Re: [OpenMap Users] NavMouseMode cursor rectangle not redrawing

Hi Scott,

I have exactly the same problem. It stems from the fact that the zoom
box is not drawn on a layer; rather, it is drawn directly into the
mapBean's graphics by the NavMouseMode's mouseDragged() method. This
implies that the zoom box is ONLY drawn when the mouse button is held
down and while the mouse is actively being moved. If you continue to
hold down the button, but stop moving the mouse, no further zoom boxes
are drawn and the last one drawn gets overwritten the next time your
dynamic layers repaint themselves.

There are a couple of ways we could change this:

1. Add a special layer for zoom boxes and other special-purpose
 transient graphics, then make the NavMouseMode draw into this layer
instead of directly into the mapBean's graphics.

2. Add a timer in NavMouseMode that draws the current box at a given
rate starting when mousePressed() is called and stopping when
mouseReleased() is called. Since the box is drawn using XOR mode, this
will effectively make the box "blink" while the cursor is held stationary.

3. Automatically send your own "Pause" event from the mousePressed()
method and a "Resume" event from mouseReleased(). This will look good,
but the downside is that your other objects won't be updated while the
zoom box is active. This may or may not be acceptable for your application.

 Does anybody have any other ideas?

Thanks,

George

sam16@cwru.edu wrote:

>Hi all. I'm using OpenMap to display a bunch of moving objects on a map. The
>user can switch the mouse mode to NavMouseMode and then click and drag to
>recenter and resize the viewing area. When I "pause" the display so that the
>map objects aren't moving, this behavior works fine. But if I have the objects
>running and updating their position, the rectangular box that is created by
>clicking and dragging the cursor disappears on every update of the map objects.
> Once it disappears, the user can make it reappear by continuing to drag the
>cursor, but it disappears again on the next map object update. This makes the
>box flicker. While the zooming/recentering behavior still works, the
>flickering is distracting and makes it hard to figure out where the zoom box is
>actually located. Any ideas on how to fix this behavior? I'm using a
>BufferedMapBean, if that makes a difference.
>
>Thanks,
>Scott
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-- 
George Uecker				george.uecker@dot21rts.com
Software Engineer                       (410) 480-7236
Dot21 Real-Time Systems Inc.            (410) 313-7515 fax
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