font,vg: migrate vg.Length to font.Length

Author: sbinet

font/doc.go

@@ -0,0 +1,6 @@
+// Copyright ©2021 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package font provides types to describe and select text font faces.
+package font // import "gonum.org/v1/plot/font"

font/len.go

@@ -0,0 +1,68 @@
+// Copyright ©2021 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package font
+
+import (
+	"strconv"
+	"strings"
+)
+
+// Length is a unit-independent representation of length.
+// Internally, the length is stored in postscript points.
+type Length float64
+
+// Dots returns the length in dots for the given resolution.
+func (l Length) Dots(dpi float64) float64 {
+	return float64(l) / Inch.Points() * dpi
+}
+
+// Points returns the length in postscript points.
+func (l Length) Points() float64 {
+	return float64(l)
+}
+
+// Common lengths.
+const (
+	Inch       Length = 72
+	Centimeter        = Inch / 2.54
+	Millimeter        = Centimeter / 10
+)
+
+// Points returns a length for the given number of points.
+func Points(pt float64) Length {
+	return Length(pt)
+}
+
+// ParseLength parses a Length string.
+// A Length string is a possible signed floating number with a unit.
+// e.g. "42cm" "2.4in" "66pt"
+// If no unit was given, ParseLength assumes it was (postscript) points.
+// Currently valid units are:
+//   mm (millimeter)
+//   cm (centimeter)
+//   in (inch)
+//   pt (point)
+func ParseLength(value string) (Length, error) {
+	var unit Length = 1
+	switch {
+	case strings.HasSuffix(value, "in"):
+		value = value[:len(value)-len("in")]
+		unit = Inch
+	case strings.HasSuffix(value, "cm"):
+		value = value[:len(value)-len("cm")]
+		unit = Centimeter
+	case strings.HasSuffix(value, "mm"):
+		value = value[:len(value)-len("mm")]
+		unit = Millimeter
+	case strings.HasSuffix(value, "pt"):
+		value = value[:len(value)-len("pt")]
+		unit = 1
+	}
+	v, err := strconv.ParseFloat(value, 64)
+	if err != nil {
+		return 0, err
+	}
+	return Length(v) * unit, nil
+}

vg/len.go

@@ -4,37 +4,24 @@
 
 package vg
 
-import (
-	"strconv"
-	"strings"
-)
+import "gonum.org/v1/plot/font"
 
 // A Length is a unit-independent representation of length.
 // Internally, the length is stored in postscript points.
-type Length float64
+type Length = font.Length
 
 // Points returns a length for the given number of points.
 func Points(pt float64) Length {
-	return Length(pt)
+	return font.Points(pt)
 }
 
 // Common lengths.
 const (
-	Inch       Length = 72
-	Centimeter        = Inch / 2.54
-	Millimeter        = Centimeter / 10
+	Inch       = font.Inch
+	Centimeter = font.Centimeter
+	Millimeter = font.Millimeter
 )
 
-// Dots returns the length in dots for the given resolution.
-func (l Length) Dots(dpi float64) float64 {
-	return float64(l) / Inch.Points() * dpi
-}
-
-// Points returns the length in postscript points.
-func (l Length) Points() float64 {
-	return float64(l)
-}
-
 // ParseLength parses a Length string.
 // A Length string is a possible signed floating number with a unit.
 // e.g. "42cm" "2.4in" "66pt"
@@ -45,24 +32,5 @@ func (l Length) Points() float64 {
 //   in (inch)
 //   pt (point)
 func ParseLength(value string) (Length, error) {
-	var unit Length = 1
-	switch {
-	case strings.HasSuffix(value, "in"):
-		value = value[:len(value)-len("in")]
-		unit = Inch
-	case strings.HasSuffix(value, "cm"):
-		value = value[:len(value)-len("cm")]
-		unit = Centimeter
-	case strings.HasSuffix(value, "mm"):
-		value = value[:len(value)-len("mm")]
-		unit = Millimeter
-	case strings.HasSuffix(value, "pt"):
-		value = value[:len(value)-len("pt")]
-		unit = 1
-	}
-	v, err := strconv.ParseFloat(value, 64)
-	if err != nil {
-		return 0, err
-	}
-	return Length(v) * unit, nil
+	return font.ParseLength(value)
 }