move data structures to data package

also use io.Copy to copy fetched image to http.ResponseWriter.

data/data.go

@@ -0,0 +1,55 @@
+// Package data provides common shared data structures for go-imageproxy.
+package data
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+// Transform specifies transformations that can be performed on a
+// requested image.
+type Transform struct {
+	Width  int `json:"width"`  // requested width, in pixels
+	Height int `json:"height"` // requested height, in pixels
+}
+
+func (o Transform) String() string {
+	return fmt.Sprintf("%dx%d", o.Width, o.Height)
+}
+
+func ParseTransform(str string) (*Transform, error) {
+	t := new(Transform)
+	var err error
+	var h, w string
+
+	size := strings.SplitN(str, "x", 2)
+	w = size[0]
+	if len(size) > 1 {
+		h = size[1]
+	} else {
+		h = w
+	}
+
+	if w != "" {
+		t.Width, err = strconv.Atoi(w)
+		if err != nil {
+			return nil, errors.New("width must be an int")
+		}
+	}
+	if h != "" {
+		t.Height, err = strconv.Atoi(h)
+		if err != nil {
+			return nil, errors.New("height must be an int")
+		}
+	}
+
+	return t, nil
+}
+
+type Request struct {
+	URL       *url.URL   // URL of the image to proxy
+	Transform *Transform // Image transformation to perform
+}