Rotate View Tool & Apple Multitouch Trackpads
When you’re drawing or editing in Photoshop, you may need to rotate the canvas view to have a more natural drawing angle as you apply your edits.
To rotate the canvas view, press the R key to enable the Rotate View Tool. This tool will allow you to rotate the canvas by clicking-and-dragging on the canvas.
If you’re on any Apple notebook with a multitouch trackpad, you can also rotate the canvas view by using the two-finger rotate gesture.