Added some comments to new encoding/decoding methods

1 files changed, 19 insertions, 84 deletions

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