private void buildGUI() {
// add all page components to grid layout panel
pagesPanel = new JPanel();
pagesPanel.setBackground(backgroundColor);
// one column equals single page view continuous
GridLayout gridLayout = new GridLayout(0, 1, horizontalSpace, verticalSpace);
pagesPanel.setLayout(gridLayout);
// use a grid bag to center the page component panel
GridBagConstraints gbc = new GridBagConstraints();
gbc.weighty = 1.0; // allows vertical resizing
gbc.weightx = 1.0; // allows horizontal resizing
gbc.insets = // component spacer [top, left, bottom, right]
new Insets(layoutInserts, layoutInserts, layoutInserts, layoutInserts);
gbc.gridwidth = GridBagConstraints.REMAINDER; // one component per row
this.setLayout(new GridBagLayout());
this.add(pagesPanel, gbc);
// finally add all the components
// add components for every page in the document
List<AbstractPageViewComponent> pageComponents = documentViewModel.getPageComponents();
if (pageComponents != null) {
for (PageViewComponent pageViewComponent : pageComponents) {
if (pageViewComponent != null) {
pageViewComponent.setDocumentViewCallback(this);
// add component to layout
pagesPanel.add(new PageViewDecorator((AbstractPageViewComponent) pageViewComponent));
}
}
}
}
public void calculateCurrentPage() {
if (pageComponents != null) {
Rectangle viewport = scrollpane.getViewport().getViewRect();
// find visible pages
ArrayList<PageViewComponent> visiblePages = new ArrayList<PageViewComponent>(10);
Rectangle pageBounds;
int pageCount = 0;
for (AbstractPageViewComponent pageComponent : pageComponents) {
if (pageComponent != null) {
pageBounds = documentViewModel.getPageBounds(pageCount);
if (pageBounds != null && pageComponent.isShowing()) {
visiblePages.add(pageComponent);
}
}
pageCount++;
}
// find center point of view port
int x = viewport.x + (viewport.width / 2);
int y = viewport.y + (viewport.height / 2);
Point centerView = new Point(x, y);
// find out which page center is closest to center and thus the new current page
double minLength = Double.MAX_VALUE;
int minPage = -1;
double tmpDistance;
for (PageViewComponent pageComponent : visiblePages) {
if (pageComponent != null) {
pageBounds = documentViewModel.getPageBounds(pageComponent.getPageIndex());
x = pageBounds.x + (pageBounds.width / 2);
y = pageBounds.y + (pageBounds.height / 2);
// find minimum page.
tmpDistance = centerView.distance(x, y);
if (tmpDistance < minLength) {
minLength = tmpDistance;
minPage = pageComponent.getPageIndex();
}
}
}
// clean up
visiblePages.clear();
visiblePages.trimToSize();
// finally send out event to update page number
int oldCurrentPage = documentViewModel.getViewCurrentPageIndex();
documentViewModel.setViewCurrentPageIndex(minPage);
DocumentViewControllerImpl documentViewController =
(DocumentViewControllerImpl) documentView.getParentViewController();
documentViewController.firePropertyChange(
PropertyConstants.DOCUMENT_CURRENT_PAGE, oldCurrentPage, minPage);
}
}