[gegl] Add a python example that uses the Node API

[Daniel Sabo <daniels src gnome org>]

commit 91cd71a27b2cce29f3fcda00518e13eae6586108
Author: Daniel Sabo <DanielSabo gmail com>
Date:   Tue Jun 4 04:55:11 2013 -0700

    Add a python example that uses the Node API

 examples/simple-graph.py |   47 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 47 insertions(+), 0 deletions(-)
---
diff --git a/examples/simple-graph.py b/examples/simple-graph.py
new file mode 100755
index 0000000..13c3658
--- /dev/null
+++ b/examples/simple-graph.py
@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+
+from gi.repository import Gegl
+from gi.repository import GObject
+
+if __name__ == '__main__':
+  Gegl.init(0,"")
+  
+  ptn = Gegl.Node()
+  
+  # Disable caching on all child nodes
+  GObject.Object.set_property(ptn, "dont-cache", True)
+  
+  
+  # Create our background buffer. A gegl:color node would
+  # make more sense, we just use a buffer here as an example.
+  background_buffer = Gegl.Buffer.new("RGBA float", 246, -10, 276, 276)
+  white = Gegl.Color.new("#FFF")
+  background_buffer.set_color(background_buffer.get_extent(), white)
+  
+  src = ptn.create_child("gegl:load")
+  src.set_property("path", "data/surfer.png")
+  
+  crop = ptn.create_child("gegl:crop")
+  crop.set_property("x", 256)
+  crop.set_property("y", 0)
+  crop.set_property("width", 256)
+  crop.set_property("height", 256)
+  
+  buffer_src = ptn.create_child("gegl:buffer-source")
+  buffer_src.set_property("buffer",background_buffer)
+  
+  over = ptn.create_child("gegl:over")
+  
+  dst = ptn.create_child("gegl:save")
+  dst.set_property("path", "cropped.png")
+  
+  # The parent node is only for reference tracking, we need to
+  # connect the node's pads to actualy pass data between them.
+  buffer_src.connect_to("output", over, "input")
+  src.connect_to("output", crop, "input")
+  crop.connect_to("output", over, "aux")
+  over.connect_to("output", dst, "input")
+  
+  # Will create "cropped.png" in the current directory
+  dst.process()
+