Hi Jake, "Jake B" <[EMAIL PROTECTED]> wrote on 09/21/2007 10:27:06 PM:
> Quick follow-up question to this. I believe that getScreenCTM > returns the transformation matrix mapping user coordinates to the > coordinates of the top-level viewport. No, it returns the transform to the screen coordinate system (screen pixels). > If the element is inside of a nested viewport, is there a way > to retrieve the transformation matrix to translate user > coordinates into the nested viewport coordinate system? Yes, I mentioned it below, getTransformToElement(SVGElement elem). Pass that the nested viewport element and it will give you the transform to that element's local coordinate system. I suggest you read about the SVGLocatable Interface in the SVG spec: http://www.w3.org/TR/SVG11/types.html#InterfaceSVGLocatable > Thanks again for your help. > > Jake > On 9/12/07, Jake B <[EMAIL PROTECTED]> wrote: > Works great! Thank you so much for your help! > > Jake > > On 9/12/07, [EMAIL PROTECTED] < [EMAIL PROTECTED]> wrote: > Hi Jake, > > "Jake B" <[EMAIL PROTECTED]> wrote on 09/09/2007 08:28:25 PM: > > > I was wondering, is there was a simple way to calculate the > > bounding box of an SVG element with respect to its transformations? > > The simple question here is it's bounding box in what coordinate > system? The most common requests are either the root of the SVG > tree (the root SVG elements local coordinate system), and screen pixels. > > > The getBBox method does not seem to take transformations into account. > > Correct getBBox returns the bounding box in the local coordinate > system of the element. What you need to do is take that bbox and > map it to your desired coordinate system. > > SVG provides fairly good methods for doing that. The two methods > that you might need to use are: getScreenCTM and getTransformToElement. > You can use these to get the Affine transform from the local coordinate > system of the element to the screen or any other element's local > coordinate system respectively. > > Once you have that transform you can use code like (this is js > but mapping it to Java is just adding types mostly): > var bbox = elem.getBBox(); > var mat = elem.screenCTM(); // could also be tranformToElement > var cPt = document.getRootElement().createSVGPoint(); > cPt.x = bbox.x; > cPt.y = bbox.y; > cPt = cPt.matrixTransform(mat); > // repeat for other corner points and the new bbox is > // simply the minX/minY to maxX/maxY of the four points. > > > I'm using the transform attribute because it seems to be the easiest > > and most elegant way to translate a group of elements. > > Yes, it is. > > > However, it is definitely necessary for me to get the bounding box > > of the group with respect to its transformations so that it is > > locatable within the SVG viewport. > > Right. > > > If there is not an easy way to get the bounding > > box of an element with respect to its transform, it seems like there > > are only two alternatives: to make a newer, smarter getBBox method > > that does take transforms into account, or to not use translate, > > instead recursively changing the coordinates of every member of a > > group and its children. However, neither of these seems like a very > > pretty solution, so I am somewhat stuck... > > I would greatly appreciate any guidance anyone can provide. Thanks. > > I hope the above helps. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
