Ruby on Rails下的图像处理入门教程

sudo apt-get -y install imagemagick
sudo apt-get -y install libmagic-dev
sudo apt-get -y install libmagickwand-dev

brew install imagemagick

# Gemfile
 
gem 'mini_magick'

# Open an image from a website
 
image = MiniMagick::Image.open("https://s3.amazonaws.com/StartupStockPhotos/20140808_StartupStockPhotos/85.jpg")
 
# Get the Image's width
image.width # 4928
 
# Get the image's height
image.height #3264

image.resize "2048x1536"
 
# Now get the image's new width and height
 
p "Width is => #{image.width} and height is => #{image.height}"

image.path # temp path

image.write "public/uploads/test.jpg"

image.format "png"
image.write "public/uploads/test.png"

image.combine_options do |i|
 i.resize "2048x1536"
 i.flip
 i.rotate "-45"
 i.blur "0x15"
end
image.write "public/uploads/blur.png"
 
![Some weird result](blur.png)

# Gemfile
 
gem 'carrierwave'
gem 'carrierwave-mongoid', :require => 'carrierwave/mongoid'

bundle install

#app/uploaders/image_uploader.rb
 
class ImageUploader < CarrierWave::Uploader::Base
 # Include RMagick or MiniMagick support:
 include CarrierWave::MiniMagick
 
 # Choose what kind of storage to use for this Uploader:
 storage :file
 # Override the directory where uploaded files will be stored.
 # This is a sensible default for uploaders that are meant to be mounted:
 def store_dir
  "uploads/images"
 end
end

# app/uploaders/image_uploader.rb
...
# Add a white list of extensions which are allowed to be uploaded.
# For images you might use something like this:
def extension_white_list
 %w(jpg jpeg png gif)
end
...

# app/models/image.rb
 
class Image
 include Mongoid::Document
 include Mongoid::Timestamps
 include Mongoid::Paranoia
 include Mongoid::Attributes::Dynamic
 include Rails.application.routes.url_helpers
 
 mount_uploader :media, ImageUploader, mount_on: :media_filename
end

# app/uploaders/image_uploader.rb
 
#.....
process :resize_to_fill => [200, 200]
process :convert => 'png'
#.....

media = File.open("/Users/test/Desktop/image/jpg")
img = Image.new(:media => media)
img.save

# app/uploaders/image_uploader.rb
 
#.....
version :thumb do
 process :resize_to_fit => [100, 100]
 process :convert => 'jpg'
end
 
version :cover  do
 process :resize_to_fit => [240, 180]
 process :convert => 'jpg'
end
 
#.....

img.media.versions[:thumb] # returns the thumb image instance
img.media.versions[:cover] # returns the cover image instance

# app/uploaders/image_uploader/rb
 
#....
version :cover, :if => :is_live? do
 process :resize_to_fit => [240, 180]
 process :convert => 'jpg'
end
 
def is_live?(img = nil)
 @is_live
end
 
def is_live=(value)
 @is_live = value
end
#....

img.media.is_live = true
img.save
img.media.recreate_versions! :cover

# lib/resque/image_queue.rb
class ImageQueue
 @queue = :image_queue
 def self.perform(image_id)
  image = Image.find image_id
  img.media.is_live= true
  img.save
  img.media.recreate_versions! :cover
 end
end

Resque.enqueue(ImageQueue, img.id.to_s)

gem 'carrierwave-imageoptimizer'

# app/uploaders/image_uploader.rd
 
#.....
 
include CarrierWave::ImageOptimizer
process :optimize
process :quality => 100
#....