/** * Ensures that the specified line and offset is visible by scrolling the text area if necessary. * * @param line The line to scroll to * @param offset The offset in the line to scroll to * @return True if scrolling was actually performed, false if the line and offset was already * visible */ public boolean scrollTo(int line, int offset) { // visibleLines == 0 before the component is realized // we can't do any proper scrolling then, so we have // this hack... if (visibleLines == 0) { setFirstLine(Math.max(0, line - electricScroll)); return true; } int newFirstLine = firstLine; int newHorizontalOffset = horizontalOffset; if (line < firstLine + electricScroll) { newFirstLine = Math.max(0, line - electricScroll); } else if (line + electricScroll >= firstLine + visibleLines) { newFirstLine = (line - visibleLines) + electricScroll + 1; if (newFirstLine + visibleLines >= getLineCount()) newFirstLine = getLineCount() - visibleLines; if (newFirstLine < 0) newFirstLine = 0; } int x = _offsetToX(line, offset); int width = painter.getFontMetrics().charWidth('w'); if (x < 0) { newHorizontalOffset = Math.min(0, horizontalOffset - x + width + 5); } else if (x + width >= painter.getWidth()) { newHorizontalOffset = horizontalOffset + (painter.getWidth() - x) - width - 5; } return setOrigin(newFirstLine, newHorizontalOffset); }
protected void documentChanged(DocumentEvent evt) { DocumentEvent.ElementChange ch = evt.getChange(document.getDefaultRootElement()); int count; if (ch == null) count = 0; else count = ch.getChildrenAdded().length - ch.getChildrenRemoved().length; int line = getLineOfOffset(evt.getOffset()); if (count == 0) { painter.invalidateLine(line); } // do magic stuff else if (line < firstLine) { setFirstLine(firstLine + count); } // end of magic stuff else { painter.invalidateLineRange(line, firstLine + visibleLines); updateScrollBars(); } }