From: Ezra Zygmuntowicz <ezra@...>
Date: 2005-06-28T06:35:47+09:00
Subject: Re: What do you want to see in a Sparklines Library?

I cannot access your server either. I have tried both times you  
posted it and it would just time out multiple times.
-Ezra
On Jun 27, 2005, at 1:24 PM, Daniel Nugent wrote:

> I'm doing that right now actually, I just want to add the ability to
> do data: URIs, which should be pretty easy I think.
>
> It's strange that you can't access my server Adam, is anyone else
> having that problem?
>
> On 6/27/05, Carl Youngblood <carl.youngblood@gmail.com> wrote:
>
>> One thing that would make sparklines a lot more universally  
>> accessible to
>> all browsers would be to get rid of the dependency on data urls.  
>> The basic
>> idea is to return the proper MIME type to the browser and then  
>> just start
>> spitting out the raw binary data of the PNG.
>>
>> Here is an example:
>>
>> #!/usr/bin/ruby
>>
>> require 'base64'
>> require 'cgi'
>> require 'zlib'
>>
>> def build_png_chunk(type,data)
>> to_check = type + data
>> return [data.length].pack("N") + to_check +
>> [Zlib.crc32(to_check)].pack("N")
>> end
>>
>> def build_png(image_rows)
>> header = [137, 80, 78, 71, 13, 10, 26, 10].pack("C*")
>> raw_data = image_rows.map { |row| [0] + row }.flatten.pack("C*")
>> ihdr_data = [image_rows.first.length,
>> image_rows.length,
>> 8,2,0,0,0].pack("NNCCCCC")
>> ihdr = build_png_chunk("IHDR", ihdr_data)
>> idat = build_png_chunk("IDAT", Zlib::Deflate.deflate(raw_data))
>> iend = build_png_chunk("IEND", "")
>>
>> return header + ihdr + idat + iend
>> end
>>
>> def bumpspark(results)
>> white, red, grey = [0xFF,0xFF,0xFF], [0,0,0xFF], [0x99,0x99,0x99]
>> rows = results.inject([]) do |ary, r|
>> ary << [white]*15 << [white]*15
>> ary.last[r/9,4] = [(r > 50 and red or grey)]*4
>> ary
>> end.transpose
>> return build_png(rows)
>> end
>>
>> def send_to_browser(results)
>> puts "Content-type: image/png"
>> puts "Expires: Wed, 11 Nov 1998 11:11:11 GMT"
>> puts "Cache-Control: no-cache"
>> puts "Cache-Control: must-revalidate"
>> puts
>> print bumpspark(results)
>> end
>>
>> send_to_browser (0..22).map { rand 100 }
>>
>>
>> See this in action at the following URL:
>>
>> http://youngbloods.org/sparkline.cgi
>>
>> Carl
>>
>>
>>
>
>
> -- 
> -Dan Nugent
>
>

-Ezra Zygmuntowicz
Yakima Herald-Republic
WebMaster
509-577-7732
ezra@yakima-herald.com