Set error condition if out-of-range Unicode rune is encountered in GetStringWidth

2 files changed, 30 insertions, 3 deletions

diff --git a/fpdf.go b/fpdf.go
index 7b286a2..a7fb350 100644
--- a/fpdf.go
+++ b/fpdf.go
@@ -658,9 +658,20 @@ func (f *Fpdf) SetTextColor(r, g, b int) {
 
 // Returns the length of a string in user units. A font must be selected.
 func (f *Fpdf) GetStringWidth(s string) float64 {
+	if f.err != nil {
+		return 0
+	}
 	w := 0
+	count := rune(len(f.currentFont.Cw))
 	for _, ch := range s {
-		w += f.currentFont.Cw[ch]
+		if ch < count {
+			w += f.currentFont.Cw[ch]
+		} else {
+			if f.err == nil {
+				f.err = fmt.Errorf("Unicode strings not supported")
+			}
+			return 0
+		}
 	}
 	return float64(w) * f.fontSize / 1000
 }
diff --git a/ttfparser_test.go b/ttfparser_test.go
index 00f4030..9bb3d71 100644
--- a/ttfparser_test.go
+++ b/ttfparser_test.go
@@ -19,8 +19,7 @@ package gofpdf_test
 import (
 	"code.google.com/p/gofpdf"
 	"fmt"
-
-//	"testing"
+	// "testing"
 )
 
 func ExampleTtfParse() {
@@ -67,3 +66,20 @@ func ExampleTtfParse() {
 // 		}
 // 	}
 // }
+
+func ExampleFpdf_GetStringWidth() {
+	pdf := gofpdf.New("", "", "", FONT_DIR)
+	pdf.SetFont("Helvetica", "", 12)
+	pdf.AddPage()
+	for _, s := range []string{"Hello", "世界"} {
+		fmt.Printf("Width of \"%s\" is %.2f\n", s, pdf.GetStringWidth(s))
+		if pdf.Err() {
+			fmt.Println(pdf.Error())
+		}
+	}
+	pdf.Close()
+	// Output:
+	// Width of "Hello" is 9.64
+	// Width of "世界" is 0.00
+	// Unicode strings not supported
+}