Good friends of stackoverflow, I am here today for guidance regarding image processing/manipulation using Ruby in a Rails environment. I'm creating on-the-fly dynamic banner ads that will feature mostly (if not completely) text. It's fairly simple with just a line or two, but I'd like the option to adjust font, text color, text size, etc.
What libraries do you recommend for this sort of task?
I've read up in rMagick a little bit and I see a lot of complaints about memory issues and lack of text rendering features. I'm not seeing many alternative active projects.
Thanks!
Edit: I got a chance to mess around with RMagick and while it's library is full featured, it seriously lacks in the text department. One feature I'm unable to use is non-breaking spaces. I'm printing a phone number in my text and it really doesn't make sense to have the area code on a different line than the rest of the number.
I'm choosing RMagick as the best solution for now, because it's full-featured and actively developed, but it is by no means a good solution.
I wrote something like the following:
require 'rubygems'
require 'RMagick'
include Magick
image = Image.new(50, 50) {
self.background_color = "white"
}
text = Draw.new
text.annotate(image, 0,0,0,40, 'Named Colors') {
self.fill = 'black'
self.pointsize = 32
}
image.write("image.png")
Which should be easy enough to follow. Also have a look at the documentation. Whilst it's not quite laid out to perfection, it's pretty much all there.
Recently I have been experimenting with creating charts/graphs from data sets using Ruby. When I was unable to find any libraries or gems that really did what I wanted, I started tinkering around with SVG graphics and I found that they are actually fairly simple to create. The SVG format is simply plain-text XML. I built an SVG image in Inkscape, saved it to a plain SVG file, and my Ruby script uses that file as a template (I dynamically update a few line elements and several text labels and leave the structure of the file intact). SVG gives you all sorts of font options (like CSS or HTML).
These two tutorials give you a quick look at SVG and how you can build an image fairly quickly with any app or language that can write to a text file. Ruby can use plain old puts to build a SVG file, or you can let the 'builder' gem do the formatting for you.
You can farm out your image processing needs to the command-line version of ImageMagick instead of using the the rMagick Ruby bindings.
Are you limited to MRI Ruby? If there's any way you can get access to a jRuby instance (maybe on an EC2 stack for instance) you could make use of the wonderful Processing library. A project I worked on before did something similar with Processing via jRuby, it's really quite a potent combination.
You can use mini-magick to work with ImageMagick in Ruby.
The ImageScience library is made for people who hate rMagick's poor memory usage, etc. I use it as a backend processor for the attachment_fu plugin, which makes it easy to make an image model in Rails.
It may be worth having a look at the image_processing gem:
https://github.com/janko/image_processing
It makes use of either ImageMagick or VIPS (the latter being even more efficient).
Related
I have a slider which shows some custom made images on the main site.
At the moment every time I want to change something I need to deploy a new image with the changed text.
I was wondering if there is a gem which can be settled up to put some custom text over a default image if several conditions are met.
To do any kind of programatic image manipulation I would look at imagemagick. Think of photoshop in an open source binary. As imagemagick has been written in C you will not be able to call it directly. Instead use rmagick. Rmagick provides a nice ruby interface around imagemagick's c based API. There might be an updated way to do this as I have not worked with images in ruby for years however it's the best place to start. GL.
I'm aware of pdf-stamper, but I'm trying to avoid switching everything to jruby right now.
I just need to "stamp" an image that I generate within the rails app (a PDF417 barcode) into a form field in the PDF document (there's an FDF; it's a document template kinda thing).
I'm filling out the text-based fields by just shelling out to pdftk, so if there's a way to do it using pdftk, I'd be fine with that, but I've looked high and low for one without any luck.
How about using a barcode font? some alternatives too. I haven't used that one but there may be others available too
I know I'm late to the party, but the PDF417 Rubygem should do what you need. https://rubygems.org/gems/pdf417 will generate it and if you have chunky_png installed you can easily write out PNGs to a file.
I'm creating a Facebook app using Rails and hosted on Heroku and I'm having a bit of trouble finding the ideal way to solve a problem. I want the user to be able to move their photos around on the screen, position them, and then download that as either a PDF or a PNG file to be emailed or printed. I have the app getting the user's facebook photos and they can drag them on to a HTML5 Canvas element to position them. Taking this canvas, however, and converting it into something printable is where I'm hitting a dead end.
Basically I have a few ideas I have tried:
Convert the Canvas to a PNG using toDataURL() - Would work perfectly but since the photos are external, the canvas is "dirty" and will throw up a security issue. I've thought about trying to copy the pixels of each image to a pixel array but I've heard this may not work either due to security issues. Since the app is dealing with people's facebook images I really don't want to store them on the app's server.
Use PDFKit/wkhtmltopdf to create a PDF using Rails - I've tried this, but since the app is a Sinatra app (I think), it's confusing me a lot. It's throwing errors with the to_pdf call saying 'Command Failed'. I've tried adding a config.middleware.use line but I'm not 100% sure where to put it and everywhere seems to be failing saying "config" is an undefined variable. Also installing wkhtmltopdf seems to fail on Heroku once I test it outside localhost.
Use Prawn to create a PDF using Rails - I've tried prawn but it seems to have a similar problem to PDFKit and I get confused about what goes where on a Sinatra app. I'm sure I read as well that people were having problems with it too.
Have I missed any obvious solutions to this, or is there something I'm not thinking of? All I want to do is create some kind of easily printable file with positioning intact that can be easily downloaded and printed by the user but I've come across so many problems that I don't know where to go next and I'm going round in circles.
If anyone had any advice for me about how I could get around this problem I'd really appreciate it.
if prawn is giving you grief just use one of the jquery plugins to print your div content. You could even configure a pdf printer and print the document instead of hard copy if you so wish/need images in pdf format.
I use http://archive.plugins.jquery.com/project/jqPrint plugin in one of my projects and it works like a charm.
It sounds like many of your issues relate to the necessary PDF binaries not being accessible on Heroku. In following with the twelve factor approach to dependency isolation Heroku purposely provides a very bare system.
If you need to run a custom binary on Heroku I'd suggest looking at a tool called Vulcan which can compile a binary that's compatible with the Heroku runtime.
After several Google searches, it appears that the way to create PDFs in Rails from HTML and CSS (versus a new markup language) is to use Prince.
With licensing at $3800 for my non-big-commercial app, I'm wondering if this is, in fact, consensus or people have an alternative they can share the whats and hows.
You may check out prawn too. Tutorial can be found on railscasts.com.
This may fit the bill: http://code.google.com/p/wkhtmltopdf/
We tried tow solutions:
using latex generate pdf, there is ruby gem code rtex
using java library iText, use it you may need rjb which allow you using java lib directly in ruby code, just like jruby, but you don't need build all you application on jruby.
I create tons of different PDF files on the fly from various data sources using Rails, including finest layout. I create need to create them for presenting products to customers.
After having tried all the tools mentioned above, Prince is the best tool for this task.
Prince's rendering quality & CSS support (better than some browsers) is its main selling point. If you're only generating documents with simple layouts, stick with Prawn.
I've got some experience using haml (+sass) on rails projects. I recently started using them with blueprintcss - the only thing I did was transform blueprint.css into a sass file, and started coding from there. I even have a rails generator that includes all this by default.
It seems that Compass does what I do, and other things. I'm trying to understand what those other things are - but the documentation/tutorials weren't very clear.
These are my conclusions:
Compass comes with built-in sass mixins that implement common CSS idioms, such as links with icons or horizontal lists. My solution doesn't provide anything like that. (1 point for Compass).
Compass has several command-line options: you can create a rails project, but you can also "install" it on an existing rails project. A rails generator could be personalized to do the same thing, I guess. (Tie).
Compass has two modes of working with blueprint: "basic" and "semantic" usage. I'm not clear about the differences between those. With my rails generator I only have one mode, but it seems enough. (Tie)
Apparently, Compass is prepared to use other frameworks, besides blueprint (e.g. YUI). I could not find much documentation about this, and I'm not interested on it anyway - blueprint is ok for me (Tie).
Compass' learning curve seems a bit stiff and the documentation seems sparse. Learning could be a bit difficult. On the other hand, I know the ins and outs of my own system and can use it right away. (1 point for my system).
With this analysis, I'm hesitant to give Compass a try.
Is my analysis correct? Are Am I missing any key points, or have I evaluated any of these points wrongly?
The ideal goal is separation of style and content: it's not always possible 100%, but it can be done reasonably well by using semantic markup. Blueprint and other CSS frameworks utterly fail at this.
The original idea behind Compass was to avoid polluting HTML with the visual markup that Blueprint generates: if you're writing class="column-4" in your markup, then you might as well put style="width:160px" in there instead. Semantically it's the same meaning, and the same amount of repetition to maintain.
Compass turns a Blueprint class like .column-4 into a mixin which you can apply to a meaningful selector:
#sidebar
+column(4)
This way, you only need to maintain it in the stylesheet, not across a number of templates and HTML files.
Compass is project-aware. It will handle compiling your whole tree of stylesheets, even automatically on save when you run compass watch.
There are some very helpful functions provided by compass, for example:
image_url is a configurable function that can handle relative or absolute paths or even set up rotating asset hosts if you need to.
The CSS3 module takes care of all the browser-specific style rules for rounded corners, shadows, etc.
General utilities provide helpers for the stuff you do all the time, but with less repetition (especially for the cross-browser issues). These are some basic ones I use a lot:
+clearfix and +pie-clearfix (cross-browser clearing methods)
+float ensures you don't forget display:inline in front of it for IE... (if the time comes to drop the old IEs, it's one single change.)
+replace-text hides text and positions an image replacement background.
+hover-link adds the :hover underline rule to a base link style
You can check these out on the new docs site for Compass.
Then, Compass provides the facilities for a number of other style frameworks in addition to the built-in Blueprint. Do check out Susy for example, which is a Sass-native layout framework, not just a CSS port. It specializes in flexible and fluid grids.
'Semantic mode' refers to the possibility to use more semantic class names than the ones css frameworks ship with: .article vs .grid_1. which i personally think is a big +.
I'm not sure if these resources have only shown up recently, but have you seen the Compass CSS3 helpers and the General utilities - (both well documented in my opinion) - they've really sped up my interface builds a great deal.
Another great resource is the Compass plugins page.
Personally I like to copy these utility Sass files out the rubygem and manually include them in my project's Sass files as it feels pretty weird referencing Sass which is stored out of the project.
Compass looked like a great solution for me as well, but after trying it on a project I didn't really see the great advantage of using it for me. Like you, I'm just fine with blueprint, and I didn't see the need to add yet another layer on top of haml/sass.
I eventually stripped the compass from that project and just go with a sass version of the blueprint CSS files, and go from there. I store any custom/additional styles in a separate sass file and that's it. No need for compass or anything like that if you just want to keep it simple.