Android zoomToSpan for MapsForge map

Question

MapsForge map 是否存在 zoomToSpan 方法？如果不存在，我该如何实现？有没有一些代码示例或算法描述？

提前致谢

Answer 1

您可以使用以下方法扩展 MapView(MapsForge 版本 0.3.1):

public synchronized void fitToBoundingBox(final BoundingBox pBoundingBox, final int pMaximumZoom) {
    int width = this.getWidth();
    int height = this.getHeight();
    if (width <= 0 || height <= 0) {
        this.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                MapView.this.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                fitToBoundingBox(pBoundingBox, pMaximumZoom);
            }
        });
    } else {
        Projection projection1 = this.getProjection();
        GeoPoint pointSouthWest = new GeoPoint(pBoundingBox.minLatitude, pBoundingBox.minLongitude);
        GeoPoint pointNorthEast = new GeoPoint(pBoundingBox.maxLatitude, pBoundingBox.maxLongitude);
        Point pointSW = new Point();
        Point pointNE = new Point();
        byte maxLvl = (byte) Math.min(pMaximumZoom, this.getMapZoomControls().getZoomLevelMax());
        byte zoomLevel = 0;
        while (zoomLevel < maxLvl) {
            byte tmpZoomLevel = (byte) (zoomLevel + 1);
            projection1.toPoint(pointSouthWest, pointSW, tmpZoomLevel);
            projection1.toPoint(pointNorthEast, pointNE, tmpZoomLevel);
            if (pointNE.x - pointSW.x > width) {
                break;
            }
            if (pointSW.y - pointNE.y > height) {
                break;
            }
            zoomLevel = tmpZoomLevel;
        }
        this.getMapViewPosition().setMapPosition(new MapPosition(pBoundingBox.getCenterPoint(), zoomLevel));
    }
}

很可能您有一组应该显示在 map 上的叠加层。您必须找到经度和纬度的“最小”和“最大”值，然后调用上面的方法:

mapView.fitToBoundingBox(new BoundingBox(minLat, minLng, maxLat, maxLng), 20);

已经找到这个解决方案here