centerX and centerY assume you want to rotate around the center point. The point is the point you want to rotate around. If you don't specify a point, it rotates around the coordinate origin. Michael
________________________________ From: Cui Jian [mailto:[EMAIL PROTECTED] Sent: Sun 11/9/2008 5:25 AM To: batik-users@xmlgraphics.apache.org Subject: Re: [Help with Centering!!!] But the question is, why are you rotating the whole with the anchor point (centerX, centerY) in the codes: >> renderingTransform.rotate(-angle, centerX, centerY); what should this point be in this case??? I removed them and do the rotation by renderingTransform.rotate(-angle) and it seems to work too, why is that? best, Ken > Thanks Michael, it helped a lot > > Subject: RE: [Help with Centering!!!] > Date: Fri, 7 Nov 2008 11:01:43 -0500 > From: [EMAIL PROTECTED] > To: batik-users@xmlgraphics.apache.org > > In order to properly do this, you must remove/undo the rotation, > translate, then re-apply the rotation angle. > public static double getRotationAngle(AffineTransform transform) { > // Eliminate any post-translation > final AffineTransform cloned = (AffineTransform)transform.clone(); > cloned.preConcatenate(AffineTransform.getTranslateInstance( > -transform.getTranslateX(), -transform.getTranslateY())); > // Apply transformation to a vector > final Point2D firstVector = new Point2D.Double(1, 0); > final Point2D secondVector = cloned.transform(firstVector, null); > // Compute dot product > final double dotProduct = firstVector.getX() * secondVector.getX() + > firstVector.getY() * secondVector.getY(); > // Compute positive angle > double angle = Math.acos(dotProduct > / (firstVector.distance(0, 0) * secondVector.distance(0, 0))); > // Negate angle if rotation direction is clockwise > if (secondVector.getY() < 0) { > angle = -angle; > } > // Done > return angle; > } > double angle = getRotationAngle(renderingTransform); > renderingTransform.rotate(-angle, centerX, centerY); > renderingTransform.translate(offsetX, offsetY); > renderingTrasform.rotate(angle, centerX, centerY); > Michael Bishop > > *From:* ?? [mailto:[EMAIL PROTECTED] > *Sent:* Fri 11/7/2008 8:35 AM > *To:* batik-users@xmlgraphics.apache.org > *Subject:* [Help with Centering!!!] > > Dear Batik-Experts, > > I am programming an application using batik jsvgcanvas, but I've got a > big big big problem by implementing a centering function. > The sample codes are listed below, could someone please load it and > point out what's wrong??? > The codes below has a rectangle as the background and a small circle > as the to be centered object. > If the button is pressed, the cicle should be placed in the center of > the window. > It works very well if I didn't rotate (using ctrl+rightmouse) the > whole. but works quite strange if I did... > > best, > Cui > > ------------------------------------------------ > > package rotationTest; > > import java.awt.BorderLayout; > import java.awt.Dimension; > import java.awt.event.ActionEvent; > import java.awt.event.ActionListener; > import java.awt.geom.AffineTransform; > import java.awt.geom.Point2D; > > import javax.swing.JButton; > import javax.swing.JFrame; > import javax.swing.SwingUtilities; > < br>im port org.apache.batik.dom.svg.SVGDOMImplementation; > import org.apache.batik.swing.JSVGCanvas; > import org.apache.batik.util.SVGConstants; > import org.w3c.dom.DOMImplementation; > import org.w3c.dom.Document; > import org.w3c.dom.Element; > > public class RotationTest extends JFrame{ > > /** > * > */ > private static final long serialVersionUID = 1L; > > private JSVGCanvas canvas; > > private Document svgDoc; > > private static final int offset = 20; > private static final int bgWidth = 200; > private static final int bgHeight = 300; > private static final int circleX = 80; > private static final int circleY = 100; > > public RotationTest(){ > &nb sp; &n bsp; > this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); > > this.getContentPane().setLayout(new BorderLayout()); > > this.canvas = new JSVGCanvas(); > this.canvas.setDocumentState (JSVGCanvas.ALWAYS_DYNAMIC); > > DOMImplementation dom = SVGDOMImplementation.getDOMImplementation (); > svgDoc = > dom.createDocument(SVGConstants.SVG_NAMESPACE_URI, > SVGConstants.SVG_SVG_TAG, null); > > this.initBackGround(); > this.initBall() ; > > this.initCenterBtn(); > > this.canvas.setDocument(svgDoc); > > this.canvas.setMySize(new Dimension(bgWidth+2*offset, bgHeight+2*offset)); > > this.getContentPane().add(this.canvas, "Center"); > > this.pack(); > this.setVisible(true); > > } > > private void initCenterBtn() { > JButton centerBtn = new JButton("Center"); > centerBtn.addActionListener(new ActionListener( ){ > public void actionPerformed(ActionEvent arg0) { > center(); > } > }); > this.getContentPane().add(centerBtn, "North"); > } > > private void center(){ > try{ > AffineTransform at = this.canvas.getRenderingTransform(); > > Point2D circleTemp = new Point2D.Double(circleX, circleY); > > at.transform(circleTemp, circleTemp); > > double offsetX = this.canvas.getWidth()/2-circleTemp.getX(); > &nb sp; &nb sp; double offsetY = > this.canvas.getHeight()/2-circleTemp.getY(); > > at.translate(offsetX/at.getScaleX(), offsetY/at.getScaleY()); > > this.canvas.setRenderingTransform(at); > }catch(Exception e){ > e.printStackTrace(); > } > } > > private void initBackGround(){ > Element bgE = svgDoc.createElementNS(SVGConstants.SVG_NAMESPACE_URI, > SVGConstants.SVG_RECT_TAG); > svgDoc.getDocumentElement().appendChild(bgE); > bgE.setAttributeNS(null, SVGConstants.SVG_FILL_ATTRIBUTE, "lightblue "); > ; bgE.setAttributeNS(null, SVGConstants.SVG_X_ATTRIBUTE, ""+offset); > bgE.setAttributeNS(null, SVGConstants.SVG_Y_ATTRIBUTE, ""+offset); > bgE.setAttributeNS(null, SVGConstants.SVG_WIDTH_ATTRIBUTE, ""+bgWidth); > bgE.setAttributeNS(null, SVGConstants.SVG_HEIGHT_ATTRIBUTE, ""+bgHeight); > } > > private void initBall(){ > Element ballE = svgDoc.createElementNS(SVGConstants.SVG_NAMESPACE_URI, > SVGConstants.SVG_CIRCLE_TAG); > svgDoc.getDocumentElement().appendChild(ballE); > ballE.setAttributeNS(null, SVGConstants.SVG_CX_ATTRIBUTE, ""+circleX); > ballE.setAttributeNS(null, SVGConstants.SVG_CY_ATTRIBUTE, ""+ circleY); > & nbsp; ballE.setAttributeNS(null, SVGConstants.SVG_R_ATTRIBUTE, > ""+offset); > } > > public static void main(String[] args){ > SwingUtilities.invokeLater(new Runnable() { > public void run() { > new RotationTest(); > } > }); > } > > } > > <http://im.live.cn/imme/> --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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