accept "fit" option

this also relaxes option parsing to never return an error.  In cases
where options are not able to be parsed, they are silently ignored.

data/data.go

@@ -2,7 +2,6 @@
 package data
 
 import (
-	"errors"
 	"fmt"
 	"net/url"
 	"strconv"
@@ -15,18 +14,24 @@ import (
 type Options struct {
 	Width  int // requested width, in pixels
 	Height int // requested height, in pixels
+
+	// If true, resize the image to fit in the specified dimensions.  Image
+	// will not be cropped, and aspect ratio will be maintained.
+	Fit bool
 }
 
 func (o Options) String() string {
 	return fmt.Sprintf("%dx%d", o.Width, o.Height)
 }
 
-func ParseOptions(str string) (*Options, error) {
+func ParseOptions(str string) *Options {
-	t := new(Options)
+	o := new(Options)
-	var err error
 	var h, w string
 
-	size := strings.SplitN(str, "x", 2)
+	parts := strings.Split(str, ",")
+
+	// parse size
+	size := strings.SplitN(parts[0], "x", 2)
 	w = size[0]
 	if len(size) > 1 {
 		h = size[1]
@@ -35,19 +40,19 @@ func ParseOptions(str string) (*Options, error) {
 	}
 
 	if w != "" {
-		t.Width, err = strconv.Atoi(w)
+		o.Width, _ = strconv.Atoi(w)
-		if err != nil {
-			return nil, errors.New("width must be an int")
-		}
 	}
 	if h != "" {
-		t.Height, err = strconv.Atoi(h)
+		o.Height, _ = strconv.Atoi(h)
-		if err != nil {
+	}
-			return nil, errors.New("height must be an int")
+
+	for _, part := range parts[1:] {
+		if part == "fit" {
+			o.Fit = true
 		}
 	}
 
-	return t, nil
+	return o
 }
 
 type Request struct {

proxy/proxy.go

@@ -46,10 +46,7 @@ func NewRequest(r *http.Request) (*data.Request, error) {
 			return nil, URLError{fmt.Sprintf("unable to parse remote URL: %v", err), r.URL}
 		}
 
-		req.Options, err = data.ParseOptions(parts[0])
+		req.Options = data.ParseOptions(parts[0])
-		if err != nil {
-			return nil, URLError{err.Error(), r.URL}
-		}
 	}
 
 	if !req.URL.IsAbs() {

proxy/proxy_test.go

@@ -30,11 +30,15 @@ func TestNewRequest(t *testing.T) {
 		{
 			"http://localhost//ftp://example.com/foo", "", nil, true,
 		},
+
+		// invalid options.  These won't return errors, but will not fully parse the options
 		{
-			"http://localhost/s/http://example.com/", "", nil, true,
+			"http://localhost/s/http://example.com/",
+			"http://example.com/", emptyOptions, false,
 		},
 		{
-			"http://localhost/1xs/http://example.com/", "", nil, true,
+			"http://localhost/1xs/http://example.com/",
+			"http://example.com/", &data.Options{Width: 1}, false,
 		},
 
 		// valid URLs
@@ -66,15 +70,23 @@ func TestNewRequest(t *testing.T) {
 		},
 		{
 			"http://localhost/1x/http://example.com/",
-			"http://example.com/", &data.Options{1, 0}, false,
+			"http://example.com/", &data.Options{1, 0, false}, false,
 		},
 		{
 			"http://localhost/x1/http://example.com/",
-			"http://example.com/", &data.Options{0, 1}, false,
+			"http://example.com/", &data.Options{0, 1, false}, false,
 		},
 		{
 			"http://localhost/1x2/http://example.com/",
-			"http://example.com/", &data.Options{1, 2}, false,
+			"http://example.com/", &data.Options{1, 2, false}, false,
+		},
+		{
+			"http://localhost/,fit/http://example.com/",
+			"http://example.com/", &data.Options{0, 0, true}, false,
+		},
+		{
+			"http://localhost/1x2,fit/http://example.com/",
+			"http://example.com/", &data.Options{1, 2, true}, false,
 		},
 	}
 

transform/transform.go

@@ -18,6 +18,14 @@ var emptyOptions = new(data.Options)
 // Transform the provided image.
 func Transform(img data.Image, opt *data.Options) (*data.Image, error) {
 	if opt == nil || reflect.DeepEqual(opt, emptyOptions) {
+		// bail if no transformation was requested
+		return &img, nil
+	}
+
+	if opt.Width == 0 && opt.Height == 0 {
+		// TODO(willnorris): Currently, only resize related options are
+		// supported, so bail if no sizes are specified.  Remove this
+		// check if we ever support non-resizing transformations.
 		return &img, nil
 	}
 
@@ -28,8 +36,10 @@ func Transform(img data.Image, opt *data.Options) (*data.Image, error) {
 	}
 
 	// resize
-	if opt.Width != 0 || opt.Height != 0 {
+	if opt.Fit {
 		m = imaging.Fit(m, opt.Width, opt.Height, imaging.Lanczos)
+	} else {
+		m = imaging.Resize(m, opt.Width, opt.Height, imaging.Lanczos)
 	}
 
 	// encode image