Swing JxMapViewer: focus on a object and set corresponding zoom level

问题

I trying to integrate JxMapViewer into my swing application.

I have drawn a line on the map between two way points. Now I wish to implement a functionality like:

Wherever I am on a map, whatever zoom level is set, whenever i click on a button (or some external event), focus should be shifted to line i have drawn (i.e. indirectly on the two waypoints)

Secondly, the zoom level should be set such that portion of a map containing those two waypoints should be visible.

I see that we have getViewportBounds method inside JxMApViewer class. Similarly we do not have setViewportBounds. In that case we could have calculated a rectangle which encompasses those two waypoints and set it.

Any hint would be appreciated

I have modified existing calculateZoomFrom method as:

int zoom = mainMap.getZoom();
Rectangle2D inner = generateBoundedRectangleForLine(positionSet, mainMap.getZoom());

int count = 0;
Rectangle outer = mainMap.getViewportBounds();
while(!outer.contains(inner) || (outer.contains(inner) && !(inner.getHeight() >= mainMap.getHeight() - 50))) {
    Point2D center = new Point2D.Double(
            inner.getX() + inner.getWidth()/2,
            inner.getY() + inner.getHeight()/2);
    GeoPosition px = mainMap.getTileFactory().pixelToGeo(center,zoom);
    mainMap.setCenterPosition(px);
    count++;
    if(count > 30) break;
    if(outer.contains(inner)) {
        if (!(inner.getHeight() >= mainMap.getHeight() - 50)) {
            zoom = zoom - 1;
            if(zoom < 1) {
                break;
            }
        } else {
            break;
        }

    } else {
        zoom = zoom + 1;
        if(zoom > 15) {
            break;
        }
    }

    mainMap.setZoom(zoom);
    inner = generateBoundedRectangleForLine(positionSet, zoom);
}

But it is not working.

回答1:

You can call JXMapViewer.setCenterPosition(GeoPosition geoPosition) from your ActionListener for that.

You would have to calculate the appropriate zoom level yourself (JXMapViewer doesn't offer anything for that as far as I know). Since you know the coordinates of the waypoint, calculating the bounding box and setting the appropriate zoom level shouldn't be a problem.

回答2:

I found the solution. Solution was to set zoom level to the lowest one and then call calculateZoomFrom method.

来源：https://stackoverflow.com/questions/10959703/swing-jxmapviewer-focus-on-a-object-and-set-corresponding-zoom-level

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java

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jxmapviewer