Add image cropping. (#4117)

weed/images/cropping.go

@@ -0,0 +1,47 @@
+package images
+
+import (
+	"bytes"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"io"
+
+	"github.com/disintegration/imaging"
+
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+)
+
+func Cropped(ext string, read io.ReadSeeker, x1, y1, x2, y2 int) (cropped io.ReadSeeker, err error) {
+	srcImage, _, err := image.Decode(read)
+	if err != nil {
+		glog.Error(err)
+		return read, err
+	}
+
+	bounds := srcImage.Bounds()
+	if x2 > bounds.Dx() || y2 > bounds.Dy() {
+		read.Seek(0, 0)
+		return read, nil
+	}
+
+	rectangle := image.Rect(x1, y1, x2, y2)
+	dstImage := imaging.Crop(srcImage, rectangle)
+	var buf bytes.Buffer
+	switch ext {
+	case ".jpg", ".jpeg":
+		if err = jpeg.Encode(&buf, dstImage, nil); err != nil {
+			glog.Error(err)
+		}
+	case ".png":
+		if err = png.Encode(&buf, dstImage); err != nil {
+			glog.Error(err)
+		}
+	case ".gif":
+		if err = gif.Encode(&buf, dstImage, nil); err != nil {
+			glog.Error(err)
+		}
+	}
+	return bytes.NewReader(buf.Bytes()), err
+}

weed/images/cropping_test.go

@@ -0,0 +1,22 @@
+package images
+
+import (
+	"bytes"
+	"os"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/util"
+)
+
+func TestCropping(t *testing.T) {
+	fname := "sample1.jpg"
+
+	dat, _ := os.ReadFile(fname)
+
+	cropped, _ := Cropped(".jpg", bytes.NewReader(dat), 1072, 932, 1751, 1062)
+	buf := new(bytes.Buffer)
+	buf.ReadFrom(cropped)
+
+	util.WriteFile("cropped1.jpg", buf.Bytes(), 0644)
+
+}