Name: dbT83986 Date: 05/01/99


specifying a Rectangle as parameter to Graphics2D.setClip()
causes virtually no performance difference compared with no
clip at all. But, the exact same Rectangle, converted into a
java.awt.geom.Area, causes a 10x performance degradation.

Curiously, the main hit is on Graphics.drawPolyline() whereas
Graphics.fillPolygon() is also affected but not nearly as much.

This performance hit forces me to use rectangular clip areas.
I would have preferred to use non-rectangular clip.
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D:\Russell\projects\test\PolygonClipProblem>java -version
java version "1.2.1"
HotSpot VM (1.0rc2, mixed mode, build E)

D:\Russell\projects\test\PolygonClipProblem>java -fullversion
java full version "JDK-1.2.1-K"
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compile and run the following app. click anywhere in the circles
to cause a redraw. Select "rectangle" to see there is little
difference in draw time. Select "area" to see a 10 times performance
degradation.

Repeat after de-selecting "fillPolygon" then repeat once more
after de-selecting "drawPolyline". The draw time for all redraws
is shown in the display. Notice that an Area clip is about 4x worse
for drawPolyline compared with fillPolygon.
--------------------------------------------------------------
public class PolygonClipProblem extends javax.swing.JFrame {
private javax.swing.JPanel _topPanel;
private javax.swing.JRadioButton _useRectangle;
private javax.swing.JRadioButton _useArea;
private javax.swing.JRadioButton _useNone;
private javax.swing.JRadioButton _doLine;
private javax.swing.JRadioButton _doFill;
private MyCanvas _canvas;

final static int CircleCount = 37;
final static int VertexCount = 200;
final static int InitialRadius = 200;
final static int RadiusChange = -5;
final static int InitialX = 205;
final static int InitialY = 205;
final static int XChange = 8;
final static int YChange = 1;
Circle _circles[];

final java.awt.Color _colors[] = {
java.awt.Color.red.darker(),
java.awt.Color.green.darker(),
java.awt.Color.blue.darker(),
java.awt.Color.yellow.darker(),
java.awt.Color.cyan.darker(),
java.awt.Color.magenta.darker()
};
int _nextColor = _colors.length;

public PolygonClipProblem() {
super("Polygon clip problem");

_topPanel = new javax.swing.JPanel();
_useRectangle = new javax.swing.JRadioButton("Rectangle");
_useArea = new javax.swing.JRadioButton("Area");
_useNone = new javax.swing.JRadioButton("No Clip");
_doLine = new javax.swing.JRadioButton("DrawPolyline");
_doFill = new javax.swing.JRadioButton("FillPolygon");
_canvas = new MyCanvas();

setSize(600,500);
addWindowListener(
new java.awt.event.WindowAdapter() {
public void windowClosing(java.awt.event.WindowEvent event) {
setVisible(false);
dispose();
System.exit(0);
}
}
);
_canvas.addMouseListener(
new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
_canvas.repaint();
}
}
);

javax.swing.ButtonGroup group = new javax.swing.ButtonGroup();
group.add(_useRectangle);
group.add(_useArea);
group.add(_useNone);

getContentPane().setLayout(new java.awt.BorderLayout());
_topPanel.setLayout(new java.awt.FlowLayout(java.awt.FlowLayout.LEFT,5,5));
_topPanel.add(_useNone);
_topPanel.add(_useRectangle);
_topPanel.add(_useArea);
javax.swing.JPanel filler = new javax.swing.JPanel();
filler.setPreferredSize(new java.awt.Dimension(100,20));
_topPanel.add(filler);
_topPanel.add(_doLine);
_topPanel.add(_doFill);
getContentPane().add(_topPanel,java.awt.BorderLayout.NORTH);
getContentPane().add(_canvas,java.awt.BorderLayout.CENTER);

createCircles();
_useNone.doClick();
_doLine.doClick();
_doFill.doClick();
}

private final void createCircles() {
_circles = new Circle[CircleCount];
for (int i = 0; i < CircleCount; i++) {
_circles[i] = new Circle(InitialX+i*XChange, InitialY+i*YChange, InitialRadius+i*RadiusChange, VertexCount);
}
}

public static void main(String args[]) {
new PolygonClipProblem().setVisible(true);
}

private final class Circle {
int _x[];
int _y[];
Circle(int x0, int y0, int radius, int count) {
_x = new int[count];
_y = new int[count];
double drad = (double)radius;
double xc = (double)x0;
double yc = (double)y0;
int count1 = count-1;
double angle = 2.0*Math.PI/(double)(count1);
for (int i = 0; i < count1; i++) {
_x[i] = (int)(xc + drad*Math.cos(angle*(double)i));
_y[i] = (int)(yc + drad*Math.sin(angle*(double)i));
}
_x[count1] = _x[0];
_y[count1] = _y[0];
}
int[] getX() { return _x; }
int[] getY() { return _y; }
}

java.awt.Color nextColor() {
_nextColor--;
if (_nextColor < 0) _nextColor = _colors.length - 1;
return _colors[_nextColor];
}

private final class MyCanvas extends javax.swing.JComponent {
java.awt.Rectangle _clipRect;
java.awt.geom.Area _clipArea;

MyCanvas() {
this.addComponentListener(
new java.awt.event.ComponentAdapter() {
public void componentResized(java.awt.event.ComponentEvent e) {
setClipGeometry();
}
}
);
setClipGeometry();
}

private final void setClipGeometry() {
_clipRect = this.getBounds();
_clipRect.setLocation(0,0);
_clipRect.grow(-50,-50);
_clipArea = new java.awt.geom.Area(_clipRect);
}
public void paintComponent(java.awt.Graphics g) {
java.awt.Graphics2D g2 = (java.awt.Graphics2D)g;

g2.setColor(this.getBackground());
g2.fillRect(0,0,this.getWidth()-1,this.getHeight()-1);
g2.draw3DRect(2,2,this.getWidth()-2,this.getHeight()-2,false);

if (_useRectangle.isSelected()) {
g2.setClip(_clipRect);
}
else if (_useArea.isSelected()) {
g2.setClip(_clipArea);
}

g2.setColor(java.awt.Color.white);
g2.fillRect(0,0,this.getWidth()-1,this.getHeight()-1);

long tm = System.currentTimeMillis();

for (int i = 0; i < CircleCount; i++) {
Circle circle = _circles[i];
if (_doFill.isSelected()) {
g2.setColor(nextColor());
g2.fillPolygon(circle.getX(), circle.getY(), circle.getX().length);
}
if (_doLine.isSelected()) {
g2.setColor(nextColor());
g2.drawPolyline(circle.getX(), circle.getY(), circle.getX().length);
}
}

tm = System.currentTimeMillis() - tm;

g2.setColor(this.getBackground());
g2.draw3DRect(2,2,this.getWidth()-2,this.getHeight()-2,false);

StringBuffer sb = new StringBuffer();
sb.append(tm);
sb.append(" ms");
g2.setColor(this.getForeground());
g2.setFont(this.getFont());
g2.drawString(sb.toString(), 55, this.getHeight() - 55);
}
}
}
(Review ID: 57717)
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