From 78e6288748e0076269c3e65a479b6ba72be61f1d Mon Sep 17 00:00:00 2001
From: Will Charczuk <will@blendlabs.com>
Date: Sat, 27 Aug 2016 14:24:15 -0700
Subject: [PATCH] image collector

---
 image_writer.go | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 image_writer.go

diff --git a/image_writer.go b/image_writer.go
new file mode 100644
index 0000000..b4ddb7a
--- /dev/null
+++ b/image_writer.go
@@ -0,0 +1,41 @@
+package chart
+
+import (
+	"bytes"
+	"errors"
+	"image"
+	"image/png"
+)
+
+type RGBACollector interface {
+	SetRGBA(i *image.RGBA)
+}
+
+// ImageWriter is a special type of io.Writer that produces a final image.
+type ImageWriter struct {
+	rgba     *image.RGBA
+	contents *bytes.Buffer
+}
+
+func (ir *ImageWriter) Write(buffer []byte) (int, error) {
+	if ir.contents == nil {
+		ir.contents = bytes.NewBuffer([]byte{})
+	}
+	return ir.contents.Write(buffer)
+}
+
+// SetRGBA sets a raw version of the image.
+func (ir *ImageWriter) SetRGBA(i *image.RGBA) {
+	ir.rgba = i
+}
+
+// Image returns an *image.Image for the result.
+func (ir *ImageWriter) Image() (image.Image, error) {
+	if ir.rgba != nil {
+		return ir.rgba, nil
+	}
+	if ir.contents != nil && ir.contents.Len() > 0 {
+		return png.Decode(ir.contents)
+	}
+	return nil, errors.New("No valid sources for image data, cannot continue.")
+}