SocketPainter

A Java project allowing users to draw shapes and send messages using Sockets, Threads, ObjectInputStream, ObjectOutputStream, and JPanel

How to Use

1. Run socketPainter/Hub.java to initialize the main communication hub.
2. Run socketPainter/Painter.java and enter a username when prompted to add a Painter (user) to the chatroom.
3. Begin drawing shapes and/or sending chat messages! If you want to have more than one user connected at a time, simply Run another Painter (ensuring that your IDE configurations allow for multiple instances of the same class to run in parallel)

Overview:

Hub.java

This is the main ServerSocket, it keeps track of the masterCanvas (an ArrayList of all PaintingPrimitives drawn on the shared canvas). All communication (shapes or text) is sent to/broadcasted by the Hub. Once the Hub is started, it will listen for new Painter Socket connections. When a new connection is detected, it will accept the connection, and delegate the Painter to a new PainterThread, send the masterCanvas to the new Painter, broadcast the user's arrival into the chatroom, then continue listening for new connections.

PainterThread.java

The main line of communication between the Painter and the Hub. Each PainterThread is responsible for exactly one Painter. When an update (either a chat message of type String or a newly drawn shape of type PaintingPrimitive) is received from Painter via ObjectInputStream, it determines the type of update and calls Hub.broadcastMessage or Hub.broadcastShape accordingly.

Similarly, each PainterThread also listens for chat and shape updates from the hub (PainterThread.chatUpdateFromHub and PainterThread.shapeUpdateFromHub, respectively). When an update is received, it is forwarded to its respective Painter via ObjectOutputStream.

Painter.java

Each Painter is a unique user in the studio. When a new Painter is initialized, it prompts the user for a username. If a username is entered, the Painter will try to connect to the Hub. If the connection is successful, it will initialize the canvas, and begin listening for:

1. MouseEvents to define the size/location of a shape (which is sent to the PainterThread to be forwarded along to / broadcasted by the Hub);
2. ActionEvents to change this Painter's pen color or shape;
3. Updates from the Hub (that have been forwarded by the PainterThread). These updates can be of type String (chat messages) or PaintingPrimitive (shapes). Once an update is received, the Painter determines the type, then either appends the chat to the feed or adds the shape to the paintPanel accordingly.

New Painters can see the masterCanvas upon arrival, but cannot see any of the previous chatroom messages.

Next Steps

• Currently, when a Painter disconnects, the Hub crashes. Next, I hope to implement graceful disconnect so that when a Painter leaves the studio, the Hub acknowledges its disconnect, and the other Painters can continue painting/chatting without any hiccups.
• When a user is actively drawing a shape (mouseDragged), show a preview of the shape being drawn to only that Painter - don't send shape to PainterThread until mouseReleased.