本质上，photo_url(:thumb) 会显示预期的缩略图 url，即使该文件实际上并不存在。
# encoding: utf-8
class WinePhotoUploader < CarrierWave::Uploader::Base
include CarrierWave::MiniMagick
storage :file
# So the :thumb will be stored in "public/assets/wines/thumb/2008-meritage-750mL.jpg" for example.
def store_dir
"assets/wines/#{version_name}"
end
def cache_dir
Rails.root.join 'tmp/uploads'
end
CarrierWave::SanitizedFile.sanitize_regexp = /[^[:word:]\.\-\+]/
# If no version name is present (original), just provide the thumb path
# This method is never called!!! Why not?
def default_url
ActionController::Base.helpers.asset_path("pages/wines/#{version_name || :thumb}/default.png")
end
# To save disk space, make sure the original image is no larger than the croppable + a few pixels
process :resize_to_fit => [2000, 2000]
version :croppable, :if => :not_cropping? do
process :common
process :resize_and_pad => [1200, 1200, :white]
process :convert => "jpg"
# Override the default naming convention...I store in folders,
# so I don't want the version prepended to the file name.
def full_filename(for_file = model.photo.file)
the_filename
end
end
version :show, :if => :not_cropping? do
process :resize_to_show
process :convert => "jpg"
def full_filename(for_file = model.photo.file)
the_filename
end
end
version :thumb, :from_version => :croppable, :if => :viewing_or_cropping? do
process :custom_thumbnail => [200, 200]
def full_filename(for_file = model.photo.file)
the_filename
end
end
def common(q=100, s='1.2x1+0.75+0.05')
manipulate! do |img|
img.combine_options do |i|
i.quality q
i.antialias
i.background :white
i.flatten
i.density 72
i.profile "#{Rails.root}/lib/color_profiles/sRGB_v4_ICC_preference_displayclass.icc"
i.strip
end
img = yield(img) if block_given?
img.combine_options do |i|
i.unsharp s
end
img
end
end
def resize_to_show
common do |img|
img.combine_options do |i|
i.trim
i.thumbnail 110
i.background :white
i.gravity :center
i.extent 170
end
img
end
end
def custom_thumbnail(width, height)
manipulate! do |img|
img.combine_options do |i|
i.distort :srt, "#{model.crop_x},#{model.crop_y} 1 -30 600,600"
i.repage.+
i.gravity :center
i.crop "#{model.crop_w}x#{model.crop_h}+0+0"
i.repage.+
i.thumbnail "#{width}x#{height}"
i.unsharp '1.2x1+0.75+0.05'
end
img
end
end
def not_cropping? picture
!model.cropping?
end
# For some stupid reason, if I only check for 'model.cropping?' and
# it returns false, the photo_url(:thumb) will always show the default_url
# and never show the actual url! This is terrible logic. The version declarations
# above should only affect the generation of thumbnails, not whether the call
# to photo_url(:thumb) works.
def viewing_or_cropping? picture
model.cropping? or model.changes.merge(model.previous_changes).empty?
end
# 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 gif png tif tiff)
end
# Only modify the version names, not the original uploaded file name
def filename
"#{ model.get_permalink(:normalized => true) }#{ File.extname original_filename }" if original_filename
end
# The filename should be the wine's permalink name (ex., 2008-merlot-reserve-750mL.jpg)
def the_filename
"#{ model.get_permalink(:normalized => true) }.jpg"
end
# Remove this when https://github.com/carrierwaveuploader/carrierwave/issues/1164 is solved.
def recreate_versions!(*versions)
if versions.any?
from_versions = versions.group_by { |v| self.class.versions[v][:options][:from_version] }
from_versions.each do |from, versions|
next if from.nil?
file = CarrierWave::SanitizedFile.new(self.versions[from.to_sym].file)
store_versions!(file, versions)
end
else
super(*versions)
end
end
end
所以调用@wine.photo_url(:thumb) 会产生
http://dev.mydomain.com/assets/wines/thumb/2006-cabernet-sauvignon-750mL.jpg
什么时候应该生产
http://dev.mydomain.com/assets/pages/wines/thumb/default.png
因为该文件不存在。