Update doc string for ImageCommandResult, and add Example usage of Co…

…nvertImageCommand (refs #220)

imagick/image.go

@@ -38,6 +38,9 @@ func NewMagickImage(info *ImageInfo, width, height uint,
 	return &Image{img: img}, nil
 }
 
+// ImageCommandResult is returned by a call to
+// ConvertImageCommand. It contains the ImageInfo
+// and Metadata string generated by the convert command.
 type ImageCommandResult struct {
 	Info *ImageInfo
 	Meta string
@@ -47,13 +50,7 @@ type ImageCommandResult struct {
 ConvertImageCommand reads one or more images, applies one or more image
 processing operations, and writes out the image in the same or differing
 format.
-
-A description of each parameter follows:
-   * image_info: the image info.
-   * argc: the number of elements in the argument vector.
-   * argv: A text array containing the command line arguments.
-   * metadata: any metadata is returned here.
-   * exception: return any errors or warnings in this structure.
+The first item in the args list is expected to be the program name, ie "convert".
 */
 func ConvertImageCommand(args []string) (*ImageCommandResult, error) {
 	size := len(args)

imagick/image_test.go

@@ -5,6 +5,7 @@
 package imagick
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"testing"
@@ -31,6 +32,16 @@ func TestNewMagickImage(t *testing.T) {
 	}
 }
 
+func ExampleConvertImageCommand() {
+	ret, err := ConvertImageCommand([]string{
+		"convert", "logo:", "-resize", "100x100", "/tmp/out.png",
+	})
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println("Meta:", ret.Meta)
+}
+
 func TestConvertImageCommand(t *testing.T) {
 	tmp, err := ioutil.TempFile("", "imagick_test")
 	if err != nil {