I've added a new transform tool to ChickenPaint, our Oekaki drawing tool for Google Chrome! This allows you to select an area of your canvas with the rectangular selection tool, then go to Edit->Transform to start transforming it. Grab any of the handles to stretch the selection out, click and drag in the middle of the selection to move it, or drag outside the selection in order to rotate it.
You can hold down shift while dragging a corner to scale the selection up and down without distorting it. You can hold shift while rotating to snap the rotation to the nearest 45 degrees.
If you're using Chrome or Edge, ChickenPaint will be used automatically when you go to draw. If you're not using Chrome, you can opt in to using ChickenPaint from your Oekaki settings page instead. Note that it doesn't work on Internet Explorer 9 or older, and performance is a little slow on older computers (use the old Java ChibiPaint instead in these situations, which will continue to be available).