style: unit conversion

Implemented the golang.org/x/exp/shiny/unit.Converter interface on
style.Style.

1 files changed, 62 insertions, 0 deletions

diff --git a/style/options.go b/style/options.go
new file mode 100644
index 0000000..c1514c0
--- /dev/null
+++ b/style/options.go
@@ -0,0 +1,62 @@
+package style
+
+import (
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/gofont/goregular"
+	"golang.org/x/image/font/opentype"
+)
+
+var defaultOptions = options{
+	font: goregular.TTF,
+	FaceOptions: opentype.FaceOptions{
+		DefaultFontSize,
+		DefaultDpi,
+		DefaultHinting,
+	},
+}
+
+// Option is a functional option to Style constructor, New.
+type Option func(*options)
+
+type options struct {
+	font []byte
+	opentype.FaceOptions
+}
+
+func parseOpts(opts ...Option) options {
+	o := defaultOptions
+	for i := range opts {
+		opts[i](&o)
+	}
+	return o
+}
+
+// Font option sets the font source to use. It takes TTF or OTF data
+// (see golang.org/x/image/font/opentype.Parse).
+func Font(src []byte) Option {
+	return func(o *options) {
+		o.font = src
+	}
+}
+
+// FontSize option sets the font size in points (1/72").
+func FontSize(size float64) Option {
+	return func(o *options) {
+		o.FaceOptions.Size = size
+	}
+}
+
+// Dpi option sets the dots per inch resolution of the display.
+func Dpi(dpi float64) Option {
+	return func(o *options) {
+		o.FaceOptions.DPI = dpi
+	}
+}
+
+// Hinting options selects how to quantize a vector font's glyph
+// nodes.
+func Hinting(h font.Hinting) Option {
+	return func(o *options) {
+		o.FaceOptions.Hinting = h
+	}
+}