Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

drawing/text.go

@@ -0,0 +1,67 @@
+package drawing
+
+import (
+	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/math/fixed"
+)
+
+// DrawContour draws the given closed contour at the given sub-pixel offset.
+func DrawContour(path PathBuilder, ps []truetype.Point, dx, dy float64) {
+	if len(ps) == 0 {
+		return
+	}
+	startX, startY := pointToF64Point(ps[0])
+	path.MoveTo(startX+dx, startY+dy)
+	q0X, q0Y, on0 := startX, startY, true
+	for _, p := range ps[1:] {
+		qX, qY := pointToF64Point(p)
+		on := p.Flags&0x01 != 0
+		if on {
+			if on0 {
+				path.LineTo(qX+dx, qY+dy)
+			} else {
+				path.QuadCurveTo(q0X+dx, q0Y+dy, qX+dx, qY+dy)
+			}
+		} else if !on0 {
+			midX := (q0X + qX) / 2
+			midY := (q0Y + qY) / 2
+			path.QuadCurveTo(q0X+dx, q0Y+dy, midX+dx, midY+dy)
+		}
+		q0X, q0Y, on0 = qX, qY, on
+	}
+	// Close the curve.
+	if on0 {
+		path.LineTo(startX+dx, startY+dy)
+	} else {
+		path.QuadCurveTo(q0X+dx, q0Y+dy, startX+dx, startY+dy)
+	}
+}
+
+// FontExtents contains font metric information.
+type FontExtents struct {
+	// Ascent is the distance that the text
+	// extends above the baseline.
+	Ascent float64
+
+	// Descent is the distance that the text
+	// extends below the baseline.  The descent
+	// is given as a negative value.
+	Descent float64
+
+	// Height is the distance from the lowest
+	// descending point to the highest ascending
+	// point.
+	Height float64
+}
+
+// Extents returns the FontExtents for a font.
+// TODO needs to read this https://developer.apple.com/fonts/TrueType-Reference-Manual/RM02/Chap2.html#intro
+func Extents(font *truetype.Font, size float64) FontExtents {
+	bounds := font.Bounds(fixed.Int26_6(font.FUnitsPerEm()))
+	scale := size / float64(font.FUnitsPerEm())
+	return FontExtents{
+		Ascent:  float64(bounds.Max.Y) * scale,
+		Descent: float64(bounds.Min.Y) * scale,
+		Height:  float64(bounds.Max.Y-bounds.Min.Y) * scale,
+	}
+}