From 3534362c0523a686e558ab3cbe7ad90abe06d11e Mon Sep 17 00:00:00 2001
From: Mauro Romano Trajber <mauro@registro.br>
Date: Mon, 10 Aug 2015 14:32:34 -0300
Subject: [PATCH] provide a way to write PNG image file data to a buffer (byte
 array)

---
 gd.go | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/gd.go b/gd.go
index ddade3b..2536b39 100755
--- a/gd.go
+++ b/gd.go
@@ -73,6 +73,17 @@ func ImageToJpegBuffer(p *Image, quality int) []byte {
 	return C.GoBytes(buf, *pimgSize)
 }
 
+func ImageToPngBuffer(p *Image) []byte {
+	var imgSize int
+	pimgSize := (*C.int)(Pointer(&imgSize))
+
+	buf := C.gdImagePngPtr(p.img, pimgSize)
+	defer C.gdFree(buf)
+
+	return C.GoBytes(buf, *pimgSize)
+}
+
+
 func CreateFromJpeg(infile string) *Image {
 	file := C.fopen(C.CString(infile), C.CString("rb"))