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custom shape rotation issue

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mihir_amreli
Offline
Joined: 2006-07-31
Points: 0

I am trying to rotate a custom shape around its center, but can not get the result as expected.

what i want is

*shape should be rotated around its center without moving itself.*

what my solution is currently doing is rotating
a whole shape around its center , by every rotation its changing its position.

I have multiple shapes so i have created a class to encapsulate a shape with its transform in following class

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Note: Text content in the code blocks is automatically word-wrapped

public abstract class Shoe implements Shape, ShoeShape {

// variable declaration

/**
*
*/
public Shoe() {
position = new Point();
lastPosition = new Point();
}

public void draw(Graphics2D g2, AffineTransform transform, boolean firstTime) {

AffineTransform af = firstTime ? getInitTransform()
: getCompositeTransform();

if (af != null) {

Shape s = af.createTransformedShape(this);

if (getFillColor() != null) {
g2.setColor(getFillColor());
g2.fill(s);
} else {
g2.draw(s);
}
}

}

}

public AffineTransform getCompositeTransform() {
AffineTransform af = new AffineTransform();
af.setToIdentity();
af.translate(position.getX(), position.getY());
Point2D centerP = calculateShapeCenter();
af.rotate(orientation, centerP.getX(), centerP.getY());
return af;
}

public void onMouseDrag(MouseEvent me, Rectangle2D canvasBoundary,
int selectionOperation) {

// shape operation can be either resize , rotate , translate ,
switch (selectionOperation) {
case MmgShoeViewer.SHAPE_OPERATION_MOVE:
// MOVEMENT
break;
case MmgShoeViewer.SHAPE_OPERATION_ROTATE:

Point2D origin = calculateShapeCenter();
Point2D.Double starting = new Point2D.Double(me.getX(), me.getY());
currentAngle = RotationHelper.getAngle(origin, starting);
rotationAngle = currentAngle - startingAngle;
rotate(rotationAngle);
break;
case MmgShoeViewer.SHAPE_OPERATION_RESIZE:
break;
default:
System.out.println(" invalid select operation");
}
}

public void onMousePress(MouseEvent me, Rectangle2D canvasBoundary,
int selectionOperation) {

// shape operation can be either resize , rotate , translate ,
switch (selectionOperation) {
case MmgShoeViewer.SHAPE_OPERATION_MOVE:
break;
case MmgShoeViewer.SHAPE_OPERATION_ROTATE:
Point2D origin = calculateShapeCenter();
Point2D.Double starting = new Point2D.Double(me.getX(), me.getY());
startingAngle = RotationHelper.getAngle(origin, starting);
setShapeOperation(selectionOperation);
break;
case MmgShoeViewer.SHAPE_OPERATION_RESIZE:
break;
default:
System.out.println(" invalid select operation");
}
}

public void onMouseRelease(MouseEvent me, Rectangle2D canvasBoundary,
int selectionOperation) {

// shape operation can be either resize , rotate , translate ,
switch (selectionOperation) {
case MmgShoeViewer.SHAPE_OPERATION_MOVE:
break;
case MmgShoeViewer.SHAPE_OPERATION_ROTATE:
// FIXME rotation angle computation
setShapeOperation(-1);
break;
case MmgShoeViewer.SHAPE_OPERATION_RESIZE:
break;
default:
System.out.println(" invalid select operation");
}
}

public void rotate(double angle) {
orientation = (float) angle;
}

public void translate(double deltaX, double deltaY) {

position.setLocation(deltaX, deltaY);
lastPosition.setLocation(deltaX, deltaY);
}

// another getter and setter

I am calculating angle of rotation using following method

public static double getAngle(Point2D origin, Point2D other) {

double dy = other.getY() - origin.getY();
double dx = other.getX() - origin.getX();
double angle;

if (dx == 0) {// special case
angle = dy >= 0 ? Math.PI / 2 : -Math.PI / 2;
} else {
angle = Math.atan(dy / dx);
if (dx < 0) // hemisphere correction
angle += Math.PI;
}
// all between 0 and 2PI
if (angle < 0) // between -PI/2 and 0
angle += 2 * Math.PI;
return angle;
}

in mouse press event of the canvas mouse listener

selectedShape.onMousePress(me, canvasBoundary, shoeViewer
.getShapeOperation());

i am just calling selected shape's onMousePress method

and in my mouse drag method of the canvas mouse listener , i am just calling the selected shape's onMouseDrag method which updates the rotation angle as you can see from the very first class

selectedShape.onMouseDrag(me, canvasBoundary, shoeViewer
.getShapeOperation());

and you can see the draw method of the individual shape , to draw the shape according to current transform , i am calling from paintComponent like

Iterator shoeIter = shoeShapeMap.values().iterator();

while (shoeIter.hasNext()) {

Shoe shoe = shoeIter.next();
shoe.draw(g2, firstTime);

}

where shoeShapeMap contains all of the custom shapes currently on the canvas.

is i am doing mistake in calculating angle or determining anchor point ? my current solution rotates shape 360 degree by checking all the conditions[90 degree etc.] as you can see in the above mentioned method.

i want the shape should be rotated around its center without resizing its positions ? in the word it is difficult to explain , so please suggest me any better way to show here what i want to accomplish ?

i think i have mentioned all the things related to this issue. if you have any doubts please feel free to ask me.

Thank You
Mihir Parekh