From e48c3dd6cf186b398640d1f39ff444e5125a6480 Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Thu, 26 Jan 2017 23:31:06 +0100
Subject: [PATCH] clarify doc

---
 picture.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/picture.go b/picture.go
index 17569ac..db35f28 100644
--- a/picture.go
+++ b/picture.go
@@ -57,6 +57,8 @@ func PictureFromTexture(tex *pixelgl.Texture) *Picture {
 }
 
 // Image returns the content of the Picture as an image.NRGBA.
+//
+// Note, that this operation can be rather expensive.
 func (p *Picture) Image() *image.NRGBA {
 	bounds := p.Bounds()
 	nrgba := image.NewNRGBA(image.Rect(0, 0, int(bounds.W()), int(bounds.H())))