Drawing on Slides (Shallow Thoughts)

Drawing on Slides

Years ago, I saw someone demonstrating an obscure slide presentation system, and one of the tricks it had was to let you draw on slides with the mouse. So you could underline or arrow specific points, or, more important (since underlines and arrows are easily included in slides), draw something in response to an audience question.

Neat feature, but there were other reasons I didn't want to switch to that particular slide system.

Many years later, and quite happy with my home-grown htmlpreso system for HTML-based slides, I was sitting in an astronomy panel discussion listening to someone explain black holes when it occurred to me: with HTML Canvas being a fairly mature technology, how hard could it be to add drawing to my htmlpreso setup? It would just take a javascript snippet that creates a canvas on top of the existing slide, plus some basic event handling and drawing code that surely someone else has already written.

Curled up in front of the fire last night with my laptop, it only took a couple of hours to whip up a proof of concept that seems remarkably usable. I've added it to htmlpreso.

I have to confess, I've never actually felt the need to draw on a slide during a talk. But I still love knowing that it's possible. It'll be interesting to see how often I actually use it.

To play with drawing on slides, go to my HTMLPreso self-documenting slide set (with JavaScript enabled) and, on any slide, type Shift-D. Some color swatches should appear in the upper right of the slide, and now you can scribble over the tops of slides to your heart's content.