is there a way to load files from blob data?

[orlando]

like the from_blob method from Rmagick

sorry for posting this question as an issue... also, is there any google group for this gem? thanks

[jcupitt]

Hi, no, no google group, sorry. Perhaps there should be.

ruby-vips has something to make an image from a file of uncompressed binary pixel data, but that's it.

libvips has operations to wrap an image around a memory buffer, to load a PNG from a memory buffer, and to load a JPEG from a memory buffer, but they are not exposed in ruby-vips. You're right, this would be a good addition (and not much work).

I'll leave this issue open as reminder to add this.

[orlando]

cool thanks, and what about turning a VIPS::Image object to blob data, like the to_blob from RMagick, there's a data method in ruby-vips but i think that returns the RAW data from an Image.

[jcupitt]

Yes, also useful. The libvips Python interface has bother these operations so they might be a guide.

[orlando]

@jcupitt awesome, i'll take a look at that.. thanks for you'r time :)

[orlando]

btw, there's a method called to_memory in JPEGWriter and PNGWriter, that works cool to retrieve the VIPS::Image as a memory buffer, will be cool if this method is moved up to Writer and then it handles the correct to_memory method using the image headers.

[jcupitt]

This is now supported in an experimental branch, for example

jpeg_data = IO.read('/home/john/pics/wtc.jpg')
reader = JPEGReader.new(jpeg_data, :shrink_factor => 1, :fail_on_warn => true)
im = reader.read_buffer

writer = PNGWriter.new(im, :compression => 2, :interlace => false)
png_data = writer.to_memory
IO.write('out.png', png_data)

writer = JPEGWriter.new(im, :quality => 50)
jpeg_data = writer.to_memory
IO.write('out.jpg', jpeg_data)

See #38

[orlando]

👍 this is awesome.. thanks @jcupitt

[jcupitt]

Now supported in official 0.3.6.

[ryankopf]

Just want to leave a comment for anyone searching for "to_blob" for OUTPUT, you'll want something like jpegsave_buffer

[jcupitt]

The ruby-vips 2 API is:

image = Vips::Image.new_from_buffer(some_binary_data, "")
some_binary_data = image.write_to_buffer(".jpg")

Documented here:

https://www.rubydoc.info/gems/ruby-vips/Vips/Image#new_from_buffer-class_method

https://www.rubydoc.info/gems/ruby-vips/Vips/Image#write_to_buffer-instance_method

You can also load and save to arrays, C-style blocks of memory, file descriptors (including pipes), URIs, etc. etc., see:

https://www.rubydoc.info/gems/ruby-vips/Vips

For a general discussion.

[Nakilon]

Since this ticket got necroed.

is there any google group

I would ask if @jcupitt has considered enabling the new Github "Discussion" feature.

[jcupitt]

Sure, let's try it out for a bit. I've not used it before.

https://github.com/libvips/ruby-vips/discussions