You need to build an "MS Paint"-like application in Java called JPaint.
It will have the following features:
-Pick a shape o Ellipse o Triangle o Rectangle
- Pick a primary color
- Pick a secondary color
- Click + drag to draw a shape
- Be able to change color after it's drawn
- Select shading type (outline only, filled-in, outline and filled-in)
- Select shapes
- Click and drag select shapes
- Right click to draw with secondary color (flip primary and secondary color)
- Copy
- Paste
- Delete shape
- Undo
- Redo
- Move shape
- Support keyboard shortcuts o Ctrl + C (Copy) o Ctrl + V (Paste) o Delete or backspace (Delete) o Ctrl + Z (Undo) o Ctrl + Y (Redo)
You should need to write minimal GUI code. You will need to write code for drawing shapes, which may involve some bits of UI code.
You will also need to write some handlers for click and drag events. Behavior Pick a shape.
- Selecting ellipse, rectangle, or triangle will cause a click and drag event on the canvas to draw that shape. Pick a primary color. You will need go get the primary color from the UI. Pick a secondary color.
You will need go get the secondary color from the UI. Select shading type (outline only, filled in, outline and filled in).
- Outline Only
- Only shape outline will be drawn. Use Primary Color to draw this.
- Filled-In
- Only the inside of the shape will be drawn
- there will be no visible outline. Use Primary Color to draw this.
- Outline and Filled-In
- Both the inside and the outline will be drawn. Use Primary Color for the inside and Secondary Color for the outline.
Draw Mode - Click + drag while in Draw Mode to draw a shape - click on t - Clicking and dragging moves the selected shape(s). Copy - Copies the selected shape(s) Paste - If there is anything copied, paste it on the screen somewhere. You can paste it at origin (0, 0), the middle of the canvas, or somewhere else that makes sense. Undo - Undo the last operation. Keep in mind, some operations do not need to be undo-able - for instance, "Copy" probably doesn't need to be undoable (though "paste" probably should). Redo - Redo the last operation. See undo. Delete - Deletes the selected shape(s)
1) Add a mouseHandler class that extends mouseAdapter and implements mousePressed and mouseReleased methods. Get startPoint from mousePressed and endPoint from mouseReleased.
2) add mouseHandler as a MouseListener to your PaintCanvas (paintCanvasInstance.addMouseListener()), Java will automatically call those methods and pass in the MouseEvent for you when you click and release
3) Call a run method on mouseHandler mouseReleased method that calls createShapeCommand class.
4-1) CreateShapeCommand/MoveShapeCommand/SelectShapeCommand classes uses command pattern uml design, implements ICommand interface which has a single run(Point start, Point end, ApplicationState appState) method
Like->public interface ICommand {void run(Point start, Point end, ApplicationState appState);} , it will pass along start and end pointing of the mouse and store application state in run method. Create/Select/Move are the corresponding mouseModes.
When draw is selected, createShapeCommand will have methods to create the selected shape.
When move is selected- shape is moved.
When select is selected, shape is selected(highlighted).
5) Implement strategy pattern for Triangle, Rectangle and Ellipse classes with IShapeStrategy interface. Rectangle will have all the shape properties derived from the user's currently selected shape, color choice, shadingType preference.
5-1)Add addShape(IShape shape) method from createShapeCommand and add this shape to ShapeList(this is a different class , that adds shapes passed in by addShape method).ShapeList uses collection list. Every time user selects a shape , this gets persisted in the ShapeList.
6) When addShape is called, it should notify PaintCanvas class - For this please implement Observer pattern here. PaintCanvas will be the observer and shapes getting added to the shapelist is the subject. Once addShape method adds selected shape to the shapeliest, update method will notify PaintCanvas.
6-1) Create a listener class that has a method that makes paintCanvas to call drawRect() method on Graphics2D to draw rectangle and other Graphics2D methods to draw triangle (drawTriangle()and ellipse(drawPolygon())
[[[Overall->
I have to be able to pick a shape from GUI ellipse, triangle, rectangle
Pick a primary and secondary color
Select shading type
click and drag mouse to Draw shape on the screen, be able to select the shape and move the shape]]]
Command pattern:
Implement ICommand interface and below 3 classes:
CreateShapeCommand-will be used to create a user selected shape
MoveShapeCommand-will be used to move the shape on the screen/canvas
SelectShapeCommand-will be used to select the shape on the screen
Observer pattern
Implement ISubject and Observer interface
When shape is added via addShape(Ishape shape) method to the collectionList (ShapeList), paintcanvas(is the observer) is notified.. Subject is shape getting added to shapeList, update PaintCanvas which will call listener to implement different draw methods
Static Factory
ShapeFactory
Rectangle /Triangle/Ellipse static class with shape properties.
Singleton method
The application state should persist from beginning to end so use singleton method for application state.
Overall requirement:
Pick a shape.
- Selecting ellipse, rectangle, or triangle will cause a click and drag event on the canvas to draw that shape.
Pick a primary color. You will need go get the primary color from the UI.
Pick a secondary color. You will need go get the secondary color from the UI.
Select shading type (outline only, filled in, outline and filled in).
- Outline Only - Only shape outline will be drawn. Use Primary Color to draw this.
- Filled-In - Only the inside of the shape will be drawn - there will be no visible outline. Use Primary Color to draw this.
- Outline and Filled-In - Both the inside and the outline will be drawn. Use Primary Color for the inside and Secondary Color for the outline.
Draw Mode
- Click + drag while in Draw Mode to draw a shape - click on the canvas and drag. This will draw the selected shape within those boundaries.
- Clicking and dragging moves the selected shape(s).
Copy
- Copies the selected shape(s)
Paste
- If there is anything copied, paste it on the screen somewhere. You can paste it at origin (0, 0), the middle of the canvas, or somewhere else that makes sense.
Undo
- Undo the last operation. Keep in mind, some operations do not need to be undo-able - for instance, "Copy" probably doesn't need to be undoable (though "paste" probably should).
Redo
- Redo the last operation. See undo.
Delete
- Deletes the selected shape(s)
Attachment:- src.zip