CODEWITHSUNDEEP
java2dshapes
Momo
Momo

Reputation: 2491

How to scale many shapes and keep the same proportion

I have two shapes and I want to do a zoom, I use the following code

Iterator iter = objects.iterator();


    Shape shape;
    while(iter.hasNext()){
        shape = (Shape)iter.next();
        AffineTransform t = shape.getAffineTransform(); 
        int x = shape.getCenter().x;
        int y = shape.getCenter().y;            
        t.translate(-x, -y);
        t.scale(sx,sy);
        t.translate(x, y);
        shape.setAffineTransform(t);
    }

The shapes are zoomed but the distance between them became smalled Befor the zooming after the zomming

I thought making a composite shape from the two shapes and then scale it. Is there another way to keep the proportions? thanks

Upvotes: 0

Views: 1756

Answers (4)

Momo
Momo

Reputation: 2491

Thank you everybody for the answers, I found a solution that works for me

    while(iter.hasNext()){
        shape = (Shape)iter.next();                     
        AffineTransform t = new AffineTransform();
        t.scale(sx,sy); 
        t.concatenate(shape.getAffineTransform());
        shape.setAffineTransform(t); 
    }
}

Upvotes: 0

Soronthar
Soronthar

Reputation: 1601

If you want to have a true zoom, that means scaling the shapes and the white space between them. If you follow the naive route (scale each shape, and then scale the distance from a shape to every other shape) the result will not be right.

One method I'm aware of is to treat the distance between the center of two shapes as a vector of "attracting" force that have fixed direction. Then scale the magnitude of those forces and find the points that will put he system in balance again. The maths should be out there, someplace. I saw that so long ago that it seems like it was in another life.

Upvotes: 0

biziclop
biziclop

Reputation: 49804

Like I said in my comment, because you scale the shapes around their respective centers, the centers will obviously not move around. If you want everything to be scaled uniformly, don't translate anything:

  1. Find the centre point of the original viewport. This is the point you have to zoom out from.
  2. Scale everything up by (sx,sy).
  3. Translate everything by ( origcentrex*(1-sx), origcentrey*(1-sy)) to move the centre point back to the centre of the viewport.

The best way to figure these transformations out is to grab pencil and paper, draw a coordinate system and follow the transformations on paper.

Upvotes: 2

DJClayworth
DJClayworth

Reputation: 26886

The code you have zooms each shape about its centre. This means the lower lines move down, and the upper lines move up. That's why they seem to move together.

In order to not have this happen you have to zoom the shapes about a point on the lower boundary (for the upper shape) and the upper boundary (for the lower shape). Make the "y" variable the appropriate boundary.

As an alternative (and equivalent) approach translate each shape by an appropriate amount after you have zoomed it.

Upvotes: 0

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