determine
// the line height.
// Use our text layout from earlier to measure the difference
// between the lines.
var points: [2]macos.graphics.Point = undefined;
frame.getLineOrigins(macos.foundation.Range.init(0, 1), points[0..]);
frame.getLineOrigins(macos.foundation.Range.init(1, 1), points[1..]);
break :cell_height @floatCast(f32, points[0].y - points[1].y);
const lines = frame.getLines();
const line = lines.getValueAtIndex(macos.text.Line, 0);
// NOTE(mitchellh): For some reason, CTLineGetBoundsWithOptions
// returns garbage and I can't figure out why... so we use the
// raw ascender.
var ascent: f64 = 0;
var descent: f64 = 0;
var leading: f64 = 0;
_ = line.getTypographicBounds(&ascent, &descent, &leading);
//std.log.warn("ascent={} descent={} leading={}", .{ ascent, descent, leading });
break :metrics .{
.height = @floatCast(f32, points[0].y - points[1].y),
.ascent = @floatCast(f32, ascent),
};
};
std.log.warn("width={}, height={}", .{ cell_width, cell_height });
// All of these metrics are based on our layout above.
const cell_height = layout_metrics.height;
const cell_baseline = layout_metrics.ascent;
const underline_position = @ceil(layout_metrics.ascent -
@floatCast(f32, ct_font.getUnderlinePosition()));
const underline_thickness = @ceil(@floatCast(f32, ct_font.getUnderlineThickness()));
const strikethrough_position = cell_baseline * 0.6;
const strikethrough_thickness = underline_thickness;
// std.log.warn("width={d}, height={d} baseline={d} underline_pos={d} underline_thickness={d}", .{
// cell_width,
// cell_height,
// cell_baseline,
// underline_position,
// underline_thickness,
// });
return font.face.Metrics{
.cell_width = cell_width,
.cell_height = cell_height,
.cell_baseline = 0,
.underline_position = 0,
.underline_thickness = 0,
.strikethrough_position = 0,
.strikethrough_thickness = 0,
.cell_baseline = cell_baseline,
.underline_position = underline_position,
.underline_thickness = underline_thickness,
.strikethrough_position = strikethrough_position,
.strikethrough_thickness = strikethrough_thickness,
};
}
};
@@ -188,7 +222,7 @@ test {
const ct_font = try macos.text.Font.createWithFontDescriptor(desc, 12);
defer ct_font.release();
var face = try Face.initFontCopy(ct_font, .{ .points = 18 });
var face = try Face.initFontCopy(ct_font, .{ .points = 12 });
defer face.deinit();
try testing.expectEqual(font.Presentation.text, face.presentation);