Draw layers on image using canvas

[skavinkar]

I want to achieve following
1. Editing a image by drawing it on canvas(by drawing shape such as rectangle, circle, pencil etc)
2. To store only the drawing on canvas and not the entire canvas with image. This will be considered as single layer. User can draw as many layers on same image and save each layer separately so later he can choose the required layer and view it on canvas again.
3. As I have to store these layers somewhere, could you please help on how should I save it. Should I separate each layer separately in database or should I store coordinates for the shapes in database(this won![enter image description here][1]’t be helpful in case of pencil tool)?(need smarter approach then working harder)
4. Also user should be able to change the shape colors as per configuration(please have a look to my attached file)
5. Not finished yet. When hovered over any drawn line, the tooltip corresponding to that line should be displayed.
Please help me with proper approach to do this.

[gavinW]

GoJS is a great library for that sort of diagram.

http://www.gojs.net/

[Frinavale]

There will be a lot of JavaScript involved to do the drawing portion. I found this live demo online that may give you a starting point with this portion. If you have problems with this, you should post your questions in the JavaScript forum.

I imagine the user will use JavaScript to create Canvas objects that stack on top of your image and on top each other.

When you click the save button you will have to somehow serialize the content of the canvases and send that information to the server so that it can be stored for later use (typically people store information like this in a database).

You may need to track the objects that the user has created so that you can recreate them upon deserializing the information in the future (to be able to edit them etc).

Once you have attempted to implement this project, please post back here with the questions you have (or in the JavaScript forum if it is a JavaScript question.)

-Frinny