On Tue, Mar 24, 2009 at 11:37 PM, C M <[email protected]> wrote:
> Using mpl 0.98.5.2 in OO mode with wxAgg backend.
>
> I'm trying to make my legends draggable. It works, but
> there is a some inaccuracy with positioning. As I drag it,
> the cursor "outruns" the position of the legend, and that
> error grows the further away from the initial starting point
> the cursor has been moved. It makes the feel of dragging
> completely wrong.
>
> The work of repositioning the legend is done in an
> on_motion event. self.figure here is a mpl Figure.
> The motion event handler is:
>
> #drag the legend
> def on_motion(self, event):
> height = float(self.figure.bbox.height)
> width = float(self.figure.bbox.width)
>
> dx = event.x/width
> dy = event.y/height
>
> if self.gotLegend == 1: #it's picked up
> self.legend._loc=(dx,dy) #reposition it
> self.canvas.draw()
> self.parent.Refresh()
>
Weird. This is essentially what we do, but in our case there's no
problem. I ran your example and experienced the same "outrun"
behavior so I checked to see what was different between yours and
ours.
In ours, we catch the mpl button down event and after establishing a
hit on the legend do:
bbox = self._legend.get_window_extent()
self._dragOffset = (bbox.xmin() - mplEvent.x, bbox.ymin()
- mplEvent.y)
Then in the mousemove event handler we do:
self._moveLegend(mplEvent.x + self._dragOffset[0],
mplEvent.y + self._dragOffset[1])
where self._moveLegend is:
def _moveLegend(self, x, y, autoDraw=True):
height = float(self.figure.bbox.height())
width = float(self.figure.bbox.width())
dx = x/width
dy = y/height
# The following two lines are specific to our implementation
and our internal data classes
self._legendLocation = (dx, dy)
self.plot.getLegend().setLocation(self._legendLocation)
# This is the line that "moves" the legend
self._legend._loc=(dx,dy)
if autoDraw:
self.draw()
Now we're using an ancient version of MPL (0.90.1) and many things
have changed in the meantime. YMMV.
A>
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