JPanel paint artifacts - HELP PLEASE

Question

Hi there,
I have posted a post on this topic before, with no response, so I thought, let's try it again. I am unable to solve this problem myself and to be honest, desperate.
I am painting a greenhouse floorplan in the paintcomponent method of the JPanel. That works about 95% (roughly) of the time just fine. I can scale this floorplan and with a spinner and it will always be positioned in the middle of the JPanel.
THE PROBLEM is that every now and then during a repaint, somewhere in the middle of the paint part of the floorplan is shifted right and painted of the beginning of the JPanel. Very odd. So part of the floorplan is painted correctly on the right spot and part is shifted to the right, with a "wrap" to the nextline (see what I mean? the begin is printed halfway the page end the end is printed at the beginning).
It happens sometimes to when the application has been covered with another application, and worse sometimes it happens (but very rarely) to the entire application, so including other JPanel and controls)!
For all the scaling and positioning I use AffineTransform object (but everything when requested i cline it so no graphics object can destroy it).
Any ideas please please please?
Rene'

Answer 1

I can put in two methods because the entire file is just simply to big an complicated:
<code>
public void paintComponent(Graphics g) {
if (!this.isShowing()) {
return;
super.paintComponent(g);
// Nothing to paint if there are not sections to paint.
// Clear the background (redundant?), set the size and revalidate.
if (getSection() == null) {
g.clearRect(scrollPane.getViewport().getViewRect().x, scrollPane.getViewport().getViewRect().y, scrollPane.getViewport().getViewRect().width, scrollPane.getViewport().getViewRect().height);
this.setPreferredSize(scrollPane.getViewport().getViewRect().getSize());
EditorPanel.this.scrollPane.getViewport().revalidate();
return;
if (!validScreenDimensionInformation) {
this.recalculateScreenDimensionInformation();
if (!this.getPreferredSize().equals(new Dimension(getRequiredWidth() + borderPixels, getRequiredHeight() + borderPixels))) {
this.setPreferredSize(new Dimension(getRequiredWidth() + borderPixels, getRequiredHeight() + borderPixels));
EditorPanel.this.scrollPane.getViewport().revalidate();
Graphics2D g2d = (Graphics2D) g.create();
// Some hints for rendering.
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON));
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON));
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY));
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON));
g2d.setFont(FontCreator.createEditorPanelDisplayFont());
// The transformation required to draw the lattice girders, the path's and the lots.
// It takes into consideration the orientation and the translation. It does not take
// into account the scaling, since the object to draw have already been scaled (this
// has been done to avoid scaling of line thickness and fill patterns).
g2d.transform(getAffineTransformNoScaling());
this.latticeGirdersList.paint(g2d, BACKGROUND);
this.sectionPathList.paint(g2d, null);
this.lotsList.paint(g2d, NOTSELECTED);
this.occupiedSpaceList.paint(g2d, "");
this.latticeGirdersList.paint(g2d, CONTOUR);
this.lotsList.paint(g2d, SELECTED);
g2d.dispose();
// This method saves a lot of recalculations. Instead calculating some properties each time
// they are required, now this method is only invoked when a relevant change occurs:
// 1) section change, 2) scale change 3) panel (size) change.
public void recalculateScreenDimensionInformation() {
if (getSection() == null || scrollPane.getWidth() == 0 || scrollPane.getHeight() == 0) {
return;
double scrollPaneWidth = scrollPane.getSize().getWidth() - scrollPane.getInsets().left - scrollPane.getInsets().right - new JScrollBar(JScrollBar.VERTICAL).getMinimumSize().getWidth();
double scrollPaneHeight = scrollPane.getSize().getHeight() - scrollPane.getInsets().top - scrollPane.getInsets().bottom - new JScrollBar(JScrollBar.HORIZONTAL).getMinimumSize().getHeight();
affineTransform = new AffineTransform();
affineTransformNoScaling = new AffineTransform();
setMaxX((int) (Math.max(latticeGirdersList.getMaxX(), sectionPathList.getMaxX()) * (millimeters / getScale())));
setMaxY((int) (Math.max(latticeGirdersList.getMaxY(), sectionPathList.getMaxY()) * (millimeters / getScale())));
setMinX((int) (Math.min(latticeGirdersList.getMinX(), sectionPathList.getMinX()) * (millimeters / getScale())));
setMinY((int) (Math.min(latticeGirdersList.getMinY(), sectionPathList.getMinY()) * (millimeters / getScale())));
if (this.getSection().getOrientation().equals(Section.HORIZONTAL)) {
setTranslateX(Math.max((int) (scrollPaneHeight - Math.abs(getMaxX() - getMinX())) / 2, borderPixels) - getMinX());
setTranslateY(Math.max((int) (scrollPaneWidth - Math.abs(getMaxY() - getMinY())) / 2, borderPixels) - getMinY());
setRequiredWidth((int) getTranslateY() + getMaxY());
setRequiredHeight((int) getTranslateX() + getMaxX());
double centerX = Math.abs(getMaxX() - getMinX()) / 2 + getMinX();
double centerY = Math.abs(getMaxY() - getMinY()) / 2 + getMinY();
affineTransform.setToTranslation(centerX, centerY);
affineTransform.rotate(Math.toRadians(90));
affineTransform.translate(-centerX, -centerY);
affineTransform.translate(-centerY + centerX, centerX - centerY);
affineTransform.translate(getTranslateX(), -getTranslateY());
affineTransform.scale(millimeters / getScale(), millimeters / getScale());
affineTransformNoScaling.setToTranslation(centerX, centerY);
affineTransformNoScaling.rotate(Math.toRadians(90));
affineTransformNoScaling.translate(-centerX, -centerY);
affineTransformNoScaling.translate(-centerY + centerX, centerX - centerY);
affineTransformNoScaling.translate(getTranslateX(), -getTranslateY());
} else {
setTranslateX(Math.max((int) (scrollPaneWidth - Math.abs(getMaxX() - getMinX())) / 2, borderPixels) - getMinX());
setTranslateY(Math.max((int) (scrollPaneHeight - Math.abs(getMaxY() - getMinY())) / 2, borderPixels) - getMinY());
setRequiredWidth((int) getTranslateX() + getMaxX());
setRequiredHeight((int) getTranslateY() + getMaxY());
affineTransform.setToTranslation(getTranslateX(), getTranslateY());
affineTransform.scale(millimeters / getScale(), millimeters / getScale());
affineTransformNoScaling.setToTranslation(this.getTranslateX(), this.getTranslateY());
validScreenDimensionInformation = true;
</code.