Added some comments to new encoding/decoding methods

5 files changed, 33 insertions, 89 deletions

diff --git a/README.md b/README.md
index 953857b..2a8d606 100644
--- a/README.md
+++ b/README.md
@@ -221,7 +221,9 @@ account when calculating image size. Paulo Coutinho provided support for static
 embedded fonts. Dan Meyers added support for embedded JavaScript. David Fish
 added a generic alias-replacement function to enable, among other things, table
 of contents functionality. Andy Bakun identified and corrected a problem in
-which the internal catalogs were not sorted stably.
+which the internal catalogs were not sorted stably. d1ngd0 added encoding and
+decoding functionality for templates, including images that are embedded in
+templates; this allows templates to be stored independently of gofpdf.
 
 ## Roadmap
 
diff --git a/def.go b/def.go
index 3c5fa9d..605cdbc 100644
--- a/def.go
+++ b/def.go
@@ -158,7 +158,9 @@ func (p PointType) XY() (float64, float64) {
 	return p.X, p.Y
 }
 
-// ImageInfoType contains size, color and other information about an image
+// ImageInfoType contains size, color and other information about an image.
+// Changes to this structure should be reflected in its GobEncode and GobDecode
+// methods.
 type ImageInfoType struct {
 	data  []byte
 	smask []byte
@@ -176,99 +178,32 @@ type ImageInfoType struct {
 	dpi   float64
 }
 
-func (info *ImageInfoType) GobEncode() ([]byte, error) {
+// GobEncode encodes the receiving image to a byte slice.
+func (info *ImageInfoType) GobEncode() (buf []byte, err error) {
+	fields := []interface{}{info.data, info.smask, info.i, info.n, info.w, info.h, info.cs,
+		info.pal, info.bpc, info.f, info.dp, info.trns, info.scale, info.dpi}
 	w := new(bytes.Buffer)
 	encoder := gob.NewEncoder(w)
-
-	err := encoder.Encode(info.data)
-	if err == nil {
-		err = encoder.Encode(info.smask)
-	}
-	if err == nil {
-		err = encoder.Encode(info.i)
-	}
-	if err == nil {
-		err = encoder.Encode(info.n)
-	}
-	if err == nil {
-		err = encoder.Encode(info.w)
-	}
-	if err == nil {
-		err = encoder.Encode(info.h)
-	}
-	if err == nil {
-		err = encoder.Encode(info.cs)
-	}
-	if err == nil {
-		err = encoder.Encode(info.pal)
-	}
-	if err == nil {
-		err = encoder.Encode(info.bpc)
-	}
-	if err == nil {
-		err = encoder.Encode(info.f)
-	}
-	if err == nil {
-		err = encoder.Encode(info.dp)
+	for j := 0; j < len(fields) && err == nil; j++ {
+		err = encoder.Encode(fields[j])
 	}
 	if err == nil {
-		err = encoder.Encode(info.trns)
+		buf = w.Bytes()
 	}
-	if err == nil {
-		err = encoder.Encode(info.scale)
-	}
-	if err == nil {
-		err = encoder.Encode(info.dpi)
-	}
-
-	return w.Bytes(), err
+	return
 }
 
-func (info *ImageInfoType) GobDecode(buf []byte) error {
+// GobDecode decodes the specified byte buffer (generated by GobEncode) into
+// the receiving image.
+func (info *ImageInfoType) GobDecode(buf []byte) (err error) {
+	fields := []interface{}{&info.data, &info.smask, &info.i, &info.n, &info.w, &info.h,
+		&info.cs, &info.pal, &info.bpc, &info.f, &info.dp, &info.trns, &info.scale, &info.dpi}
 	r := bytes.NewBuffer(buf)
 	decoder := gob.NewDecoder(r)
-
-	err := decoder.Decode(&info.data)
-	if err == nil {
-		err = decoder.Decode(&info.smask)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.i)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.n)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.w)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.h)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.cs)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.pal)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.bpc)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.f)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.dp)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.trns)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.scale)
-	}
-	if err == nil {
-		err = decoder.Decode(&info.dpi)
+	for j := 0; j < len(fields) && err == nil; j++ {
+		err = decoder.Decode(fields[j])
 	}
-	return err
+	return
 }
 
 // PointConvert returns the value of pt, expressed in points (1/72 inch), as a
diff --git a/doc.go b/doc.go
index 02733ba..534b1d7 100644
--- a/doc.go
+++ b/doc.go
@@ -235,7 +235,10 @@ account when calculating image size. Paulo Coutinho provided support for static
 embedded fonts. Dan Meyers added support for embedded JavaScript. David Fish
 added a generic alias-replacement function to enable, among other things, table
 of contents functionality. Andy Bakun identified and corrected a problem in
-which the internal catalogs were not sorted stably.
+which the internal catalogs were not sorted stably. d1ngd0 added encoding and
+decoding functionality for templates, including images that are embedded in
+templates; this allows templates to be stored independently of gofpdf.
+
 
 Roadmap
 
diff --git a/fpdf_test.go b/fpdf_test.go
index 19bc533..68a26ad 100644
--- a/fpdf_test.go
+++ b/fpdf_test.go
@@ -1957,12 +1957,12 @@ func ExampleFpdf_CreateTemplate() {
 	pdf.AddPage()
 	pdf.UseTemplate(template3)
 	pdf.UseTemplateScaled(template3, gofpdf.PointType{X: 0, Y: 30}, tplSize)
-	pdf.UseTemplateScaled(template3, gofpdf.PointType{X: 0, Y: 60}, tplSize.ScaleBy(1.4))
 	pdf.Line(40, 210, 60, 210)
 	pdf.Text(40, 200, "Template example page 1")
 
 	pdf.AddPage()
 	pdf.UseTemplate(template2)
+	pdf.UseTemplateScaled(template3, gofpdf.PointType{X: 0, Y: 30}, tplSize.ScaleBy(1.4))
 	pdf.Line(60, 210, 80, 210)
 	pdf.Text(40, 200, "Template example page 2")
 
diff --git a/template_impl.go b/template_impl.go
index 1a91112..c34e688 100644
--- a/template_impl.go
+++ b/template_impl.go
@@ -82,7 +82,7 @@ func (t *FpdfTpl) Templates() []Template {
 	return t.templates
 }
 
-// Turn a template into a byte string for later deserialization
+// Serialize turns a template into a byte string for later deserialization
 func (t *FpdfTpl) Serialize() ([]byte, error) {
 	b := new(bytes.Buffer)
 	enc := gob.NewEncoder(b)
@@ -91,7 +91,8 @@ func (t *FpdfTpl) Serialize() ([]byte, error) {
 	return b.Bytes(), err
 }
 
-// Create a template from a previously serialized template
+// DeserializeTemplate creaties a template from a previously serialized
+// template
 func DeserializeTemplate(b []byte) (Template, error) {
 	tpl := new(FpdfTpl)
 	dec := gob.NewDecoder(bytes.NewBuffer(b))
@@ -116,6 +117,8 @@ func (t *FpdfTpl) childrenImages() map[string]*ImageInfoType {
 	return childrenImgs
 }
 
+// GobEncode encodes the receiving template into a byte buffer. Use GobDecode
+// to decode the byte buffer back to a template.
 func (t *FpdfTpl) GobEncode() ([]byte, error) {
 	w := new(bytes.Buffer)
 	encoder := gob.NewEncoder(w)
@@ -161,6 +164,7 @@ func (t *FpdfTpl) GobEncode() ([]byte, error) {
 	return w.Bytes(), err
 }
 
+// GobDecode decodes the specified byte buffer into the receiving template.
 func (t *FpdfTpl) GobDecode(buf []byte) error {
 	r := bytes.NewBuffer(buf)
 	decoder := gob.NewDecoder(r)