ruby-on-rails – 使用Carrierwave调整条件图像大小

对于每个上传的图像,我需要创建2个版本,并需要根据条件缩放原始图像.

下面的代码将让您更好地了解我要做的事情：

version :leftright,:if => :image?  do
  process :resize_to_fill => [667*2,778*2],:if => :is_retina_resolution?
  process :resize_to_fill => [667,778],:if => !:is_retina_resolution?
end

version :updown,:if => :image?  do
  process :resize_to_fill => [1024*2,487*2],:if => :is_retina_resolution?
  process :resize_to_fill => [1024,487],:if => !:is_retina_resolution?
end

#resize the original image
process :resize_to_fill => [1024*2,768*2],:if => :is_retina_resolution?
process :resize_to_fill => [1024,768],:if => !:is_retina_resolution?

def is_retina_resolution?(new_file)
  image = MiniMagick::Image.open(new_file.file)
  true if image[:height] >= 1536 and image[:width] >= 2048
end

显然这不起作用. Carrierwave抛出此错误：

Errno :: ENOENT – 没有这样的文件或目录 – #< ActionDispatch :: Http :: UploadedFile：0xe41d508>

我尝试了另一种变化：

version :leftright,:if => :image?  do
  if :is_retina_resolution?
    process :resize_to_fill => [667*2,778*2]
  else
    process :resize_to_fill => [667,778]
  end
end

version :updown,:if => :image?  do
  if :is_retina_resolution?
    process :resize_to_fill => [1024*2,487*2]
  else
    process :resize_to_fill => [1024,487]
  end
end

def is_retina_resolution?(new_file)
  image = MiniMagick::Image.open(new_file)
  true if image[:height] >= 1536 and image[:width] >= 2048
end

这不会引发任何错误.但它总是以视网膜大小生成图像(第一个条件)

所以我尝试了另外一个变体：

version :leftright,:if => :image? && :is_retina_resolution  do
  process :resize_to_fill => [667*2,778*2] 
end

version :leftright,:if => :image? && !:is_retina_resolution  do
  process :resize_to_fill => [667,778] 
end

version :updown,:if => :image? && :is_retina_resolution  do
  process :resize_to_fill => [1024*2,487*2]    
end

version :updown,:if => :image? && !:is_retina_resolution  do
  process :resize_to_fill => [1024,487] 
end

这不会引发任何错误,也不会创建任何版本.

有人可以帮我吗？

更新：

根据@DMKE的建议,我做了这个改动,现在它工作正常

version :leftright,:if => :is_not_retina_resolution?
end

version :updown,:if => :is_not_retina_resolution?    
end

#resize the original image
process :resize_to_fill => [1024*2,:if => :image_and_retina?
process :resize_to_fill => [1024,:if => :image_and_not_retina?
process :if => :not_image?

def image_and_retina?(img)
  is_img = image? img
  return false unless is_img
  return is_retina_resolution?(img)
end

def image_and_not_retina?(img)
  is_img = image? img
  return false unless is_img
  return !is_retina_resolution?(img)
end

# returns true if image file
def image?(new_file)
  self.file.content_type.include? 'image'
end

def not_image?(new_file)
  !self.file.content_type.include? 'image'
end

def is_retina_resolution?(new_file)
  image = MiniMagick::Image.open(self.file.file)
  true if image[:height] >= 1536 and image[:width] >= 2048
end

def is_not_retina_resolution?(new_file)
  image = MiniMagick::Image.open(self.file.file)
  true if image[:height] < 1536 and image[:width] < 2048
end