restructured code

Signed-off-by: Gerald <gera2ld@163.com>
Update README.md
only `QRCanvas` can be accessed globally

Signed-off-by: Gerald <gera2ld@163.com>
Update README.md
added liquid-like effects

Signed-off-by: Gerald <gera2ld@163.com>
Merge pull request #1 from gera2ld/dev

Dev