Polygon function and demonstration

3 files changed, 75 insertions, 1 deletions

diff --git a/doc.go b/doc.go
index 5399b02..d62a20d 100644
--- a/doc.go
+++ b/doc.go
@@ -66,7 +66,8 @@ FPDF product. Lawrence Kesteloot provided code to allow an image's extent to be
 determined prior to placement. Support for vertical alignment within a cell was
 provided by Stefan Schroeder. Ivan Daniluk generalized the font and image
 loading code to use the Reader interface while maintaining backward
-compatibility. Bruno Michel has provided valuable assistance with the code.
+compatibility. Anthony Starks provided code for the Polygon function. Bruno
+Michel has provided valuable assistance with the code.
 
 The FPDF website is http://www.fpdf.org/.
 
diff --git a/fpdf.go b/fpdf.go
index 4c6fa81..4a43fe4 100644
--- a/fpdf.go
+++ b/fpdf.go
@@ -798,6 +798,31 @@ func (f *Fpdf) Ellipse(x, y, rx, ry, degRotate float64, styleStr string) {
 	f.Arc(x, y, rx, ry, degRotate, 0, 360, styleStr)
 }
 
+// Polygon draws a closed figure defined by a series of vertices specified by
+// points. The x and y fields of the points use the units established in New().
+// The last point in the slice will be implicitly joined to the first to close
+// the polygon.
+//
+// styleStr can be "F" for filled, "D" for outlined only, or "DF" or "FD" for
+// outlined and filled. An empty string will be replaced with "D". Drawing uses
+// the current draw color and line width centered on the ellipse's perimeter.
+// Filling uses the current fill color.
+//
+// See tutorial 25 for an example of this function.
+func (f *Fpdf) Polygon(points []PointType, styleStr string) {
+	if len(points) > 2 {
+		for j, pt := range points {
+			if j == 0 {
+				f.point(pt.X, pt.Y)
+			} else {
+				f.outf("%.5f %.5f l ", pt.X*f.k, (f.h-pt.Y)*f.k)
+			}
+		}
+		f.outf("%.5f %.5f l ", points[0].X*f.k, (f.h-points[0].Y)*f.k)
+		f.outf(fillDrawOp(styleStr))
+	}
+}
+
 // Outputs current point
 func (f *Fpdf) point(x, y float64) {
 	f.outf("%.2f %.2f m", x*f.k, (f.h-y)*f.k)
diff --git a/fpdf_test.go b/fpdf_test.go
index c727087..262e482 100644
--- a/fpdf_test.go
+++ b/fpdf_test.go
@@ -21,6 +21,7 @@ import (
 	"code.google.com/p/gofpdf"
 	"fmt"
 	"io/ioutil"
+	"math"
 	"os"
 	"path/filepath"
 	"strings"
@@ -1197,3 +1198,50 @@ func ExampleFpdf_tutorial24() {
 	// Output:
 	// Successfully generated pdf/tutorial24.pdf
 }
+
+// This example displays equilateral polygons in a demonstration of the Polygon
+// function.
+func ExampleFpdf_tutorial25() {
+	const rowCount = 5
+	const colCount = 4
+	const ptSize = 36
+	var x, y, radius, gap, advance float64
+	var rgVal int
+	var pts []gofpdf.PointType
+	vertices := func(count int) (res []gofpdf.PointType) {
+		var pt gofpdf.PointType
+		res = make([]gofpdf.PointType, 0, count)
+		mlt := 2.0 * math.Pi / float64(count)
+		for j := 0; j < count; j++ {
+			pt.Y, pt.X = math.Sincos(float64(j) * mlt)
+			res = append(res, gofpdf.PointType{x + radius*pt.X, y + radius*pt.Y})
+		}
+		return
+	}
+	pdf := gofpdf.New("P", "mm", "A4", cnFontDir) // A4 210.0 x 297.0
+	pdf.AddPage()
+	pdf.SetFont("Helvetica", "", ptSize)
+	pdf.SetDrawColor(0, 80, 180)
+	gap = 12.0
+	pdf.SetY(gap)
+	pdf.CellFormat(190.0, gap, "Equilateral polygons", "", 1, "C", false, 0, "")
+	radius = (210.0 - float64(colCount+1)*gap) / (2.0 * float64(colCount))
+	advance = gap + 2.0*radius
+	y = 2*gap + pdf.PointConvert(ptSize) + radius
+	rgVal = 230
+	for row := 0; row < rowCount; row++ {
+		pdf.SetFillColor(rgVal, rgVal, 0)
+		rgVal -= 12
+		x = gap + radius
+		for col := 0; col < colCount; col++ {
+			pts = vertices(row*colCount + col + 3)
+			// pdf.Circle(x, y, radius, "FD")
+			pdf.Polygon(pts, "FD")
+			x += advance
+		}
+		y += advance
+	}
+	pdf.OutputAndClose(docWriter(pdf, 25))
+	// Output:
+	// Successfully generated pdf/tutorial25.pdf
+}