/**
* Computes actual grid specification (origin + single cell width and height) in the coordinates
* relative to the diagram content pane.
*
* <p>This specification depends only on the grid-relative properties stored in the {@link
* EditPartViewer}, so client may cache it and rely on {@link
* EditPartViewer#addPropertyChangeListener(PropertyChangeListener)}
*
* @param viewer
* @return grid specification in the coordinate system relative to diagram content pane, or <code>
* null</code> if grid is not enabled
*/
private static PrecisionRectangle getRelativeGridSpec(EditPartViewer viewer) {
Boolean enabled = (Boolean) viewer.getProperty(SnapToGrid.PROPERTY_GRID_ENABLED);
if (enabled == null || !enabled) {
return null;
}
double gridX = 0;
double gridY = 0;
Dimension spacing = (Dimension) viewer.getProperty(SnapToGrid.PROPERTY_GRID_SPACING);
if (spacing != null) {
gridX = spacing.preciseWidth();
gridY = spacing.preciseHeight();
}
if (gridX <= 0) {
gridX = SnapToGrid.DEFAULT_GRID_SIZE;
}
if (gridY <= 0) {
gridY = SnapToGrid.DEFAULT_GRID_SIZE;
}
Point origin = (Point) viewer.getProperty(SnapToGrid.PROPERTY_GRID_ORIGIN);
PrecisionRectangle result =
new PrecisionRectangle( //
origin == null ? 0 : origin.preciseX(),
origin == null ? 0 : origin.preciseY(),
gridX,
gridY);
return result;
}
