This is simple paint, which use canvas(html5). If you wants to use this, you can dowload this and save on your server. This app have some code on jquery. But you can rewrite some lines and to do this without jquery.
Example: https://medwedd.github.io/js-paint/
You can clone this: git clone git://github.com/medwedd/js-paint.git
It has the following features:
To draw:
-brash
-line
-circle
-rectangle
-ellipse
-spray
-eraser
-text
-fill
To use:
-change color
-change line width
-change line opacity
-change text size
-change text font
-undo
-redo
-clear
-download picture on your computer
-copy rectangle are
-copy random area
-paste
For copy random area:
1.Click on copy random area.
2.Select any region.
3.Click inside area.
4.Click Paste and on random area on canvas and the image will be inserted.
Notice: if you click in button undo, when canvas contains only one drawing object, you cant to redo this object.