Rain SVG


Businesses win customers when they deliver what customers want. Customers get what they want when they can customize products to their own preferences. At Rain, where I work, we recognize the profit potential that clients can achieve with this concept and have created many applications allowing users to design their own products. How do we do it? Let’s talk SVG.

Suppose we create a simple product designer containing a single rectangle. The user can rotate, scale, position, and color the rectangle. The rectangle will then be printed in spectacular fashion on the customer’s very own poster. So, Jim hops into the application and moves the rectangle to the center of the poster, doubles its size, colors it blue, then rotates it 45 degrees. He then saves his design.

How is Jim’s design saved? That is, how is Jim’s design described in such a way that (1) he can later re-open it and continue modifying his rectangle and (2) a printing shop can print his poster at virtually any size without degrading its quality?

The most common way to save an image is by using a raster format such as gif or jpg. While there are very good use cases for such formats, this is not one of them. A raster format describes an image by using a grid of pixels with each pixel carrying a color value. For example, the pixel at 1, 1 is red; the pixel at 1, 2 is green; and so on. Put all the pixels together and your eye sees an image.

Raster images don’t fulfill our requirements for a couple reasons. First, raster images have no knowledge of internal elements. It doesn’t store information about which pixels belong to a rectangle and which belong to a circle. An application may be able to analyze the pixels and make a good guess, but because the “grid of pixels” is only two-dimensional, once elements begin to overlap and become more complex even guessing turns impossible. This would greatly restrict the ability for our application to re-load a user’s work for further editing.

Second, because raster images are a grid of pixels with each pixel carrying a color value, the image cannot scale to an arbitrary size without loss of apparent quality, otherwise known as pixelation. To illustrate, imagine an image one inch wide that has 300 pixels on the first row of the pixel grid. You later decide you would like to print the image at two inches wide instead of one inch wide. The 300 pixels now must be spread across an area twice as wide as the original. While the image is made larger, no additional detail is available for the added area. The human eye begins to notice this extrapolation of data resulting in a loss of apparent quality.

So how do we store the data then? We use a vector format. Rather than storing image data in a pixel grid, vector graphics store data by using points, lines, curves, and shapes. Because the descriptors are all based on mathematics, the image can be enlarged to an infinite size without loss of quality. Likewise, a certain knowledge of the design’s individual elements is retained and can be used when loading a design for further editing. Below is a graphical comparison of vector and raster (bitmap) art:

Vector vs. Raster (bitmap)

In 1999, a group of industry leaders collaborated to make a vector specification called Scalable Vector Graphics (SVG). Although other vector formats existed previously, they each carried various restrictions or encumbrances. SVG was designed as a lightweight, open standard that could easily be used amongst a variety of applications on a variety of platforms. Design and printing applications could easily store and exchange vector design information.

While SVG is a great format for storing design data, users still need an environment where they can interact with design elements and have all the functionality of a full application. Using Flex, Rain is able to leverage both the ubiquitous Flash player browser plugin for interactivity and SVG for persistent storage. Rain has developed a library which translates what users see in the browser to a SVG file stored on the server. If users wish to continue editing their design, the SVG can be loaded back into the product designer. When the user is ready to order, the SVG document can then be shipped off to the printer.

While that might seem impressive, the real power of Rain’s SVG library comes from the complementary tools built to empower clients and their users. For starters, users can rotate, scale, crop, pan, color, add text, mask, draw, and drag-and-drop. Clients can guide users by specifying specific areas to drag-and-drop photos, enabling or disabling certain tools for individual elements or types of elements, and providing pre-built design templates.

Because the library is our own, we can tweak it as necessary. We understand that every product designer is unique and carries its own set of business rules and capabilities. We have experience implementing product designers for a wide variety of products from logos to shirts to sports trading cards to keychains. Dream away and we’ll make it happen, cap’n.

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05.28.2010 / Joris T. said:


Any chance I can play with this library?
I would like to build a drawing app for architects and export the result to svg.
The project is a Flex based app.
Thanks in advance.

05.28.2010 / Aaron Hardy said:


Thanks for the comment. The library is proprietary right now but we’re in the process of building a new and improved version that we’re considering making open source. I’ll let you know when it’s available.

05.28.2010 / Aaron Hardy said:

On the other hand, if you want to just check out some of the capabilities, you can visit http://www.studioj.com/ and play around with the app there.

08.28.2010 / AaronHardy.com :: For all your Aaron Hardy needs. » Blog Archive » DisplayObject Quirks and Tips said:

[…] having worked a great deal on the Rain SVG library, I’ve come to learn and re-learn some of the quirks and workarounds of DisplayObject, […]

10.23.2010 / AaronHardy.com » Studio J Online Scrapbooking said:

[…] the rotating, scaling, panning, colorizing, and other editing tools are provided by our in-house Rain SVG library. This to me is the most the most powerful and distinctive part of the […]

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