如何通过电子邮件在Ruby中发送图形而不保存到磁盘？

Question

我正在使用Ruby脚本和“邮件”gem来发送电子邮件。

问题 - 如何在Ruby中通过电子邮件发送图形而不保存到磁盘？这可能吗？你会推荐哪种图形工具，并且“邮件”gem支持以某种方式将此流出？ （或者它是一个给定的，你必须先保存到磁盘）如果它是可能的/简单的示例代码行应该如何将是伟大的....

Answer 1

您的完整答案。

为简单起见，它使用纯Ruby PNG图形;一个真实世界的应用程序可能会使用SVG，或快速本机代码或图形API。

#!/usr/bin/env ruby 
=begin 

How to send a graph via email in Ruby without saving to disk 
Example code by Joel Parker Henderson at SixArm, joel@sixarm.com 

    http://stackoverflow.com/questions/9779565 

You need two gems: 

    gem install chunky_png 
    gem install mail 

Documentation: 

    http://rdoc.info/gems/chunky_png/frames 
    https://github.com/mikel/mail 

=end 


# Create a simple PNG image from scratch with an x-axis and y-axis. 
# We use ChunkyPNG because it's pure Ruby and easy to write results; 
# a real-world app would more likely use an SVG library or graph API. 

require 'chunky_png' 
png = ChunkyPNG::Image.new(100, 100, ChunkyPNG::Color::WHITE) 
png.line(0, 50, 100, 50, ChunkyPNG::Color::BLACK) # x-axis 
png.line(50, 0, 50, 100, ChunkyPNG::Color::BLACK) # y-axis 

# We do IO to a String in memory, rather than to a File on disk. 
# Ruby does this by using the StringIO class which akin to a stream. 
# For more on using a string as a file in Ruby, see this blog post: 
# http://macdevelopertips.com/ruby/using-a-string-as-a-file-in-ruby.html 

io = StringIO.new 
png.write(io) 
io.rewind 

# Create a mail message using the Ruby mail gem as usual. 
# We create it item by item; you may prefer to create it in a block. 

require 'mail' 
mail = Mail.new 
mail.to = 'alice@example.com' 
mail.from = 'bob@example.com' 
mail.subject = 'Hello World' 

# Attach the PNG graph, set the correct mime type, and read from the StringIO 

mail.attachments['graph.png'] = { 
    :mime_type => 'image/png', 
    :content => io.read 
} 

# Send mail as usual. We choose sendmail because it bypasses the OpenSSL error. 
mail.delivery_method :sendmail 
mail.deliver 

Answer 2

我不明白你为什么不能。在mail's documentation，你可以看到这个示例代码：

mail = Mail.new do 
    from  'me@test.lindsaar.net' 
    to  'you@test.lindsaar.net' 
    subject 'Here is the image you wanted' 
    body  File.read('body.txt') 
    add_file :filename => 'somefile.png', :content => File.read('/somefile.png') 
end 

mail.deliver! 

你必须与你在内存中的文件内容替换的:content => ...目标。这应该够了。没有必要将附件保存到磁盘中，甚至是临时保存，因为它们是用base64重新编码并添加到邮件的末尾。

对于问题的第二部分，在那里有很多plot/graph lib。例如参见this question或this lib。

这种事情并没有真正的一个以上的lib。有很多不同的用法，你必须选择适合你的需求和约束条件。