Merge pull request #1 from j-mcnally/Feature/Pad

allow images to be padded to properly fit requested dimensions

data.go

@@ -26,6 +26,7 @@ import (
 
 const (
 	optFit             = "fit"
+	optPad             = "pad"
 	optFlipVertical    = "fv"
 	optFlipHorizontal  = "fh"
 	optFormatJPEG      = "jpeg"
@@ -63,6 +64,9 @@ type Options struct {
 	// will not be cropped, and aspect ratio will be maintained.
 	Fit bool
 
+	// If true we will pad the image to requested dimensions
+	Pad bool
+
 	// Rotate image the specified degrees counter-clockwise.  Valid values
 	// are 90, 180, 270.
 	Rotate int
@@ -98,6 +102,9 @@ func (o Options) String() string {
 	if o.Fit {
 		opts = append(opts, optFit)
 	}
+	if o.Pad {
+		opts = append(opts, optPad)
+	}
 	if o.Rotate != 0 {
 		opts = append(opts, fmt.Sprintf("%s%d", optRotatePrefix, o.Rotate))
 	}
@@ -255,6 +262,8 @@ func ParseOptions(str string) Options {
 		case len(opt) == 0: // do nothing
 		case opt == optFit:
 			options.Fit = true
+		case opt == optPad:
+			options.Pad = true
 		case opt == optFlipVertical:
 			options.FlipVertical = true
 		case opt == optFlipHorizontal:

transform.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"fmt"
 	"image"
+	"image/color"
 	_ "image/gif" // register gif format
 	"image/jpeg"
 	"image/png"
@@ -320,5 +321,14 @@ func transformImage(m image.Image, opt Options) image.Image {
 		m = imaging.FlipH(m)
 	}
 
+	if opt.Pad {
+		originalWidth := m.Bounds().Max.X
+		newCenter := (w / 2) - (originalWidth / 2)
+
+		m2 := imaging.New(w, h, color.NRGBA{255, 255, 255, 255})
+		m2 = imaging.Paste(m2, m, image.Pt(newCenter, 0))
+		m = m2
+	}
+
 	return m
 }