By Zevan | August 3, 2018
Awhile back, I wrote some collision detection code that blitted existing interactive SVG to Canvas and then used the pixel data to figure out various aspects of the relationships between arbitrary SVG nodeTypes. A really simple trick I used can be seen in this pen:
The trick is to load the svg data into an image as a datauri. There are other tricks like this - one of which is using an svg `foreignObject` to blit html to canvas:
https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Drawing_DOM_objects_into_a_canvas
There were some browser issues at the time with this. The main one being IE 10/11 didn’t really work (tainted canvas if I recall correctly). The `foreignObject` trick didn’t work with image xlink:hrefs in safari at the time… (weirdly if you opened the dev tools it would start to work) anyway…
I ended up forking canvg for various cases. canvg is really cool… just a note, a coworker of mine went in at some point and optimized it like crazy and improved the perf a good deal by “drying things up”. Maybe I’ll suggest that he submit his optimizations at some point.
Also posted in Graphics, javascript, misc, pixel manipulation, svg | Tagged blitting, canvas, canvg, foreignObject, javascript, svg, trick |
By Zevan | August 1, 2018
This is a quick example showing how to give an input field “memory”. After you type something once and hit return it will be stored in `localStorage`. String values are ranked based on how often they are selected/entered. I know people don’t like jQuery these days, seems this pen is from a time when I still used it.
There’s definitely room for improvement here - but the key features are covered.
Usually if you want to draw lines in HTML you use canvas or SVG. Awhile back I wondered how I might do it without those. This is really just a proof of concept speed coded answer to that question:
This works by using a div with a border, rotating it and scaling it as needed so it fits between two arbitrary points.
This could be abstracted a bit more, but it works pretty well. I usually choose `setInterval` over `requestAnimationFrame` when prototyping - because I like to easily be able to change the speed of
framebased things like this. If I were to try and make this code more dynamic, I would probably switch out to `requestAnimationFrame`.
If you try and connect two lines together - you’ll notice some inaccuracy - a good argument for using SVG or canvas over something like this. That said, if you are connecting two elements using a single line, this inaccuracy would become irrelevant.
Choose two colors to breed them and create 5 new colors:
This is a speed coded pen from awhile back - the features object is interesting - it allows two objects to be bred together. In this case two colors. I could see this is as part of some advanced/abstract colorpicker that allows the user to home in on a color.