How to Rotate with AffineTransform and keep the orignal coordinates ?

[M. othello]

Hi every Body

I'am a command pattern to rotate and translate shapes on Java Swing
The translation and the rotation work well separatly, but when I do a 60 deg. rotation and then the translation, the translation follow the new rotated coordinate.
Which means if I drag the mouse, the shape moves with 60 deg gap from the mouse mouvement vector
is there any easy solution ? please help, I'am hitting a wall here

My execute method for the rotation

public void execute() {
		System.out.println("command: rotate " + thetaDegrees );		
		Iterator iter = objects.iterator();
		Shape shape;
		while(iter.hasNext()){
			shape = (Shape)iter.next();			
			mt.addMememto(shape);			
			AffineTransform t =  shape.getAffineTransform();	
			t.rotate(Math.toRadians(thetaDegrees), shape.getCenter().x, shape.getCenter().y);
			shape.setAffineTransform(t);			
		}
	}

My execute method for the translation

public void execute() {
		Iterator iter = objects.iterator();
		Shape shape;
		while(iter.hasNext()){
			shape = (Shape)iter.next();
			mt.addMememto(shape);
			AffineTransform t = shape.getAffineTransform();
			System.out.println("Translation x :"+x + ", Translation y :"+y);
			t.translate(x,y);
			shape.setAffineTransform(t);
		}
	}

Thanks

[Campbell Ritchie]

Search my previous posts about rotation; I have had the same problem myself before now.

As far as I can remember, you might try the following:

Copy the Graphics object or the Graphics2D object. I don't think you use clone() but create() on it.

Translate it so its centre is equal to the centre of the shape you wish to rotate

Apply the affine transform by calling the Graphics2D#rotate() method.

Discard the rotated Graphics2D object.

[M. othello]

Thanks for the quick unswer
I'am gonna try that and give the feed back

[M. othello]

Hi again

Well I wanted to implemente your solution, but the architecture of the application doesn't allow it, Let me explain ...
The application use MVC, so the class shape (which is by the way a custom shape class and not the java api class) doesn't have direct access to the graphic object.
The shape change it's state and call notifyObeservers() and the view update it self...
I have no clue how to solve this issue. is there any other path I can explore

Thanks


This is the Shape Class

public abstract class Shape implements ShapeObservable{
	public static final int SELECTION_THICKNESS = 8;
	public static final int SELECTION_MARKERS_THICKNESS = 3; 
	public static final int SELECTION_ROTATION_THICKNESS = 6; 
	private boolean toBeDeleted = false;
	

	private Point center = new Point();	
	private AffineTransform t = new AffineTransform();
	
	/**
	 * Center initialized constructor.
	 * @param centerX Center's x coordinate
	 * @param centerY Center's y coordinateS
	 */	
	public Shape(double centerX, double centerY) {
		setCenter(centerX, centerY);
	}

	/**
	 * Template method pattern. draw is the template method that appropriately adjusts the transformation of the 
	 * graphics object and calls the drawHook hook method.
	 * @param g
	 */	
	final public void draw(Graphics g) {
		Graphics2D g2d = (Graphics2D)g;
		AffineTransform savedOriginalTransform = g2d.getTransform();
		g2d.transform(getAffineTransform());
		if (!isToBeDeleted())drawHook(g2d);		
		g2d.setTransform(savedOriginalTransform);		
	}
	
	
	
	
 	/**
 	 * Shape rendering method. 
 	 * @param g Graphics rendering context
 	 */
 	protected abstract void drawHook(Graphics g); 
 	public void drawSelectionMarker(Graphics g) {
		Graphics2D g2d = (Graphics2D)g;
		AffineTransform savedOriginalTransform = g2d.getTransform();
		addParentTransformation(g2d);
		g2d.transform(getAffineTransform());
		if (!isToBeDeleted())drawSelectionMarkerHook(g2d);
		g2d.setTransform(savedOriginalTransform);
 	}
 	
	/**
	 * @param g2d
	 */
	private void addParentTransformation(Graphics2D g2d) {
		if (getContainer() != null) {
			Shape container = getContainer();
			container.addParentTransformation(g2d);
			g2d.transform(container.getAffineTransform());
		}
	}

	/**
	 * Special Shape rendering method to draw the selection marker.
	 * Its default behaviour is to do nothing.
	 * @param g Graphics rendering context
	 */
	protected void drawSelectionMarkerHook(Graphics g){
		java.awt.Rectangle r = getRectangle();
		int value = 0;
		int dx = r.width/2;
		int dy = r.height/2;
		int x = r.x + dx;
		int y = r.y + dy;
		for (int i=-1; i <= 1; ++i){
			for (int j=-1; j <= 1; ++j){
				if (i == 0 && j == 0) continue;
				ShapeSelectorsMaker.drawTwoColorPoint(g, new Point(x + dx*i, y + dy*j), SELECTION_MARKERS_THICKNESS, Color.white, Color.black);
			}
		}		
		}
 
	/**
	 * Template pattern. This is the template method that will transform the point to the shape's reference space
	 * before calling the isThisPointIn hook method
	 * @param aPt specified point coordinates
	 * @return point contained inside flag value
	 */
 	final public boolean isThisPointIn(Point aPt) {
		// TODO EP We will be creating this object many times.
		Point transformedPt = new Point();
		try {
			inverseTransformPoint(aPt, transformedPt);
		} catch (NoninvertibleTransformException e) {
			e.printStackTrace();
			return false;
		}
 		return isThisPointInHook(transformedPt);
 	}

	public void inverseTransformPoint(Point ptSrc, Point ptDst) throws NoninvertibleTransformException {
		// TODO EP may be inverting the transformation many times.
		t.inverseTransform(ptSrc, ptDst);
	}
 	/**
 	 * This method is the hook method of isThisPointIn. 
 	 * @param aPt The point in the shape's reference space.
 	 * @return true if point inside the shape, false otherwise.
 	 */
 	protected abstract boolean isThisPointInHook(Point aPt);

	/**
	 * Sets the center coordinate of the rectangle.
	 * @param aCenter center coordinate of the rectangle 
	 */ 	
 	public void setCenter(Point aCenter) {
 		center.setLocation(aCenter);
		notifyObservers(); 		
 	}

	/**
	 * Sets the center coordinate of the rectangle.
	 * @param aCenter center coordinate of the rectangle 
	 */ 	
	public void setCenter(double centerX, double centerY) {
		center.setLocation(centerX, centerY);
		notifyObservers(); 		
	}
 	
	/**
	 * What is the center coordinate of the disc?
	 * @return center coordinate of the disc
	 */   	
 	public Point getCenter() {
 		return center;
	} 	
 	

	public Point getTransformedCenter() {
		Point transformed = new Point();
		t.transform(getCenter(), transformed);
		return transformed;
	}	

	
	public void setToBeDeleted(boolean toBeDeleted) {			
		this.toBeDeleted =toBeDeleted;	
		notifyObservers();
	}
	
	
	
	public boolean isToBeDeleted(){
		return toBeDeleted;		
	}
	
	/**
	 * notify all observers when a new event happens
   	 */
	public void notifyObservers(){
		Iterator iter;
	 	iter = observers.iterator();	
	 	int i = 0 ;
	 	while(iter.hasNext()){
	   		((ShapeObserver)iter.next()).update();
	   		System.out.println("i : "+i++);
	 	}
    }

	/**
	 * add a new observer
	 */
	public void addObserver(ShapeObserver aObserver){
	   observers.add(aObserver);
	}
	
	/**
	 * remove an observer from the list of the observers
	 */
	public void removeObserver(ShapeObserver aObserver){
		 observers.remove(aObserver);
	}
	
	public void setContainer(ShapeContainer sc) {
		parent = sc;
	}
	
	public ShapeContainer getContainer() {
		return parent;
	}
	
	public java.awt.Rectangle getRectangle() {
		return new java.awt.Rectangle(getCenter());
	}

	public java.awt.Rectangle getTransformedRectangle() {
		return new java.awt.Rectangle(getTransformedCenter());
	}

	public AffineTransform getAffineTransform() {
		return new AffineTransform(t);	
	}
	
	/**
	 * @param t
	 */
	public void setAffineTransform(AffineTransform newT) {		
		t = newT;
		notifyObservers();
	}

	private ShapeContainer parent;
	private List observers = new ArrayList();
}
	
	

[M. othello]

I was suggested a simplier solution, and it worked like a charme
Instead of changing the rotation methode, I should've change the translation metode in order to take account of the orientation of the shape.

This is the code for the translation:

public void execute() {
Iterator iter = objects.iterator();
Shape shape;
while(iter.hasNext()){
shape = (Shape)iter.next();
mt.addMememto(shape);
AffineTransform t = new AffineTransform();
System.out.println("Translation x :"+x + ", Translation y :"+y);
t.translate(x,y);
t.concatenate(shape.getAffineTransform());
shape.setAffineTransform(t);
}
}

Thanks guys