crunchlife

Ruby Fractal Library

Ryan Baxter — Thu, 03 Jul 2008 14:26:00 -0700

Last October, I wrote a small fractal rendering program in Ruby using the Shoes windowing toolkit written by why the lucky stiff. It’s sole purpose was to test Shoes. The code was painfully slow at rendering the Mandelbrot set, but it did, however, begin a small obsession of mine with fractals.

Since I haven’t been able to find a fractal library for Ruby, I decided to write one. Over the last two weeks I’ve written some code to generate both the Mandelbrot and Julia set fractals using the escape time algorithm. The code is still slow, but within a couple weeks I hope to replace the slow portions with inline C.

There may still be some bugs and I haven’t added any error handling, but here it is. An “almost” pure Ruby fractal library. Once this is cleaned up I’ll repost the code. I suppose a gem could be possible as well. Happy 4th!

fractals.rb

# RB

require 'rubygems'
require 'complex'
require 'png'

module Fractals
  module Fractal
    attr_accessor :begin_range, :end_range

    def initialize(begin_range, end_range)
      @begin_range, @end_range = begin_range, end_range
    end

    def draw(height=250, width=250, m=1.0,
      save_as=self.class.to_s.downcase + '.png')
        canvas = PNG::Canvas.new(height, width)

        # Find the complex coordinate for each pixel.
        0.upto(height - 1) { |y|
          i = (y * (@end_range.image - @begin_range.image) / height +
          @begin_range.image) * m
          0.upto(width - 1) { |x|
            r = (x * (@end_range.real - @begin_range.real) / width +
            @begin_range.real) * m
            if self.in_set?(Complex(r, i)) then
              canvas[x, y] = PNG::Color::Black
            else
              canvas[x, y] = fetch_color(self.last_iteration, self.max_iterations)
            end                    
          }
        }

        png = PNG.new(canvas)
        png.save(save_as)
    end  

    private
    def fetch_color(last_iteration, max_iterations)  
      divisor = 765*last_iteration/max_iterations
      case divisor
        when 0..254 then return PNG::Color.new(divisor%255, 0, 0, 255)
        when 255..509 then return PNG::Color.new(255, divisor%255, 0, 255)
        when 510..765 then return PNG::Color.new(255, 255, divisor%255, 255)
      end       
    end
  end

  class Julia
    include Fractal
    attr_accessor :seed, :bailout, :max_iterations
    attr_reader :last_iteration

    def initialize(seed=Complex(0.36, 0.1), bailout=2, max_iterations=100,
    begin_range=Complex(-2.25, -1.5), end_range=Complex(0.75, 1.5))
      super(begin_range, end_range)
      @seed, @bailout, @max_iterations = seed, bailout, max_iterations
    end

    def in_set?(z)
      @max_iterations.times { |i|
        z = z**2 + @seed
        if z > @bailout then
          @last_iteration = i
          return false
        end      
      }
      return true
    end
  end

  class Mandelbrot
    include Fractal  
    attr_accessor :bailout, :max_iterations
    attr_reader :last_iteration

    def initialize(bailout=5, max_iterations=100, begin_range=Complex(-2.25,
    -1.5), end_range=Complex(0.75, 1.5))
      super(begin_range, end_range)
      @bailout, @max_iterations = bailout, max_iterations
    end

    def in_set?(c)
      z = 0
      @max_iterations.times { |i|
        z = z**2 + c
        if z > @bailout then
          @last_iteration = i
          return false
        end            
      }
      return true
    end
  end
end

Using this library is as simple as the following:

require 'fractals'

mandelbrot = Fractals::Mandelbrot.new
mandelbrot.draw

Any suggestions/bug fixes can be posted here. Thanks.

These are a Few of My Favorite Things

Ryan Baxter — Fri, 20 Jun 2008 10:17:00 -0700

A few of my favorite applications published major releases this week. The most known being the Firefox web browser. On Tuesday, the Mozilla team launched version 3 of their flagship product, Mozilla Firefox. It includes many bug fixes and an enhanced bookmarking system (love it). Within 24 hours, Firefox wracked up over 8 million downloads making it the most downloaded software ever.

The venerable Wine (Wine Is Not an Emulator) project finally reached version 1.0. For those not familiar with Unix-like operating systems, Wine allows users to execute Microsoft Windows programs on Linux, Mac OS X, FreeBSD, and Solaris. It’s a must have for those who just can’t quite give up their favorite Windows software.

This may not be considered a major release, but the folks at reddit have announced the open-sourcing of their social news website, reddit.com. IMO reddit.com takes the best elements of both slashdot.org and digg.com and combines them to make something even better. Kudos reddit, Mozilla, and Wine!

IE7's Inanimate GIF

Ryan Baxter — Wed, 11 Jun 2008 05:06:00 -0700

Animated GIFs are most often used as activity indicators in modern AJAX (asynchronous JavaScript and XML) enabled websites. I decided to use a GIF (Graphic Interchange Format) from ajaxload.info on an application that I’ve been developing at work. The application performs server-side processing on files uploaded by employees. Processing time varies depending on the size of the file. Larger files take longer.

I wanted the animated GIF to appear when the file upload button was clicked so I placed the image within a DIV tag and hid it by setting a blank CSS display property. OnClick of the upload button, a JavaScript function toggled the display value to “block”, making the DIV appear. This worked as expected in Firefox and IE6, but not in IE7. The DIV appeared in IE7, but it’s GIF wasn’t moving.

A little googling turned up a helpful comment on Rick Strahl’s blog.

I’ve run into a problem with animated gifs inside of a hidden area of a Web page that is hidden with style.display=’none’. When the area is made visible again, in Internet Explorer this causes the image to not be displayed an animated GIF whatever I try. [sic]

Apparently IE7 doesn’t like to animate hidden GIFs. User submitted comments on Rick Strahl’s blog provided many solutions, but only a couple worked in my situation. The first uses the JavaScript setTimeout method to populate the image’s SRC attribute 200 ms after the function call. The second sets the DIV’s innerHTML to a string containing an IMG tag with the animated GIF.

<script language='javascript'> 
    function ShowLoading(elementId) 
    {
        document.getElementById(elementId).style.display = "block"; 
        setTimeout('document.images["loadingImage"].src = "../images/loading.gif"', 200); 
    } 
</script>

Neither solution is ideal, but setting the element’s innerHTML felt a little bit cleaner to me.

<script language='javascript'>
    function ShowLoading(elementId)
    {   
        var element = document.getElementById(elementId);    

        element.innerHTML = "<img src='../images/loading.gif'>";    
        element.style.display = "block";
    }
</script>

*IE7 may have animations disabled. Go to Tools > Internet Options > Advanced > Multimedia. Checking “Play animations in webpages” may affect how IE7 renders your animated GIFs.

Samba Network Shares with Nautilus in Hardy Heron Part 2

Ryan Baxter — Sun, 01 Jun 2008 16:07:00 -0700

Nearly a month ago I wrote about my problems connecting to the network shares of my Linksys NAS200 using Nautilus in Ubuntu, Hardy Heron. My fix was simple and it worked. Unfortunately, the solution’s WAF (Wife Acceptance Factor) was low. Apparently she didn’t think it was easy enough to execute smbmount from a Terminal window. Whatever :) I have since written a small shell script that is called from Session Startup.

Initially, the script failed to connect to my network shares because my wireless network connection hadn’t finished negotiating before the script was executed. I coded around this by creating a while loop that greps the output of a ping to my router. If successful, the mount_shares function is called. Otherwise. the thread will sleep for 10 seconds and try again.

#!/bin/bash

user="thorbardin/ryan%password"
root_dir="/home/ryan/Network Shares"

mount_shares() {
  public_dir="$root_dir"/"Public on Thorbardin"
  home_dir="$root_dir"/"Home on Thorbardin"

  [ -d "$public_dir" ] || mkdir -p "$public_dir"
  [ -d "$home_dir" ] || mkdir -p "$home_dir"

  smbmount "//192.168.1.105/public disk" "$public_dir" -o user="$user"
  smbmount "//192.168.1.105/ryan" "$home_dir" -o user="$user"
}

while [ 1 ]; do
  if ping -c2 192.168.1.1 2>&1 | grep ttl; then
    mount_shares

    exit 0   
  fi
  sleep 10
done

exit 0

I’m already thinking about rewriting this script so that it scans my network using smbtree and automatically mounts all available network shares. That’ll be Part 3!

Temporary Identity Impersonation in ASP.NET

Ryan Baxter — Tue, 27 May 2008 09:01:00 -0700

Uploading files in an ASP.NET application is relatively easy to do. Uploading to a remote machine is a little bit trickier, but certainly doable. I followed a set of instructions on aspalliance.com, but rather than declare an account to impersonate in my web.config file, I decided to do it in code. That way I could use impersonation only when needed and encapsulate it for later use.

I referred to an article on Microsoft’s Help and Support website about how to implement impersonation. Their code worked great, but I decided to put it in a class to help keep things DRY.

using System;
using System.Web;
using System.Web.Security;
using System.Security.Principal;
using System.Runtime.InteropServices;

namespace Utilities
{    
    public class ImpersonateUser
    {
        public const int LOGON32_LOGON_INTERACTIVE = 2;
        public const int LOGON32_PROVIDER_DEFAULT = 0;

        WindowsImpersonationContext impersonationContext;

        [DllImport("advapi32.dll")]
        public static extern int LogonUserA(String lpszUserName,
            String lpszDomain,
            String lpszPassword,
            int dwLogonType,
            int dwLogonProvider,
            ref IntPtr phToken);
        [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern int DuplicateToken(IntPtr hToken,
            int impersonationLevel,
            ref IntPtr hNewToken);

        [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern bool RevertToSelf();

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern bool CloseHandle(IntPtr handle);

        public bool ImpersonateValidUser(String userName, String domain, String password)
        {
            WindowsIdentity tempWindowsIdentity;
            IntPtr token = IntPtr.Zero;
            IntPtr tokenDuplicate = IntPtr.Zero;

            if (RevertToSelf())
            {
                if (LogonUserA(userName, domain, password, LOGON32_LOGON_INTERACTIVE,
                    LOGON32_PROVIDER_DEFAULT, ref token) != 0)
                {
                    if (DuplicateToken(token, 2, ref tokenDuplicate) != 0)
                    {
                        tempWindowsIdentity = new WindowsIdentity(tokenDuplicate);
                        impersonationContext = tempWindowsIdentity.Impersonate();
                        if (impersonationContext != null)
                        {
                            CloseHandle(token);
                            CloseHandle(tokenDuplicate);
                            return true;
                        }
                    }
                }
            }
            if (token != IntPtr.Zero)
                CloseHandle(token);
            if (tokenDuplicate != IntPtr.Zero)
                CloseHandle(tokenDuplicate);
            return false;
        }

        public void UndoImpersonation()
        {
            impersonationContext.Undo();
        }
    }
}

After referencing my Utilities namespace I was then able to impersonate the account required for uploading:

if (FileUpload1.HasFile)
{
    ImpersonateUser impersonateUser = new ImpersonateUser();

    if (impersonateUser.ImpersonateValidUser("userName", "", "password"))
    {
        FileUpload1.SaveAs(Server.MapPath("~/files/fileName.txt"));
        impersonateUser.UndoImpersonation();
    }
    else
    {
        throw new Exception("Identity impersonation has failed.");
    }   
}

*The SaveAs method of the FileUpload control requires a root path. Using Server.MapPath will provide the root path of your IIS virtual folder.

DIY Multi-Touch Pad

Ryan Baxter — Fri, 23 May 2008 09:04:00 -0700

A Plea to New Communities

Ryan Baxter — Wed, 21 May 2008 06:57:00 -0700

Mark Pilgrim, a Technical Writer at Google, explains his new project, Google DocType.

According to Mark, Google DocType will be an open resource for sharing web programming knowledge. As of today, it contains HOWTO articles on CSS (Cascading Style Sheets), DOM (Document Object Model) manipulation, and Web security. Links to CSS and HTML references round out the site’s content. I have no doubt that DocType is just the beginning for Google, but will this be just another W3Schools?

In numerous posts on codinghorror.com, Jeff Atwood has suggested that programmers no longer read books. Jeff believes the Internet is most programmers’ first reference choice. He has since announced a partnership with Joel Spolsky to create a community for developers. In his words:

There’s far too much great programming information trapped in forums, buried in online help, or hidden away in books that nobody buys any more. We’d like to unlock all that. Let’s create something that makes it easy to participate, and put it online in a form that is trivially easy to find.

My plea to both of these fledgling projects is best stated in the last sentence of the above quote. Please make the information trivially easy to find. I’m one of those developers using the Internet as a programming reference and I’m tired of searching for the proverbial needle in a haystack.

SEO (Search Engine Optimization) isn’t the only answer. Too many times keywords return results containing solutions for yesterday’s problems. What worked yesterday may not be today’s answer. Operating systems, software dependencies, and programming languages all change. How do we keep content relevant? Unfortunately I don’t have an answer to this problem, but perhaps Mark, Jeff, or Joel can come up with something profound. I wish them luck.

Rockscroll Visual Studio Add-in

Ryan Baxter — Tue, 13 May 2008 06:32:00 -0700

Last Friday, Scott Hanselman announced the release of the Rockscroll Visual Studio Add-in. Rockscroll replaces Visual Studio’s code-view scrollbar with a miniature visual representation of your source code. This feature makes navigation in large source files that much easier.

Before Rockscroll, I’d oftentimes make mental notes of the scrollbar’s position while traversing code. That, and when spending a lot of time on a project I’d become so familiar with the source code that I’d begin to recognize most code blocks by shape. Rockscroll provides both of these mnemonic devices, but with less brain work. That is a good thing. Thank you, Rocky Downs. Can I have this in NetBeans? :)

Quote of the Day

Ryan Baxter — Mon, 12 May 2008 08:01:00 -0700

XML is like violence. If it doesn’t solve your problem, you’re not using enough of it.

I got a chuckle out of reading this in a comment on Jeff Atwood’s latest post, XML: The Angle Bracket Tax. The quote is more than fitting for the XML I’ve been working with lately. For the severely twisted, check out the ODF (OpenDocument Format) and OpenXML (Office Open XML) document file formats.

A Few Date Methods

Ryan Baxter — Tue, 06 May 2008 11:45:00 -0700

An ASP.NET project of mine recently required the calculation of the start and end date of the current date’s previous month. This was more difficult putting into words than code. It did, however, get me thinking about other common date routines.

public static DateTime FirstDayOfPreviousMonth
{
    get
    {
        return new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1).AddMonths(-1);
    }    
}

public static DateTime LastDayOfPreviousMonth
{
    get
    {
        return new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1).AddDays(-1);
    }
}

Being preemptive, I decided to include a few methods for determining the start and end date of the current date’s fiscal quarter. I started by calculating the current date’s quarter. This was accomplished with just a little division.

public static int CurrentQuarter
{
    get
    {
        return (DateTime.Now.Month + 2) / 3;
    }
}

Finding the start and end dates of the current quarter was harder, but could still be expressed in a single line of code (or two).

public static DateTime FirstDayOfCurrentQuarter
{
    get
    {
        return new DateTime(DateTime.Now.Year, 1 + ((CurrentQuarter - 1) * 3), 1);
    }
}

public static DateTime LastDayOfCurrentQuarter
{
    get
    {
        int lastMonthOfCurrentQuarter = 3 + ((CurrentQuarter - 1) * 3);

        return new DateTime(DateTime.Now.Year, lastMonthOfCurrentQuarter, DateTime.DaysInMonth(DateTime.Now.Year, lastMonthOfCurrentQuarter));
    }
}

I’d like to extend this collection to include other common date routines. Feel free to post your date methods as comments if you’d like to share.

*The methods I’ve created for calculating the current quarter’s start and end dates assume the fiscal year starts on January 1st. This may not be suitable for your needs.

Samba Network Shares with Nautilus in Hardy Heron

Ryan Baxter — Mon, 28 Apr 2008 17:50:00 -0700

A couple of days ago I mentioned a few of my woes with the latest release of Ubuntu. Since then, I’ve installed Ruby on Rails and have found a work around for the continued problems I’ve had in accessing my samba shares using the “Connect to Server…” option in Nautilus. If you’re experiencing the symptoms described in bug report #208531, then you might want to give smbmount a try. From the command-line, type:

smbmount //{server}/{share} /home/{user}/{share} -o username={server_username}

To unmount the share:

sudo umount /home/{user}/{share}

I’m using this as a temporary solution until the bug in Nautilus is resolved. Your mileage may vary.

*The statements above were written under the assumption that you’ve created a folder within your home directory for mounting the share.

Ruby on Rails with Hardy Heron

Ryan Baxter — Sat, 26 Apr 2008 14:20:00 -0700

This Thursday, Canonical released Ubuntu, Hardy Heron, into the wild. Like many others, I immediately fired up a torrent and began downloading. From what I read of the aftermath, many launch day downloaders were not as lucky. Most Torrent servers became immediately inaccessible due to Hardy Heron’s popular demand. It has been three days and the US update servers are still saturated. This happens every release and can only mean that Ubuntu’s userbase is steadily growing.

My installation went well, but with any new OS release comes problems and Hardy Heron was not an exception. I couldn’t connect to my NAS through Nautilus. None of my browser extensions worked and Ruby on Rails was MIA. I decided to fix Rails first. Here are the steps I took to install Ruby on Rails on Ubuntu, Hardy Heron.

sudo apt-get install ruby

At this point I could not install Ruby on Rails with RubyGems because of the following exception:

/usr/bin/gem:23: uninitialized constant Gem::GemRunner(NameError)

I opened up the source file and edited the offending line.

sudo gedit /usr/bin/gem

Adding require ‘rubygems/gem_runner’ to the source file,

require 'rubygems'
require 'rubygems/gem_runner'

I was then able to update RubyGems

sudo gem install rubygems-update

and install Ruby on Rails and the Mongrel web server.

sudo gem install rails mongrel

At this point I had a working version of Rails on my installation of Ubuntu, Hardy Heron. To get back to work the only thing missing was the NetBeans Ruby IDE. If you haven’t tried NetBeans for your Ruby on Rails projects, I highly recommend it. It’s located in the repos and only takes a few plugins to have Rails support out of the box.

Festo Air Jelly

Ryan Baxter — Thu, 24 Apr 2008 13:08:00 -0700

Amazing. I’d love to see more natural design in programming languages.

System.Drawing.Color Hex Values

Ryan Baxter — Wed, 16 Apr 2008 16:29:00 -0700

Do you know the hexidecimal value of PapayaWhip? How about BlanchedAlmond? Me either. I’m not a big fan of the System.Drawing.Color structure in the Microsoft .NET Framework. I don’t think the addition of color names makes good framework design sense. Unless you’re an Interior Designer; the majority of these colors won’t make sense to you either.

I’ve recently spent time reworking a few design elements of an ASP.NET website. All design related ASP.NET attributes were replaced with Cascading Style Sheets (CSS) where applicable. Unfortunately the website was spattered with named colors from the System.Drawing.Color structure. To help replace these named colors with hexadecimal values, I found the following resource extremely helpful.

http://www.opinionatedgeek.com/DotNet/Tools/Colors/default.aspx