/**
* This method tries to automatically determine SRS, bounding box and output size based on the
* layers provided by the user and any other parameters.
*
* <p>If bounds are not specified by the user, they are automatically se to the union of the
* bounds of all layers.
*
* <p>The size of the output image defaults to 512 pixels, the height is automatically determined
* based on the width to height ratio of the requested layers. This is also true if either height
* or width are specified by the user. If both height and width are specified by the user, the
* automatically determined bounding box will be adjusted to fit inside these bounds.
*
* <p>General idea 1) Figure out whether SRS has been specified, fall back to EPSG:4326 2)
* Determine whether all requested layers use the same SRS, - if so, try to do bounding box
* calculations in native coordinates 3) Aggregate the bounding boxes (in EPSG:4326 or native) 4a)
* If bounding box has been specified, adjust height of image to match 4b) If bounding box has not
* been specified, but height has, adjust bounding box
*/
public static void autoSetBoundsAndSize(GetMapRequest getMap) {
// Get the layers
List<MapLayerInfo> layers = getMap.getLayers();
/** 1) Check what SRS has been requested */
String reqSRS = getMap.getSRS();
// if none, try to determine which SRS to use
// and keep track of whether we can use native all the way
boolean useNativeBounds = true;
if (reqSRS == null) {
reqSRS = guessCommonSRS(layers);
forceSRS(getMap, reqSRS);
}
/** 2) Compare requested SRS */
for (int i = 0; useNativeBounds && i < layers.size(); i++) {
if (layers.get(i) != null) {
String layerSRS = layers.get(i).getSRS();
useNativeBounds =
reqSRS.equalsIgnoreCase(layerSRS)
&& layers.get(i).getResource().getNativeBoundingBox() != null;
} else {
useNativeBounds = false;
}
}
CoordinateReferenceSystem reqCRS;
try {
reqCRS = CRS.decode(reqSRS);
} catch (Exception e) {
throw new ServiceException(e);
}
// Ready to determine the bounds based on the layers, if not specified
Envelope aggregateBbox = getMap.getBbox();
boolean specifiedBbox = true;
// If bbox is not specified by request
if (aggregateBbox == null) {
specifiedBbox = false;
// Get the bounding box from the layers
for (int i = 0; i < layers.size(); i++) {
MapLayerInfo layerInfo = layers.get(i);
ReferencedEnvelope curbbox;
try {
curbbox = layerInfo.getLatLongBoundingBox();
if (useNativeBounds) {
ReferencedEnvelope nativeBbox = layerInfo.getBoundingBox();
if (nativeBbox == null) {
try {
CoordinateReferenceSystem nativeCrs = layerInfo.getCoordinateReferenceSystem();
nativeBbox = curbbox.transform(nativeCrs, true);
} catch (Exception e) {
throw new ServiceException("Best effort native bbox computation failed", e);
}
}
curbbox = nativeBbox;
}
} catch (Exception e) {
throw new RuntimeException(e);
}
if (aggregateBbox != null) {
aggregateBbox.expandToInclude(curbbox);
} else {
aggregateBbox = curbbox;
}
}
ReferencedEnvelope ref = null;
// Reproject back to requested SRS if we have to
if (!useNativeBounds && !reqSRS.equalsIgnoreCase(SRS)) {
try {
ref = new ReferencedEnvelope(aggregateBbox, CRS.decode("EPSG:4326"));
aggregateBbox = ref.transform(reqCRS, true);
} catch (ProjectionException pe) {
ref.expandBy(-1 * ref.getWidth() / 50, -1 * ref.getHeight() / 50);
try {
aggregateBbox = ref.transform(reqCRS, true);
} catch (FactoryException e) {
e.printStackTrace();
} catch (TransformException e) {
e.printStackTrace();
}
// And again...
} catch (NoSuchAuthorityCodeException e) {
e.printStackTrace();
} catch (TransformException e) {
e.printStackTrace();
} catch (FactoryException e) {
e.printStackTrace();
}
}
}
// Just in case
if (aggregateBbox == null) {
forceSRS(getMap, DefaultWebMapService.SRS);
aggregateBbox = DefaultWebMapService.BBOX;
}
// Start the processing of adjust either the bounding box
// or the pixel height / width
double bbheight = aggregateBbox.getHeight();
double bbwidth = aggregateBbox.getWidth();
double bbratio = bbwidth / bbheight;
double mheight = getMap.getHeight();
double mwidth = getMap.getWidth();
if (mheight > 0.5 && mwidth > 0.5 && specifiedBbox) {
// This person really doesnt want our help,
// we'll warp it any way they like it...
} else {
if (mheight > 0.5 && mwidth > 0.5) {
// Fully specified, need to adjust bbox
double mratio = mwidth / mheight;
// Adjust bounds to be less than ideal to meet spec
if (bbratio > mratio) {
// Too wide, need to increase height of bb
double diff = ((bbwidth / mratio) - bbheight) / 2;
aggregateBbox.expandBy(0, diff);
} else {
// Too tall, need to increase width of bb
double diff = ((bbheight * mratio) - bbwidth) / 2;
aggregateBbox.expandBy(diff, 0);
}
adjustBounds(reqSRS, aggregateBbox);
} else if (mheight > 0.5) {
mwidth = bbratio * mheight;
} else {
if (mwidth > 0.5) {
mheight = (mwidth / bbratio >= 1) ? mwidth / bbratio : 1;
} else {
if (bbratio > 1) {
mwidth = MAX_SIDE;
mheight = (mwidth / bbratio >= 1) ? mwidth / bbratio : 1;
} else {
mheight = MAX_SIDE;
mwidth = (mheight * bbratio >= 1) ? mheight * bbratio : 1;
}
// make sure OL output height is sufficient to show the OL scale bar fully
if (mheight < MIN_OL_HEIGHT
&& ("application/openlayers".equalsIgnoreCase(getMap.getFormat())
|| "openlayers".equalsIgnoreCase(getMap.getFormat()))) {
mheight = MIN_OL_HEIGHT;
mwidth = (mheight * bbratio >= 1) ? mheight * bbratio : 1;
}
}
}
// Actually set the bounding box and size of image
getMap.setBbox(aggregateBbox);
getMap.setWidth((int) mwidth);
getMap.setHeight((int) mheight);
}
}
