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coretext: render glyph on its own bounding box, calculate bearings

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This commit is contained in:
Mitchell Hashimoto
2022-10-18 14:49:23 -07:00
parent 38e0c258d0
commit c00c8f52b5
1 changed files with 28 additions and 16 deletions
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44
src/font/face/coretext.zig
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@ -104,11 +104,8 @@ pub const Face = struct {
_ = self.font.getBoundingRectForGlyphs(.horizontal, &glyphs, &bounding);
const glyph_width = @floatToInt(u32, @ceil(bounding[0].size.width));
const glyph_height = @floatToInt(u32, @ceil(bounding[0].size.height));
_ = glyph_height;
const width = @floatToInt(u32, self.metrics.cell_width);
const height = @floatToInt(u32, self.metrics.cell_height);
// const width = glyph_width;
// const height = glyph_height;
const width = glyph_width;
const height = glyph_height;
// This bitmap is blank. I've seen it happen in a font, I don't know why.
// If it is empty, we just return a valid glyph struct that does nothing.
@ -122,8 +119,6 @@ pub const Face = struct {
.advance_x = 0,
};
//std.log.warn("bound={}", .{bounding[0]});
// Get the advance that we need for the glyph
var advances: [1]macos.graphics.Size = undefined;
_ = self.font.getAdvancesForGlyphs(.horizontal, &glyphs, &advances);
@ -157,24 +152,41 @@ pub const Face = struct {
ctx.setGrayStrokeColor(1, 1);
ctx.setTextDrawingMode(.fill_stroke);
ctx.setTextMatrix(macos.graphics.AffineTransform.identity());
ctx.setTextPosition(0, @intToFloat(f32, height) - self.metrics.cell_baseline);
//ctx.setTextPosition(0, 0);
ctx.setTextPosition(0, 0);
var pos = [_]macos.graphics.Point{.{ .x = 0, .y = 0 }};
// We want to render the glyphs at (0,0), but the glyphs themselves
// are offset by bearings, so we have to undo those bearings in order
// to get them to 0,0.
var pos = [_]macos.graphics.Point{.{
.x = -1 * bounding[0].origin.x,
.y = -1 * bounding[0].origin.y,
}};
self.font.drawGlyphs(&glyphs, &pos, ctx);
const region = try atlas.reserve(alloc, width, height);
atlas.set(region, buf);
const offset_y = offset_y: {
// Our Y coordinate in 3D is (0, 0) bottom left, +y is UP.
// We need to calculate our baseline from the bottom of a cell.
const baseline_from_bottom = self.metrics.cell_height - self.metrics.cell_baseline;
// Next we offset our baseline by the bearing in the font. We
// ADD here because CoreText y is UP.
const baseline_with_offset = baseline_from_bottom + bounding[0].origin.y;
// Finally, since we're rendering at (0, 0), the glyph will render
// by default below the line. We have to add height (glyph height)
// so that we shift the glyph UP to be on the line, then we add our
// baseline offset to move the glyph further UP to match the baseline.
break :offset_y @intCast(i32, height) + @floatToInt(i32, @ceil(baseline_with_offset));
};
return font.Glyph{
.width = width,
.height = height,
.offset_x = 0,
// Offset is full cell height because for CoreText we render
// an entire cell.
.offset_y = @floatToInt(i32, self.metrics.cell_height),
.offset_x = @floatToInt(i32, @ceil(bounding[0].origin.x)),
.offset_y = offset_y,
.atlas_x = region.x,
.atlas_y = region.y,
.advance_x = @floatCast(f32, advances[0].width),