Reorder the children of a gTree
Change the order in which the children of a gTree get drawn.
A gPath object specifying a gTree within the current scene.
A gTree object to be modified.
A character vector or a numeric vector that specifies the new drawing order for the children of the gTree. May not refer to all children of the gTree (see Details).
Controls what happens when the
Should the modified scene be redrawn?
In the simplest case,
order specifies a new ordering for all of
the children of the gTree. The children may be specified either by
name or by existing numerical order.
order does not
specify all children of the gTree then, by default, the children
order are drawn first and then all remaining
children are drawn. If
back=FALSE then the children not
order are drawn first, followed by the specified
children. This makes it easy to specify a send-to-back or
bring-to-front reordering. The
order argument is always
in back-to-front order.
It is not possible to reorder the grid display list (the top-level
grobs in the current scene) because the display list is a mixture of
grobs and viewports (so it is not clear what reordering even means and
it would be too easy to end up with a scene that would not draw).
If you want to reorder the grid display list, try
to create a gTree and then reorder (and redraw) that gTree.
grid.reorder() is called for its side-effect of modifying the
reorderGrob() returns the modified gTree.
This function may return a gTree that will not draw. For example, a
gTree has two children, A and B (in that order),
and the width of child B depends on the width of child A (e.g., a box
around a piece of text). Switching the order so that B is drawn
before A will not allow B to be drawn. If this happens with
grid.reorder(), the modification will not be performed. If
this happens with
reorderGrob() it should be possible simply to
restore the original order.
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# gTree with two children, "red-rect" and "blue-rect" (in that order) gt <- gTree(children=gList( rectGrob(gp=gpar(col=NA, fill="red"), width=.8, height=.2, name="red-rect"), rectGrob(gp=gpar(col=NA, fill="blue"), width=.2, height=.8, name="blue-rect")), name="gt") grid.newpage() grid.draw(gt) # Spec entire order as numeric (blue-rect, red-rect) grid.reorder("gt", 2:1) # Spec entire order as character grid.reorder("gt", c("red-rect", "blue-rect")) # Only spec the one I want behind as character grid.reorder("gt", "blue-rect") # Only spec the one I want in front as character grid.reorder("gt", "blue-rect", back=FALSE)