png code

Patchwork quilt pattern in Ruby (from Knuth TAoCP 4 - 7.1.3)

In Donald Knuth's TAoCP Pre-Fascicle 1a: Bitwise Tricks and Techniques, he shows a patchwork quilt defined by f(x, y) = ((x ^ y) & ((y - 350) >> 3)) ** 2, designed by D. Sleator in 1976. I wanted to recreate this quilt myself using Ruby. The following program generates a PNG file of the "quilt."

require 'rubygems'
require 'png'

def f(x, y)
  ( (x ^ y) & ((y - 350) >> 3) ) ** 2
end

canvas = PNG::Canvas.new(500, 500)

0.upto(499) do |y|
  0.upto(499) do |x|
    canvas[x, 499 - y] = ((f(x, y) >> 12) & 1) == 1 ? PNG::Color::Black : PNG::Color::White
  end
end

png = PNG.new(canvas)
png.save 'pattern.png'

to ruby graphics png knuth taocp sleator quilt by peter on Feb 27, 2008

dynamic rails img headers

// description of your code here

find views -name [a-z]\*rhtml | xargs -n1 grep -H "@page_title" | grep -v "<%" | sed "s/\@page_title = //" | sed "s/rhtml/png/" | sed "s:views/::" | sed "s:/:_:g" | sed "s:^:public/images/beta/headers/hdr_:" | sed "s/  //g"

to rails imagemagick bash shell dynamic png graphic header jm3 by jm3 on Nov 05, 2007

PNG-24 Alpha support for IE

What so much webdesigners dream about!
Get alpha channel on web, that's possible with PNG-24 images and this trick.
BE CAREFUL: that seem to work only for 10 images per page.

  # Display PNG-24 images with alpha channel on IE
  # BE CAREFUL: with this trick, only 10 PNGs seems to be supported by IE
  # Don't forget to set the size of your div
  def transpng(id, png)
    '<style type="text/css">
      <!--
        ' + id + ' {
          background-image: url(' + png + ');
        }
      -->
    </style>
    <!--[if IE]>
    <style>
      ' + id + ' {
        background-image: none;
        filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src=' + png + ', sizingMethod=\'scale\');
      }
    </style>
    <![endif]-->'
  end

to ruby rails javascript images design helpers png transparent alpha by Seb on Apr 03, 2006 1 Comments

My default layout in Rails projects

Writing a new layout from scratch gets boring, so I have a generic / default layout to use and extend from.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/ DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
	<title><%= @page_title %></title>
	<%= stylesheet_link_tag "main" %>
	<%= javascript_include_tag "prototype" %>
	<%= javascript_include_tag "scriptaculous" %>
	<%= javascript_include_tag "general" %>
	<!--[if lt IE 7.]>
	<script defer type="text/javascript" src="/javascripts/pngfix.js"></script>
	<![endif]-->
</head>

<body class="<%= @body_class %>">
	<div id="container">
			
	<%= @content_for_layout %>

	</div>
</body>
</html>

pngfix.js is available here.

to rails rubyonrails png xhtml views by peter on Feb 14, 2006 2 Comments

Get pixel colors of an image

Pys60 now has a decent Canvas and Image class.
We can draw many shapes and color them.
However, one important feature is missing, ie. getpixel().
So, you can only 'write' but not 'read' from graphics.

To get around this problem, I write a small library that
add 'getpixel' to the Image class.
Now, you can call im.getpixel(x,y) and get an (R,G,B) tuple.

# some setup
from graphics import *
im = screenshot()  # sample image

# http://larndham.net/service/pys60/getpixel.py
import getpixel
getpixel.enable(im)  # magically give Image.getpixel()
r, g, b = im.getpixel(0,0)  # top left corner
print 'Red: %s, Green:%s, Blue:%s' % (r,g,b)

Now you can do some easy image processing with getpixel.

Implementation note
===================
- This is a pure python module
- It saves an image as an uncompressed PNG file
- It reads pixel data from the file and attach it to the image.
- You need to call enable() every time you change the image.

to python image series60 png color pixel getpixel by korakot on Sep 04, 2005 1 Comments

Change OS X's default screenshot image format

At the prompt, type this:

defaults write com.apple.screencapture type image_format

Replace "image_format" with a file format name, like pdf, png, tiff, etc. Then to take screenshots, Cmd+Shift+4, then drag around the area you want to capture.

to osx images tiger screenshot screenshots png tiff by peter on Jul 08, 2005 1 Comments

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