/**
* Provides a way to determine the next visually represented model location at which one might
* place a caret. Some views may not be visible, they might not be in the same order found in the
* model, or they just might not allow access to some of the locations in the model.
*
* @param pos the position to convert >= 0
* @param a the allocated region in which to render
* @param direction the direction from the current position that can be thought of as the arrow
* keys typically found on a keyboard. This will be one of the following values:
* <ul>
* <li>SwingConstants.WEST
* <li>SwingConstants.EAST
* <li>SwingConstants.NORTH
* <li>SwingConstants.SOUTH
* </ul>
*
* @return the location within the model that best represents the next location visual position
* @exception BadLocationException
* @exception IllegalArgumentException if <code>direction</code> doesn't have one of the legal
* values above
*/
public int getNextVisualPositionFrom(
int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)
throws BadLocationException {
biasRet[0] = Position.Bias.Forward;
switch (direction) {
case NORTH:
case SOUTH:
{
if (pos == -1) {
pos = (direction == NORTH) ? Math.max(0, getEndOffset() - 1) : getStartOffset();
break;
}
JTextComponent target = (JTextComponent) getContainer();
Caret c = (target != null) ? target.getCaret() : null;
// YECK! Ideally, the x location from the magic caret position
// would be passed in.
Point mcp;
if (c != null) {
mcp = c.getMagicCaretPosition();
} else {
mcp = null;
}
int x;
if (mcp == null) {
Rectangle loc = target.modelToView(pos);
x = (loc == null) ? 0 : loc.x;
} else {
x = mcp.x;
}
if (direction == NORTH) {
pos = Utilities.getPositionAbove(target, pos, x);
} else {
pos = Utilities.getPositionBelow(target, pos, x);
}
}
break;
case WEST:
if (pos == -1) {
pos = Math.max(0, getEndOffset() - 1);
} else {
pos = Math.max(0, pos - 1);
}
break;
case EAST:
if (pos == -1) {
pos = getStartOffset();
} else {
pos = Math.min(pos + 1, getDocument().getLength());
}
break;
default:
throw new IllegalArgumentException("Bad direction: " + direction);
}
return pos;
}
/*
* Determine the Y offset for the current row
*/
private int getOffsetY(int rowStartOffset, FontMetrics fontMetrics) throws BadLocationException {
// Get the bounding rectangle of the row
Rectangle r = component.modelToView(rowStartOffset);
int lineHeight = fontMetrics.getHeight();
int y = r.y + r.height;
int descent = 0;
// The text needs to be positioned above the bottom of the bounding
// rectangle based on the descent of the font(s) contained on the row.
if (r.height == lineHeight) {
// default font is being used
descent = fontMetrics.getDescent();
} else {
// We need to check all the attributes for font changes
if (fonts == null) {
fonts = new HashMap<String, FontMetrics>();
}
Element root = component.getDocument().getDefaultRootElement();
int index = root.getElementIndex(rowStartOffset);
Element line = root.getElement(index);
for (int i = 0; i < line.getElementCount(); i++) {
Element child = line.getElement(i);
AttributeSet as = child.getAttributes();
String fontFamily = (String) as.getAttribute(StyleConstants.FontFamily);
Integer fontSize = (Integer) as.getAttribute(StyleConstants.FontSize);
String key = fontFamily + fontSize;
FontMetrics fm = fonts.get(key);
if (fm == null) {
Font font = new Font(fontFamily, Font.PLAIN, fontSize);
fm = component.getFontMetrics(font);
fonts.put(key, fm);
}
descent = Math.max(descent, fm.getDescent());
}
}
return y - descent;
}
/*
* A document change may affect the number of displayed lines of text.
* Therefore the lines numbers will also change.
*/
private void documentChanged() {
// View of the component has not been updated at the time
// the DocumentEvent is fired
SwingUtilities.invokeLater(
() -> {
try {
int endPos = component.getDocument().getLength();
Rectangle rect = component.modelToView(endPos);
if (rect != null && rect.y != lastHeight) {
setPreferredWidth();
repaint();
lastHeight = rect.y;
}
} catch (BadLocationException ex) {
/* nothing to do */
}
});
}