Drag and Drop in JTree / Show line between Nodes as DropTarget

Question

Hello folks,
I am using the posted DnDTree.
My problem is to show a line between two nodes when I am drgging another node over them.
The idea is to have the posibility to sort nodes in the same level.
Has anybody an idea how to solve that?
Thanks and best reards,
Florian

Answer 1

"My problem is to show a line between two nodes when I am drgging another node over them."
Try this dragOver method:
public void dragOver(DropTargetDragEvent dtde) {
Point p = dtde.getLocation();
int closestRow = getClosestRowForLocation(p.x, p.y);
Graphics g = getGraphics();
try {
if (closestRow != -1) {
DnDNode node =(DnDNode)getPathForRow(closestRow).getLastPathComponent();
Rectangle r = getRowBounds(closestRow);
g.setXORMode(getBackground());     
if (p.y >= r.y && p.y <= r.y + r.height) {
dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
drawNewLine = false;
drawNewRectangle = false;
if (!node.getAllowsChildren() && ((r.x != x1 || r.y + r.height != y1) || rectangleDrawn)) {
drawNewLine = true;
parentNode = (DnDNode) node.getParent();
index = parentNode.getIndex(node) + 1;                    
} else if (node.getAllowsChildren()) {
if ((isCollapsed(closestRow) || (isExpanded(closestRow) && node.getChildCount() == 0)) && (rectangleDrawn || (!lineDrawn && !rectangleDrawn)) && p.y > r.y + r.height - 5) {
drawNewLine = true;
parentNode = (DnDNode) node.getParent();
index = parentNode.getIndex(node) + 1;
} else if ((lineDrawn && p.y <= r.y + r.height - 5) || ((rectangleDrawn || (!lineDrawn && !rectangleDrawn)) && (r.x != x || r.y != y))) {
drawNewRectangle = true;
parentNode = node;
index = 0;
// Marks where the drop will occur
if (drawNewLine || drawNewRectangle) {
if (lineDrawn) {
g.drawLine(x1, y1, x2, y2);
lineDrawn = false;
if (rectangleDrawn) {
g.drawRect(x, y, w, h);
rectangleDrawn = false;
if (drawNewLine) {
x1 = r.x;
y1 = r.y + r.height;
x2 = getWidth() - 5;
y2 = r.y + r.height;
g.drawLine(x1, y1, x2, y2);
lineDrawn = true;
if (drawNewRectangle) {
x = r.x;
y = r.y;
w = getWidth() - r.x - 5;
h = r.height - 1;     
g.drawRect(x, y, w, h);
rectangleDrawn = true;
} else {
dtde.rejectDrag();
index = -1;
if (lineDrawn) {
g.drawLine(x1, y1, x2, y2);
x1 = -1;
y1 = -1;
lineDrawn = false;
if (rectangleDrawn) {
g.drawRect(x, y, w, h);
x = -1;
y = -1;
rectangleDrawn = false;
} finally {
g.dispose();
Hope this works for you...
Good luck
/Tomas