Monday, 2 September 2013

Automatically generating images for styles

Lately I have been developing a kind of SaaS website with Apex. Several companies were to be represented in this website and each company wanted to have its own logo and colors. Should be a piece of cake with CSS, shouldn’t it?

But the requirements said rounded corners for tabs and buttons, and support for IE7. That rules out HTML5 :-(.
Using plugins for rounded corners I was not able to get a stable result, so I turned to the good old sliding windows solution using background images. This way the website was stable and reliable. Below two examples of look-and-feel using the same HTML.

The only drawback of this was that a set of 12 images was needed for each company. Creating these images manually using drawing software is a time consuming, tedious and error-prone process.
So I created a webpage containing SVG-images. The webmaster could enter the colors and generate the images. Then these images could be grabbed and cut on the surrounding dotted lines in GIMP. Sounds a lot like kindergarten, doesn’t it? This was already better, but still a tedious and error-prone.

Then my 15 year old son –who is a computer programming addict like myself ;-)- came up with a solution. The open source program ImageMagick is able to convert images including SVG to PNG. The only challenge was that it runs on the command line and Apex is webbased!

The solution is to generate a Windows BAT-file that can be run on a client where ImageMagick is installed. In the BAT-file the SVG images are generated with ECHO-statements. After this ImageMagick is called to do the conversion to PNG. With this solution the neccesary images can be generated in a few minutes, just the time needed to enter the colors and to execute the BAT-file. Below is an example of the generation of the image for a button background.

echo <svg height="22px" version="1.1" width="400px" xmlns="http:www.w3.org2000svg">                  >button.svg
echo </svg>      >>button.svg

convert button.svg button.png
convert button.png -transparent white button.png

The echo statements generate the 2 lines SVG file. The first convert statement converts the SVG file to a PNG. The second convert command changes the white background to transparent in order to use the button on other than white backgrounds.

Happy Apexing! (but you can use this for any kind of website)