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From thomas.dewe...@kodak.com
Subject Re: How to use org.apache.batik.bridge.UpdateManager?
Date Tue, 27 Apr 2010 10:02:07 GMT
Hi Rishabh,

Rishabh Rao <rishabhsrao@gmail.com> wrote on 04/25/2010 03:31:43 PM:

> Also, guess what, we were able to update our canvas display without
> using UpdateManager!
> 
> Actually, in our main project, we've created a class that extends
> SwingWorker (our backend processing is a tad bit time consuming, so
> we're scheduling it on a SwingWorker thread.)
> 
> So now, we've overridden the SwingWorker.done method to our advantage!
> We're calling the JSVGCanvas object's setSVGDocument method in the
> above done method. So we can be sure that the SVGDocument is
> populated.

    This may be correct but given your earlier statements it seems
likely to be very inefficient.  The basic difference between using
the UpdateManager's update thread to modify the document and calling
'setSVGDocument' is that calling setSVGDocument causes the canvas to
start from scratch an totally rebuild the graphics tree and then
render everything from scratch.  However if you modify the document
in the UpdateManager's update thread then only the portion of the
document modified is rebuilt and rerendered.

    Based on this information the inefficiency of setSVGDocument
is basically a function of how much of the document is modified.
If you are modifying a few elements out of hundreds then calling
setSVGDocument will be very inefficient, but if you are modifying
most of those hundreds of elements then calling setSVGDocument
wouldn't be too bad.

> On 4/25/10, jonathan wood <jonathanshawwood@gmail.com> wrote:
> > Hello Rishabh, Narendra and Praveen,
> >
> > A couple of observations:
> >
> >    You really have no context in which to manipulate the DOM until the
> > document is loaded.  Your best bet is to add a GVTTreeBuilderListener.
> > Also, it is much easier to work directly with the DOM objects and let 
the
> > GVT take care of rendering the 2D.
> >   Red the attached snippet carefully...the listener code is invoked 
after
> > the document is loaded.
> >
> > private void runDemo() {
> >         svgCanvas.setDocumentState(JSVGCanvas.ALWAYS_DYNAMIC);
> >         svgCanvas.addGVTTreeBuilderListener(new 
GVTTreeBuilderAdapter() {
> >             @Override
> >             public void gvtBuildCompleted(GVTTreeBuilderEvent e) {
> >
> > svgCanvas.getUpdateManager().getUpdateRunnableQueue().invokeLater(new
> > Runnable() {
> >                     public void run() {
> >                         Element rect =
> > svgCanvas.getSVGDocument().createElementNS
> (SVGDOMImplementation.SVG_NAMESPACE_URI,
> > SVGConstants.SVG_RECT_TAG);
> >                         rect.setAttributeNS(null,
> > SVGConstants.SVG_X_ATTRIBUTE, "100");
> >                         rect.setAttributeNS(null,
> > SVGConstants.SVG_Y_ATTRIBUTE, "100");
> >                         rect.setAttributeNS(null,
> > SVGConstants.SVG_WIDTH_ATTRIBUTE, "100");
> >                         rect.setAttributeNS(null,
> > SVGConstants.SVG_HEIGHT_ATTRIBUTE, "100");
> >                         rect.setAttributeNS(null,
> > SVGConstants.SVG_FILL_ATTRIBUTE, "#2222ee");
> >
> > svgCanvas.getSVGDocument().getDocumentElement().appendChild(rect);
> >                     }
> >                 });
> >             }
> >         });
> >         Document doc =
> > SVGDOMImplementation.getDOMImplementation().createDocument
> (SVGDOMImplementation.SVG_NAMESPACE_URI,
> > "svg", null);
> >         svgCanvas.setSVGDocument((SVGDocument) doc);
> > }
> >
> >
> > On Sun, Apr 25, 2010 at 1:23 AM, Rishabh Rao <rishabhsrao@gmail.com> 
wrote:
> >
> >> Hello!
> >> We are a team 3 students who are developing an opensource application
> >> called Chart Glazer. The application helps the users draw charts 
(process
> >> diagrams, organization charts etc.) easily. It is very much similar 
to
> >> Microsoft Office 2007's SmartArt.
> >> We're using Apache Batik and Java Swing for our development. Our 
project
> >> is
> >> hosted at http://kenai.com/projects/chartglazer.
> >> The FAQ at http://xmlgraphics.apache.org/batik/faq.html talks about 
using
> >> the UpdateManager.
> >> We are facing the exact same problem, as in section 3.3 of the FAQ, 
"When
> >> I
> >> change the document in Java it only updates if I move the mouse over 
the
> >> canvas?"
> >> We have reproduced our problem into a smaller application (called
> >> SVGApplication), using NetBeans. It has a JButton (called
> >> loadDocumentJButton) and a JSVGCanvas (called myJSVGCanvas) present 
inside
> >> a
> >> JScrollPane object.
> >> Our requirement is that when we click this "loadDocumentJButton" 
button,
> >> the the "myJSVGCanvas" object must display the "myRectangle" (see 
code
> >> below.)
> >> Here is the "actionPerformed" event handler for 
"loadDocumentJButton"...
> >> private void 
loadDocumentJButtonActionPerformed(java.awt.event.ActionEvent
> >> evt)
> >> {
> >> DOMImplementation myDOMImplementation =
> >> SVGDOMImplementation.getDOMImplementation();
> >> Document myDocument =
> >> 
myDOMImplementation.createDocument(SVGDOMImplementation.SVG_NAMESPACE_URI,
> >> "svg", null);
> >> Element svgRoot = myDocument.getDocumentElement();
> >>
> >> SVGGraphics2D mySVGGraphics2D = new SVGGraphics2D(myDocument);
> >> mySVGGraphics2D.setSVGCanvasSize(new Dimension(320, 240));
> >>
> >> myJSVGCanvas.setDocumentState(JSVGCanvas.ALWAYS_DYNAMIC);
> >> myJSVGCanvas.setDocument(myDocument);
> >>
> >> Rectangle myRectangle = new Rectangle(10, 10, 60, 40);
> >>
> >> mySVGGraphics2D.draw(myRectangle);
> >>
> >> svgRoot.appendChild(mySVGGraphics2D.getRoot());
> >> }
> >> The rectangle is being displayed only when we move the mouse over the
> >> "myJSVGCanvas" object in the Swing GUI window.
> >>
> >> We understand that we must use UpdateManager to solve this problem. 
But we
> >> don't know how to use it. We searched a lot on the Internet and
> >> mail-archives, but we are not able to figure things out. We did not 
find
> >> any
> >> example programs. If we get an example program that demonstrates the 
use
> >> of
> >> UpdateManager, we will figure it out on our own. It would be great if 
you
> >> provide us with such an example program.
> >> Please help us.
> >> We are attaching the 3 files of "SVGApplication" (created 
usingNetBeans)
> >> for your reference. The above event handler function is located in 
the
> >> SVGView.java. Probably, the other two files will not be required; we 
have
> >> just attached it for completeness' sake.
> >> Thank you very much!
> >> Regards,
> >> Rishabh Rao, Narendra G S and Praveen K S
> >>
> >>
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> >>
> >
> 
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