You mean you want a list of components that you can save and constantly re-use without clicking the mouse too much? You basically want a quick (save-able) list of components that you can drop onto the canvas quickly? Rotation of components are limited by the hardware producing your pcb's, If it does not have the ability to rotate based on *degrees then I'm pretty sure they won't implement it into the EDA, Although I'm sure this would be available in the future.

I mean the ability to place some LEDs in a line with equal distance, or place them in a circle with equal angle interval in the PCB design

There is no automated repeat placement tool in EasyEDA. It is possible to create one using the API: https://easyeda.com/Doc/Open-File-Format/ https://easyeda.com/Doc/Tutorial/API.htm#EasyEDA-API-Plug Manual rectangular placement is easy. Just set the grid to the spacing you want (or some fraction of it if your X and Y placements or at different spacings) then just place and repeat. Circular placements are more tricky because EasyEDA does not understand polar co-ordinates. What you can do is manually create an overlay in the `Document` layer of the PCB showing the desired placement of parts and use that as a guide.

in the boardview editor there is a small button at the top (kind of in the middle) which looks like 4 squares in a chequered pattern (only the squares are not black and white... they are just white). if you hover your mouse over it, it says: 'distribute array'. click that and it's pretty self  explanatory from there.

looking back actually... that button actually has 9 squares... in  a chequered pattern. the one with just 4 is 'align grid'