有没有Paperclip翻译大师知道,当使用Paperclip保存图像时,是否可以在两个额外的字段中保存图像的尺寸(宽度和高度)?在Paperclip上传过程中如何获取这些数据?
有没有Paperclip翻译大师知道,当使用Paperclip保存图像时,是否可以在两个额外的字段中保存图像的尺寸(宽度和高度)?在Paperclip上传过程中如何获取这些数据?
仅仅是为了完整性考虑,尽管之前的回答已经提供了足够好的建议。
你可以使用Paperclip事件处理程序来代替Rails回调函数。在这种情况下,只有当图像发生变化时,大小才会被重新计算。(如果你正在使用S3存储,这可以节省相当多的时间)
has_attached_file :image, :styles => ...
after_post_process :save_image_dimensions
def save_image_dimensions
geo = Paperclip::Geometry.from_file(image.queued_for_write[:original])
self.image_width = geo.width
self.image_height = geo.height
end
图片甚至不必从S3下载(或从文件中读取),paperclip自己将其提供给事件处理程序。
有关详细信息,请参阅自述文件中的事件部分。
class Picture < ActiveRecord::Base
has_attached_file :pic, :styles => { :small => "100x100>" }, :whiny => true
after_save :save_geometry
def save_geometry
unless @geometry_saved
self.original_geometry = get_geometry(:original)
self.small_geometry = get_geometry(:small)
@geometry_saved = true
self.save
end
end
def get_geometry(style = :original)
begin
Paperclip::Geometry.from_file(pic.path(style)).to_s
end
end
end
get_geometry
函数调用ImageMagick的identify
来查找原始和调整大小后的图像的几何信息。
我将结果缓存在数据库字段中。例如,如果我上传了一个1024x768
的图像,我的缓存字段将包含:
original_geometry = "1024x768"
small_geometry = "100x75"
在Rails 4中,我使用以下Concern来保存图像尺寸:
module Dimensions
extend ActiveSupport::Concern
included do
end
module ClassMethods
def extract_dimensions_for *fields
define_method(:extract_dimensions_field_list) { fields }
before_save :extract_dimensions
fields.each do |f|
serialize (f.to_s+"_dimensions"), Hash
class_eval do
[:width, :height].each do |axis|
define_method("#{f}_#{axis}") do
return send(f.to_s+"_dimensions")[axis]
end
end
define_method("#{f}_dimensions_max") do |width, height=nil|
dims = send(f.to_s+"_dimensions")
rw = width.to_f / dims[:width]
rh = height.to_f / dims[:height] if height
r = (!height || rw < rh) ? rw : rh
return {width: (dims[:width] * r).to_i, height: (dims[:height] * r).to_i}
end
define_method("#{f}_is_portrait?") do
dims = send(f.to_s+"_dimensions")
return dims[:width] <= dims[:height]
end
define_method("#{f}_is_landscape?") do
dims = send(f.to_s+"_dimensions")
return dims[:width] > dims[:height]
end
end
end
class_eval do
def extract_dimensions
extract_dimensions_field_list.each do |f|
tempfile = send(f).queued_for_write[:original]
unless tempfile.nil?
geometry = Paperclip::Geometry.from_file(tempfile)
self.send(f.to_s+"_dimensions=", {width: geometry.width.to_i, height: geometry.height.to_i})
end
end
end
end
end
end
end
然后在你的模型中:
...
include Dimensions
extract_dimensions_for :image
...
这将把您的尺寸保存到一个序列化字段中,称为image_dimensions
,并添加一些其他方法image_width
、image_height
和image_dimensions_max(width, height)
require 'fastimage'
FastImage.size("/some/local/file.gif")
=> [266, 56] # width, height
FastImage.type("/some/local/file.gif")
=> :gif
uploaded_image = Magick::Image.read(image).first #image is what you've specified in paperclip to be your image
width = uploaded_image.columns
height = uploaded_image.rows
不确定如何使用回调使其工作。也许可以尝试以下方式:
attr_accessor :write_image_dimensions?
before_save :check_image_changed
def check_image_changed
self.write_image_dimensions? = image_changed?
end
after_save :write_image_dimensions, :if => :write_image_dimensions?
def write_image_dimensions
uploaded_image = Magick::Image.read(image).first #image is what you've specified in paperclip to be your image
self.width = uploaded_image.columns
self.height = uploaded_image.rows
save
end
paperclip-meta gem缓存所有图像样式的图像尺寸和文件大小。它在Paperclip README中被引用。paperclip-meta repo在这里:https://github.com/teeparham/paperclip-meta