Fix #304

[Giwayume]

• Fix width/height swap that causes #304
• Rename functions to snake case to match everything else
• Change create_new_canvas to not pass useless arguments

[Giwayume]

@viliusle This is ready for review

[viliusle]

It fixes issue. I added your changes manually (I did not like ctxOrWidth, also added legacy function names after renaming 2 functions. )

Thank you.