From ce5b36a6cb4ea4fdcae29b197c4609d7e189c3af Mon Sep 17 00:00:00 2001
From: Will Charczuk <will@blendlabs.com>
Date: Sat, 27 Aug 2016 14:23:55 -0700
Subject: [PATCH] image collector.

---
 _examples/image_writer/main.go | 27 +++++++++++++++++++++++++++
 raster_renderer.go             |  4 ++++
 2 files changed, 31 insertions(+)
 create mode 100644 _examples/image_writer/main.go

diff --git a/_examples/image_writer/main.go b/_examples/image_writer/main.go
new file mode 100644
index 0000000..13bf013
--- /dev/null
+++ b/_examples/image_writer/main.go
@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/wcharczuk/go-chart"
+)
+
+func main() {
+	graph := chart.Chart{
+		Series: []chart.Series{
+			chart.ContinuousSeries{
+				XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
+				YValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
+			},
+		},
+	}
+	collector := &chart.ImageWriter{}
+	graph.Render(chart.PNG, collector)
+
+	image, err := collector.Image()
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Final Image: %dx%d\n", image.Bounds().Size().X, image.Bounds().Size().Y)
+}
diff --git a/raster_renderer.go b/raster_renderer.go
index 3b9fa4d..1b0cf96 100644
--- a/raster_renderer.go
+++ b/raster_renderer.go
@@ -210,5 +210,9 @@ func (rr *rasterRenderer) ClearTextRotation() {
 
 // Save implements the interface method.
 func (rr *rasterRenderer) Save(w io.Writer) error {
+	if typed, isTyped := w.(RGBACollector); isTyped {
+		typed.SetRGBA(rr.i)
+		return nil
+	}
 	return png.Encode(w, rr.i)
 }