The drawing should work like a floor plan. Each line is a wall of a room. Must have its own unique id. After building all the walls, the area of the room should automatically be calculated. All data must be written to the array for further recording in Mysql. Also, when reading from Mysql, the drawing should be redrawn. Given the height data, the line should calculate the area of the wall. It should also be possible to install doors or windows on the line that automatically change the area of the wall. All this data should also be stored in an array for further processing. Line drawing should be based on the principle of autocad. Client draw lines, drawing considers length and area.
For Mysql must be array:
Room id - Line - wall id, wall name, wall area. + if have windows or doors. + additional info
After saving two or more drawings, open them on the same canvas. To get an apartment out of the rooms.