Adding LOC to the web.

Cairo is a 2D vector graphics api used by Firefox, Gtk and other desktop projects.

I’m going to show here that it can also be used to generate web content, using Django.

I’m going to port two examples from the Michael Urmans Cairo Tutorial for PyGTK Programmers.

To understand the cairo and it’s drawing model I’d recommend his his Cairo Tutorial for Python Programmers.

Note: In this example I’ll be generating SVGs…  as I.E. (as of 2010) does not support them, you might want to generate PNG or PDF – if you need to do this with cairo, look for one of the many cairo tutorials on the web.

The example django project can be downloaded at the end of the article.

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I recently found a neat way of accessing files in a linux VMWare image.   This is really useful, as theres never really a good time to break your VMWare image, this is also handy if you don’t want to run the whole machine, but just access the files inside.

There is one caveat:

• It only works if the filesystem is ext2 (ext3 works, and ext4 probably works).

Install VMWare DiskMount Utility

Accept the EULA, download and install the VMWare DiskMount utility.

For convenience add the utilities folder to the path:

C:\Program Files\VMware\VMware DiskMount Utility

Do this through the Windows Gui, or even use my addpath utility.

At this point you can mount Windows VMWare images.

The usage is:  vmware-mount drive-letter vmdk-image.

Heres how I mount my Ubuntu image to the j: drive

[C:\vmware\Ubuntu]vmware-mount j: ubuntu.vmdk

[C:\vmware\Ubuntu]

No output here indicates success.

At this point everything seems fine, but a crucial piece of the puzzle is still missing; try and view the files and you still can’t:

The next step is to make Windows understand the ext2 filesystem, using a special driver.

Install ext2ifs

Grab ext2ifs from www.fs-driver.org and install.

If the following steps don’t work then you may need to reboot.

Thats it!

You should be now able to access files inside your VMWare image (assuming it’s ext2 and not reiserfs), remount the image and have a go:

In my case I did:

[C:\vmware\Ubuntu]vmware-mount j: ubuntu.vmdk

[C:\vmware\Ubuntu] dir j:

Heres the output – hooray, I can copy my work out of the image !

This is very useful, especially if you do dist-upgrade in ubuntu and can’t access the network.

Bonus tip:

Newer versions of VMWare player let you install VMWare tools from inside the GUI, this is another way to fix the kind of catestrophic problems you can cause yourself by accidentally upgrading the kernel in an image.

I recently came across Java2Python.  As I’m interested in Cairo I thought it would be interesting to try porting one of the example tutorials from ZetCode.

I’ll run through the steps involved in porting then try and reach some conclusions at the end .

1. Get setup

This is easiest in Linux, I’m running Ubuntu (in vmware), and installed

antlr 2.x
python2.5.x
sun java6
pygtk
java-gnome

You can install them like this:

# sudo apt-get install antlr python2.5 sun-java6-bin libjava-gnome-java

Then install Python2Java with easy_install

# sudo easy_install-2.5 java2python

To test if it’s working run j2py -i.  It should complain there is no file:

# j2py -i
Usage: j2py [options]

j2py: error: -i option requires an argument

If you get any other errors your missing some packages.

2. Get the Java Code from the Simple Example.

Save the ’simple.java’ example as ‘GSimple.java’

If java-gnome is running ok, compiling and running it you should see a window:

# javac GSimple.java
# java GSimple

Lyrics

A lot of information on the web is aimed at people who use flashdevelop and other guis to build flex apps, this article is aimed at developers.  I’ll give you the information to get started with flex development quickly, using the free sdk and building with ant from the commandline.

A passing knowledge of ant wouldn’t hurt either.

This tutorial uses the file blankapp.zip to help bootstrap you into the world of flex / actionscript development.

Prerequisites

Flex SDK

You will need the flex sdk available from the flex developer center

Apache ant

You will need apache ant, make sure that the bin folder is in your path.

Copy flexTasks.jar from the flex ant lib into your own ant lib folder.

Setup

Extract the blankapp.zip to a folder

Open build.xml and change the line <property name=”FLEX_HOME” value=”/usr/flex/sdk3″ /> to point to the flex sdk.

Build

You can build it by typing

ant build

You should see some output like this

Buildfile: build.xml

clean:
   [delete] Deleting directory C:\Documents and Settings\Stuart\Desktop\projects\flex\blankapp\build

init:
    [mkdir] Created dir: C:\Documents and Settings\Stuart\Desktop\projects\flex\blankapp\build

build:
    [mxmlc] Loading configuration file C:\usr\flex\sdk3\frameworks\flex-config.xml
    [mxmlc] Initial setup: 172ms
    [mxmlc] Loaded 8 SWCs: 391ms
    [mxmlc] C:\Documents and Settings\Stuart\Desktop\projects\flex\blankapp\src\blankapp_333027.cache (The system cannot
 find the file specified)
    [mxmlc] Files: 328 Time: 1562ms
    [mxmlc] Linking... 16ms
    [mxmlc] Optimizing... 125ms
    [mxmlc] SWF Encoding... 47ms
    [mxmlc] C:\Documents and Settings\Stuart\Desktop\projects\flex\blankapp\build\blankapp.swf (159158 bytes)
    [mxmlc] Persisting 33 compilation units... 15ms
    [mxmlc] Total time: 2328ms
    [mxmlc] Peak memory usage: 59 MB (Heap: 33, Non-Heap: 26)

BUILD SUCCESSFUL
Total time: 2 seconds

A new file, blankapp.swf should now be in the build folder

Type

ant deploy

To copy it to the deploy directory (later you can customise this later).

If you open the blankapp.swf in the browser you should see something like this

It’s fairly bare, but demonstrates some basic techniques and a couple of widgets.

Mxml and Actionscript, how they link together

There are two important parts, the blankapp.mxml and org/blankapp/BlankApp.as.

The mxml file defines the layout while the actionscript contains code to be executed.   In this case there is one mxml file, BlankApp.mxml which links to a single actionscript class, BlankApp (in the file src/org/blankapp/BlankApp.as).

The directory structure org/blankapp, defines the package, in much the same way as java packages.

The graphic below shows how the class is linked to the mxml and where the instance of the class is:

The app is very basic, but should provide a jumping off point.

Adding libraries

If you need to add any libraries, just place the swc files in the lib folder and they will be included, the build.xml can be changed if this isn’t satisfactory.

Afterword

I only wanted to get started with papervision, but found it a bit of hassle to get started, hopefully this post will help people get started quickly.

Acknowledgements

The ant build file is by no means my own, owes inspiration to previous ant files I’ve known, including the pyAMF one and information available on the web.

This blog entry: http://talsma.tv/post.cfm/ant-mxmlc-and-swc-files for the info on how to include swc files.