Zach's Journal

AutoMotivator has a special fancy high res version so you can, in theory, make a motivational poster big enough to print and hang on your wall.

This has worked out reasonably well, but one sore point is the performance of ImageMagick for big images.

AutoMotivator works by taking the original photo, creating two PNGs for the title and inspirational text, and compositing them together against a black background with convert. On big images (2000 pixels or more on a side), it gets very slow (5-20+ seconds) and sucks up a lot of memory.

I'm not sure why it's so slow, but I suspect it's loading all the input images into memory, creating a big output image in memory, filling in the output, and then writing the output to disk.

Since my compositing needs are pretty simple, I don't have to load all that image data: producing each row of the output image only requires reading one row from each the images that single output row intersects. (This thought was originally inspired by picturetile, which must be incredibly slow.)

With that idea in mind, over the weekend I wrote a small compositing program in C. It uses the row-at-a-time input and output functions from libpng and libjpeg. The basic algorithm is:

• get the dimensions and placement of the input data sources
• note which data sources appear on each row
• create a jpeg output object, and one output row
• for each row in the output:
  • for each input source on that row:
    • merge a row from the input into the output row
  • write the output row out to disk
• finish the output jpeg

I'm really rusty at C (it's been over ten years since my last useful C program), but the end result is working well: my compositor is about ten times faster than ImageMagick at assembling big poster images. Sure, it also has a hundredth of the features, but it fortunately does exactly what I need. And the difference in user experience quality between producing a poster in two seconds and 20 seconds is huge.

When I added the caption link capability to roflbot, this is exactly how I hoped people would use it. (Results)

Check out the Spanish love!

The Thrillist bit on AutoMotivator ran today and has resulted in a nice bump in traffic. Yay!

screedbot is the latest Lisp-powered wigflip web toy. It's for making animated typewriter text graphics.

The original plan was to use a hybrid of Skippy and Vecto, but it turned out that rendering all the glyphs all the time got way too slow. To improve performance, I switched to making and caching a Skippy frame for every glyph seen in the font. That's eliminated the bottleneck of Vecto's rasterization work, and it can generate a GIF animation with hundreds of frames in a fraction of a second. I'm pretty happy with how it worked out.

It's hard to say which parts I can factor out into standalone libraries, but I do at least hope to write up the docs for the original hybrid library, Skepto, and release it.

Two script clone is still going strong. Apparently the last bidders (one guy was going to do it for $50) were incompetent lowballers. I like this comment on the current $350 bid: Sorry, but I cannot do this cheaper. It needs much work on browser and server side too.

Upside: Only 46KB! Downside: 4.13 seconds to draw, 500MB consed. But I have a few optimizations up my sleeve...

From a work-in-progress that marries Vecto and Skippy. More of a shotgun wedding at the moment. Code looks something like:

(with-animation (:width 500 :height 100)
  (looping t)
  (with-frame (:height 75 :width 15 :x 15 :y 15)
     ;; a bunch of vecto stuff
     (delay 50))
  ;;  many more with-frames
  (save-file "jack.gif"))

Fun! And I was able to do it with poor old bloated obsolete blazing-fast DSL-enabling pure rocking Common Lisp! The language with hash tables and arrays! And with a less gross incf idiom!

all function need to be same or more advance

From a work in progress. Whee!

update is what I mean.

"Can't take much credit for how realistic the motivational poster looks - awesome site here does all the work."

"Somebody cool already has it..."

When you add text in roflbot, you can now drag a little corner widget to resize it with the mouse. It's fun to watch.

There's also a special save page that'll load the completed image back into LiveJournal in addition to the other save options.

Try it out:

example: signbot

example: icanhascheezburger