Add Save and Load util function

fileutil.go

@@ -0,0 +1,46 @@
+package draw2d
+
+import (
+	"bufio"
+	"image"
+	"image/png"
+	"os"
+)
+
+// SaveToPngFile create and save an image to a file using PNG format
+func SaveToPngFile(filePath string, m image.Image) error {
+	// Create the file
+	f, err := os.Create(filePath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	// Create Writer from file
+	b := bufio.NewWriter(f)
+	// Write the image into the buffer
+	err = png.Encode(b, m)
+	if err != nil {
+		return err
+	}
+	err = b.Flush()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// LoadFromPngFile Open a png file
+func LoadFromPngFile(filePath string) (image.Image, error) {
+	// Open file
+	f, err := os.OpenFile(filePath, 0, 0)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	b := bufio.NewReader(f)
+	img, err := png.Decode(b)
+	if err != nil {
+		return nil, err
+	}
+	return img, nil
+}