[SOLVED] multiuser draw question

[Tony]

I'm interested to multiuser draw app and I'd tried the example.

I found once a new client joins a room, the client can't see anything drew by others before. The client sees a blank canvas!! How to resolve it? thanks.

[colin]

hi tony,
if you want to keep a history, you'll have to add some server-side code to the example. the general approach would be:

-create a server-side room module for the drawing room
-as each client sends a drawing command, either store the command server-side or add to a server-side image that depicts the current canvas
-when a client joins, either send message(s) from the server containing the content of the canvas, or if you've been maintaining a server-side image, have the client load that image over http or in a Union message as a base64-encoded string.
-display the loaded drawing in the client

there are lots of details that will vary depending on your desired feature set, but the preceding general steps should apply to any implementation.

here's some info on coding room modules:
-java: http://www.unionplatform.com/?page_id=1072
-javascript: http://www.unionplatform.com/?page_id=2615

colin