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Using NodeBox in another application

The NodeBox core is now split off from the UI functionality, so you can use it in any project. There are a few different ways of using NodeBox.

1. The easy way: from NodeBox itself

One of the new features in NodeBox is that you can access the canvas object. It's a list-like structure, containing all your graphical objects ("grobs"). The canvas also has a "save" method, so anywhere in your script you can do:

canvas.save("partial.pdf")

And it will save what it has drawn up until that point. Do it at the end of your script, and you get the full output.

After saving, you might want to clear out the canvas. You can:

canvas.clear()

This will remove all grobs already on the canvas; they will not show up in the render.

2. Installing the NodeBox module

If you want to use NodeBox from the command line, you will have to install it. We currently recommend using Subversion to grab a copy:

svn co http://dev.nodebox.net/svn/nodebox/trunk/ nodebox
cd libs/Numeric
python setup.py install
cd ../..
 
cd libs/pathmatics
python setup.py install
cd ../..
 
cd libs/polymagic
python setup.py install
cd ../..
 
cd src
python setup.py install

The only outside dependency is PyObjC. We recommend the latest version from Subversion.

3. Using the console runner

When you have a set of NodeBox scripts that you want to run to generate images or a movie, use the following commands:

from nodebox import console
source = "size(200,200)\nrect(random(WIDTH), random(HEIGHT), 20, 20)"
console.make_image(source, "rect.png")
console.make_movie(source, "rect.mov", 20, fps=30)

Currently, there is no way to run the console from the command line, but we're working on that.

4. Accessing the context directly

If you want to have direct access to NodeBox's drawing context, you can import everything directly. The API remains the same, but you have to prefix everything with the context. Note also the initialization of Cocoa, necessary for using the API.

from AppKit import NSApplication
NSApplication.sharedApplication().activateIgnoringOtherApps_(0)
 
from nodebox.graphics import Context
from nodebox.util import random, choice, grid, files
ctx = Context()
ctx.size(200, 200)
ctx.rect(random(ctx.WIDTH), random(ctx.HEIGHT), 100, 100)
ctx.save("test.png")

You can also make movies this way:

from AppKit import NSApplication
NSApplication.sharedApplication().activateIgnoringOtherApps_(0)
 
from nodebox.graphics import Context
from nodebox.util import random, choice, grid, files
from nodebox.util.QTSupport import Movie
 
movie = Movie("rects.mov")
for i in range(10):
   ctx = Context()
    ctx.size(200, 200)
 ctx.rect(random(ctx.WIDTH), random(ctx.HEIGHT), 100, 100)
  movie.add(ctx)
movie.save()

5. Drawing in a Cocoa drawRect method

If you want to implement your existing drawing using NodeBox, you can do the following in your class's drawRect: method:

def drawRect_(self, rect):
    from nodebox.graphics import Context
   from nodebox.util import random
    ctx.size(*rect[1])
 ctx.rect(random(ctx.WIDTH), random(ctx.HEIGHT), 100, 100)
  ctx.canvas.draw()

Note that creating the Context and drawing it are two separate steps:

• First, the context is created; all drawing commands are translated into graphic objects ("grobs") that are stored on the canvas.
• Then, the canvas is drawn; each grob now renders itself on the current Cocoa graphics context.

This also means you can cache the context (or the canvas) and use it in a drawRect method during a later stage.