Add :write option to manipulate!. Issue #711.

[chopmo]

Options for the RMagick #write call can now be added to the options under the :write key. Since the #write call takes a block containing assignments, these options are translated to a lambda.

Also, the options argument is now yielded to the block, allowing it to be updated based on the image object (eg. change interlace option only if necessary).

Example:

manipulate! do |img, index, options|
  options[:write] = {
    :quality => 50,
    :depth => 8
  }
  img
end

is translated to

image.write do |img|
  self.quality = 50
  self.depth = 8
end

By the way I apologize for the ugly stubbing in the spec. I didn't see how else to test this without factoring out ::Magick from CW::RMagick.

[travisbot]

This pull request passes (merged 37cb9bc into 024f302).

[trevorturk]

Thanks, @chopmo! 🤘

[erichurst]

I know this is old, but a 🍻 to @chopmo. This PR made my night! Thank you.

[chopmo]

Great to hear @erichurst ! Glad you found it useful.