帶回形針的圓角

Question

如何用回形針創建圓角？我發現這個解決方案創建了rounded corners with paperclip using convert_options，但它不適用於Rails 3和Paperclip 2.4.5。生成的唯一的，如果我使用ImageMagick alpha parameter，而不是門檻放慢參數轉換命令作品：

convert example.jpg \ 
    \(+clone -alpha extract \ 
     -draw 'fill black polygon 0,0 0,15 15,0 fill white circle 15,15 15,0' \ 
     \(+clone -flip \) -compose Multiply -composite \ 
     \(+clone -flop \) -compose Multiply -composite \ 
    \) -alpha off -compose CopyOpacity -composite rounded_corners.png 

相當於

has_attached_file :avatar, 
        :styles => { :medium => ["918x483#", :png] }, 
        :convert_options => {:medium => Proc.new{self.convert_options}} 

def self.convert_options(px = 15) 
    trans = "" 
    trans << " \\(+clone -alpha extract " 
    trans << "-draw 'fill black polygon 0,0 0,#{px} #{px},0 fill white circle #{px},#{px} #{px},0' " 
    trans << "\\(+clone -flip \\) -compose Multiply -composite " 
    trans << "\\(+clone -flop \\) -compose Multiply -composite " 
    trans << "\\) +alpha off -compose CopyOpacity -composite " 
end 

該代碼段似乎產生正確的轉換命令，而是給出了一個「處理stream-xyz的縮略圖時出錯「。

Command :: convert '/tmp/stream20120109-15817-1lju7p6-0.jpg[0]' -resize "918x" 
    -crop "918x483+0+105" +repage \(+clone -alpha extract -draw 'fill black polygon 
    0,0 0,15 15,0 fill white circle 15,15 15,0' \(+clone -flip \) -compose 
    Multiply -composite \(+clone -flop \) -compose Multiply -composite \) +alpha off 
    -compose CopyOpacity -composite '/tmp/stream20120109-15817-1lju7p6-....png' 
[paperclip] An error was received while processing: #<Paperclip::PaperclipError: 
There was an error processing the thumbnail for stream20120109-15817-1lju7p6-0> 

Answer 1

最後我發現它是一個簡單的錯字。你必須使用-alpha off而不是+alpha off，那麼上面的代碼可以正常工作。有時候一個符號（ - 而不是+或者反過來）會有所不同。