JavaFX GridPane 设置列/行后节点边界不正确

Question

When setting new row and column positions of a node contained in a GridPane, the bounds do not update until sometime later (My guess is that JavaFX calculates these at the end of the loop). I was wondering if there was a way to force these bounds to be re-calculated so that boundsAfter contains the correct values rather than the same as boundsPre (as shown in the output)?.

Bounds boundsPre = theNode.localToScene(theNode.getBoundsInLocal());
System.out.println("PRE-MOVE: " + boundsPre);

GridPane.setColumnIndex(theNode, newCol);
GridPane.setRowIndex(theNode, newRow);
// Todo: Force JavaFX to recalculate the bounds here

Bounds boundsAfter = theNode.localToScene(theNode.getBoundsInLocal());
System.out.println("BOUNDS: " + boundsAfter );

Output:

PRE-MOVE: BoundingBox [minX:25.0, minY:339.0, minZ:0.0, width:243.0, height:116.0, depth:0.0, maxX:268.0, maxY:455.0, maxZ:0.0]
BOUNDS: BoundingBox [minX:25.0, minY:339.0, minZ:0.0, width:243.0, height:116.0, depth:0.0, maxX:268.0, maxY:455.0, maxZ:0.0]

Answer 1

Solution 1

Call the layout() method on the base pane after setting the row or column position. This " Executes a top-down layout pass on the scene graph under this parent " according to the Oracle JavaFX Documentation, which results in the bounds to be re-calculated of all child nodes belonging to the pane.

Bounds boundsPre = theNode.localToScene(theNode.getBoundsInLocal());
System.out.println("PRE-MOVE: " + boundsPre);

GridPane.setColumnIndex(theNode, newCol);
GridPane.setRowIndex(theNode, newRow);

baseLayout.layout(); // Causes a layout pass which updates the bounds

Bounds boundsAfter = theNode.localToScene(theNode.getBoundsInLocal());
System.out.println("BOUNDS: " + boundsAfter );

Output:

PRE-MOVE: BoundingBox [minX:25.0, minY:87.0, minZ:0.0, width:243.0, height:116.0, depth:0.0, maxX:268.0, maxY:203.0, maxZ:0.0]
BOUNDS: BoundingBox [minX:25.0, minY:213.0, minZ:0.0, width:243.0, height:116.0, depth:0.0, maxX:268.0, maxY:329.0, maxZ:0.0]

Solution 2

If you do not care to update the bounds right away, observe the boundsInLocal property. This event will fire when JavaFX completes its next layout pass.

theNode.boundsInLocalProperty().addListener((observableValue, bounds, updatedBounds) ->
{
    System.out.println("BOUNDS: " + updatedBounds);
});

Credit

As pointed out by Slaw in the question comments:

So either observe the boundsInLocal property and react when it changes, or call applyCss() followed by layout() on the root of the scene. The first approach is likely "cleaner"