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From "Auzinger, Thomas" <TAuzin...@ert.com>
Subject Newbie problem with batik speed
Date Fri, 13 Apr 2007 19:40:46 GMT
I'm new to Batik and used it for a prototype that displays waveforms and
measurements.  I'd like to learn some "best practices" for Batik. It works
o.k., except for the following:

1.	I wanted to have a  big crosshair instead of the default cursor, so
I defined one in the static SVG document that I put all my data in.:
<g id="cursor" transform="translate(0,0)">
	<line stroke-width=".1" style="fill:none;stroke:red" y1="-10"
y2="10" x1="0" x2="0"/>
	<line stroke-width=".1" style="fill:none;stroke:red" x1="-10"
x2="10" y1="0" y2="0"/>
</g>

In my mousemotionlistener I change the translate(*,*) to whatever it needs
to be.  This works, but it is kind of sluggish, and the SVG cursor is always
somewhat behind the system cursor:
    public void moveCursor(MouseEvent e) {
        try {
            AffineTransform at = this.jsvgCanvas.getViewBoxTransform()
                                                .createInverse();
            Point2D p = new Point2D.Double(e.getX(), e.getY());
            p = at.transform(p, null);

            if (EcgApplet.cursorTransform == null) {
                Element cursor = this.jsvgCanvas.getSVGDocument()
                                                .getElementById("cursor");
                EcgApplet.cursorTransform =
cursor.getAttributeNode("transform");
            }

            EcgApplet.cursorTransform.setValue("translate(" + p.getX() + ","
                                               + p.getY() + ")");
        }
        catch (Exception ex) {
            ex.printStackTrace();
            System.out.println(ex);
        }
    }
(If the design looks bad it's because it is, this prototype will be thrown
away)

2.	Displaying the measurements (i.e. drawing about 84 lines and 24
texts) takes about 2-3 seconds on a 3GHz dual core machine.
The method below is called 12 times:

    public void displayItem(GlobalAnalysisItem ai, int beat, int height) {
        long t0 = System.currentTimeMillis();
        String svgNS = SVGDOMImplementation.SVG_NAMESPACE_URI;
        SVGDocument doc = jsvgCanvas.getSVGDocument();
        int lArrow = 3;
        int x1 = ai.getOnSet().intValue() / 2;
        int x2 = ai.getOffSet().intValue() / 2;
        int yBase = 100;
        int yTop = -200;
        int yLine = -height;
        int yName = yLine - 2;
        int yValue = yLine + 5;
        String name = AnalysisItem.displayType(ai.getTypeID());
        String value = ai.getValue().intValue() + "";

        Element dimensioning1 = doc.getElementById("dimensioning");
        Element dimensioning = jsvgCanvas.getSVGDocument()
                                         .createElementNS(svgNS, "g");

        // calipers
        long t0a0 = System.currentTimeMillis();
        dimensioning.appendChild(createLine(x1, yBase, x1, yTop));

        long t0a = System.currentTimeMillis();
        System.err.println("displayItemA:" + (t0a - t0a0));
        dimensioning.appendChild(createLine(x2, yBase, x2, yTop));

        // line
        dimensioning.appendChild(createLine(x1, yLine, x2, yLine));

        // left arrow
        dimensioning.appendChild(createLine(x1, yLine, x1 + lArrow,
                                            yLine + (lArrow / 2)));
        dimensioning.appendChild(createLine(x1, yLine, x1 + lArrow,
                                            yLine - (lArrow / 2)));

        // right arrow
        dimensioning.appendChild(createLine(x2, yLine, x2 - lArrow,
                                            yLine + (lArrow / 2)));
        dimensioning.appendChild(createLine(x2, yLine, x2 - lArrow,
                                            yLine - (lArrow / 2)));

        // name
        dimensioning.appendChild(createText((x1 + x2) / 2, yName, name));

        // value
        dimensioning.appendChild(createText((x1 + x2) / 2, yValue, value));

        dimensioning1.appendChild(dimensioning);

        long t1 = System.currentTimeMillis();
        System.err.println("displayItem:" + (t1 - t0));
    }

Is there anything blatantly wrong with what I'm doing?  What can I do
better?

Thanks,

Thomas

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