On Thu, Mar 5, 2009 at 11:01 AM, Emily Gouge <[email protected]>
wrote:
Hey Jody,
What I have done is update the Mapgraphic Renderer to render the
entire
viewport onto a single image. This image is then stored on the layer
blackboard and used when rendering tiles. When the tile comes
along to
render the mapgraphic the image is taken off the blackboard and
the part
that matches the tiles bounds are clipped and drawn.
Yeah cool - I like that approach - nice work. If we are smart when we
define
MapGraphic2 we may be able to define a smaller image (along with the
screen
location the image should be drawn in).
We may also find it useful to split up ScreenGraphic from
MapGraphic (and
have screen graphic always work in screen coords; and MapGraphic
work in
some data coords (we could default to DefaultGeoGraphicCRS.WGS84 to
make
examples easy to write).
In anycase I like the approach you describe.
In order to make this work; when the mapgraphic context is created a
viewport listener is added to the map so when the viewport bounds
change
the
image cached on the layer's blackboard is cleared.
Smart. You could also consider using the MapGraphicRenderer -
because it
is
a Renderer it has lifecycle methods (ie is stateful) and you can
add/remove
your viewport listener there.
The issues with the styling is not that layer.refresh() is not being
called
but rather that this doesn't cause my "cached" mapgraphic image on
the
blackboard to be cleared.
I see so we have one step remaining to do ... when the
MapGraphicRenderer
gets a layer refresh event it needs to clear this image. It is the
Renderer
that would have this responsibility rather than the MapGraphic
implementations themselves.
That is the next step right? Am I missing something?
A simple solution would be do not cache this image; but I can't
imagine
that would be very good performance wise as it would be rendering the
image
multiple times.
Agreed.
I could add another listener that listeners for style events and
clears
the
cache.
Apparently I am not missing something; you have the same idea - I
would
listen to layer.refresh events rather than style events. Style change
events
trigger a layer refresh event do they not?
Or maybe I could store information about the styles with my cached
image
and if they have changed then refresh the cached mapgraphic.
The style blackboard provides the notification; many of the style
objects
are just simple data structures (and thus hard to watch change).
Cheers,
Jody
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