bounding box of a svg element

[Thomas Estier <th...@epfl.ch>]

Hello,

I'm implementing a J(DOM)tree allowing to zoom and pan (the JSVGCanvas) 
on the element selected in the tree.

Inspired by FindDialog class of Squiggle, I implemented this function as 
shown bellow. I'm not sure if it is the best way to do this.

My problem is : It doesn't take into account the successive transform of 
parent nodes. (given by <g transform="translate(100,200)"> for instance)

Do I need to parse each "transform" attribute of the parents ?
Is there a simpler way to implement this functionnality (getting the 
global bounding box of an element)?

Thanks
	Tom

[...]

if (node instanceof SVGLocatable) {
  SVGRect bb = ((SVGLocatable)node).getBBox();
  Rectangle2D shape;
  try {
   shape = new
    Rectangle2D.Double(bb.getX(),bb.getY(),bb.getWidth(),bb.getHeight());
  } catch (NullPointerException e) { return;}
  AffineTransform at;
  boolean centerZoom = false;
  if (centerZoom) {
   at = svgCanvas.getInitialTransform();
  } else {
   at = svgCanvas.getRenderingTransform();
  }
  Rectangle2D gnb = at.createTransformedShape(shape).getBounds();
  Dimension canvasSize = svgCanvas.getSize();
  AffineTransform Tx = AffineTransform.getTranslateInstance(
                         -gnb.getX()-gnb.getWidth()/2,
                         -gnb.getY()-gnb.getHeight()/2);

  if (centerZoom) {
   double sx = canvasSize.width/gnb.getWidth();
   double sy = canvasSize.height/gnb.getHeight();
   double scale = Math.min(sx,sy);
   if (scale > 1) {
    Tx.preConcatenate(AffineTransform.getScaleInstance(scale,scale));
   }
  }
  Tx.preConcatenate(AffineTransform.getTranslateInstance(
                            canvasSize.width/2,canvasSize.height/2));
					
  AffineTransform newRT = new AffineTransform(at);
  newRT.preConcatenate(Tx);
  svgCanvas.setRenderingTransform(newRT);
}
[...]
-- 
______________________________________
Thomas Estier

Field and Space Robotics

Autonomous Systems Lab
I2S-LSA
Swiss Federal Institute of Technology
1015 Lausanne EPFL
Switzerland

Tel, Fax (+41 21 693) 38 85 / 78 07
http://dmtwww.epfl.ch/isr/asl/
email: thomas.estier@epfl.ch
______________________________________
IEEE/RSJ International Conference on
Intelligent Robots and Systems

IROS 2002 : http://iros02.epfl.ch


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