/**
* Method to check that the current position is in the viewing area and if not scroll to center
* the current position if possible
*/
public void checkScroll() {
// get the x and y position in pixels
int xPos = (int) (colIndex * zoomFactor);
int yPos = (int) (rowIndex * zoomFactor);
// only do this if the image is larger than normal
if (zoomFactor > 1) {
// get the rectangle that defines the current view
JViewport viewport = scrollPane.getViewport();
Rectangle rect = viewport.getViewRect();
int rectMinX = (int) rect.getX();
int rectWidth = (int) rect.getWidth();
int rectMaxX = rectMinX + rectWidth - 1;
int rectMinY = (int) rect.getY();
int rectHeight = (int) rect.getHeight();
int rectMaxY = rectMinY + rectHeight - 1;
// get the maximum possible x and y index
int macolIndexX = (int) (picture.getWidth() * zoomFactor) - rectWidth - 1;
int macolIndexY = (int) (picture.getHeight() * zoomFactor) - rectHeight - 1;
// calculate how to position the current position in the middle of the viewing
// area
int viewX = xPos - (int) (rectWidth / 2);
int viewY = yPos - (int) (rectHeight / 2);
// reposition the viewX and viewY if outside allowed values
if (viewX < 0) viewX = 0;
else if (viewX > macolIndexX) viewX = macolIndexX;
if (viewY < 0) viewY = 0;
else if (viewY > macolIndexY) viewY = macolIndexY;
// move the viewport upper left point
viewport.scrollRectToVisible(new Rectangle(viewX, viewY, rectWidth, rectHeight));
}
}
