C++ TileSource::hasDataAtLOD方法代码示例

//.........这里部分代码省略.........

    for (unsigned int level = _minLevel; level <= _maxLevel; level++)
    {
        double coverageRatio = 0.0;

        if (_extents.empty())
        {
            unsigned int wide, high;
            map->getProfile()->getNumTiles( level, wide, high );
            _total += (wide * high);
        }
        else
        {
            for (std::vector< GeoExtent >::const_iterator itr = _extents.begin(); itr != _extents.end(); itr++)
            {
                const GeoExtent& extent = *itr;
                double boundsArea = extent.area();

                TileKey ll = map->getProfile()->createTileKey(extent.xMin(), extent.yMin(), level);
                TileKey ur = map->getProfile()->createTileKey(extent.xMax(), extent.yMax(), level);

                int tilesWide = ur.getTileX() - ll.getTileX() + 1;
                int tilesHigh = ll.getTileY() - ur.getTileY() + 1;
                int tilesAtLevel = tilesWide * tilesHigh;
                //OE_NOTICE << "Tiles at level " << level << "=" << tilesAtLevel << std::endl;

                bool hasData = false;

                for (ImageLayerVector::const_iterator itr = mapf.imageLayers().begin(); itr != mapf.imageLayers().end(); itr++)
                {
                    TileSource* src = itr->get()->getTileSource();
                    if (src)
                    {
                        if (src->hasDataAtLOD( level ))
                        {
                            //Compute the percent coverage of this dataset on the current extent
                            if (src->getDataExtents().size() > 0)
                            {
                                double cov = 0.0;
                                for (unsigned int j = 0; j < src->getDataExtents().size(); j++)
                                {
                                    GeoExtent b = src->getDataExtents()[j].transform( extent.getSRS());
                                    GeoExtent intersection = b.intersectionSameSRS( extent );
                                    if (intersection.isValid())
                                    {
                                        double coverage = intersection.area() / boundsArea;
                                        cov += coverage; //Assumes the extents aren't overlapping                            
                                    }
                                }
                                if (coverageRatio < cov) coverageRatio = cov;
                            }
                            else
                            {
                                //We have no way of knowing how much coverage we have
                                coverageRatio = 1.0;
                            }
                            hasData = true;
                            break;
                        }
                    }
                }

                for (ElevationLayerVector::const_iterator itr = mapf.elevationLayers().begin(); itr != mapf.elevationLayers().end(); itr++)
                {
                    TileSource* src = itr->get()->getTileSource();
                    if (src)

GeoImage
ImageLayer::createImageFromTileSource(const TileKey&    key,
                                      ProgressCallback* progress,
                                      bool              forceFallback,
                                      bool&             out_isFallback)
{
    // Results:
    // 
    // * return an osg::Image matching the key extent is all goes well;
    //
    // * return NULL to indicate that the key exceeds the maximum LOD of the source data,
    //   and that the engine may need to generate a "fallback" tile if necessary;
    //
    // deprecated:
    // * return an "empty image" if the LOD is valid BUT the key does not intersect the
    //   source's data extents.

    out_isFallback = false;

    TileSource* source = getTileSource();
    if ( !source )
        return GeoImage::INVALID;

    // If the profiles are different, use a compositing method to assemble the tile.
    if ( !key.getProfile()->isEquivalentTo( getProfile() ) )
    {
        return assembleImageFromTileSource( key, progress, out_isFallback );
    }

    // Fail is the image is blacklisted.
    // ..unless there will be a fallback attempt.
    if ( source->getBlacklist()->contains( key.getTileId() ) && !forceFallback )
    {
        OE_DEBUG << LC << "createImageFromTileSource: blacklisted(" << key.str() << ")" << std::endl;
        return GeoImage::INVALID;
    }

    // Fail if no data is available for this key.
    if ( !source->hasDataAtLOD( key.getLevelOfDetail() ) && !forceFallback )
    {
        OE_DEBUG << LC << "createImageFromTileSource: hasDataAtLOD(" << key.str() << ") == false" << std::endl;
        return GeoImage::INVALID;
    }

    if ( !source->hasDataInExtent( key.getExtent() ) )
    {
        OE_DEBUG << LC << "createImageFromTileSource: hasDataInExtent(" << key.str() << ") == false" << std::endl;
        return GeoImage::INVALID;
    }

    // Good to go, ask the tile source for an image:
    osg::ref_ptr<TileSource::ImageOperation> op = _preCacheOp;

    osg::ref_ptr<osg::Image> result;
    TileKey finalKey = key;
    bool fellBack = false;

    if ( forceFallback )
    {        
        while( !result.valid() && finalKey.valid() )
        {
            if ( !source->getBlacklist()->contains( finalKey.getTileId() ) )
            {
                result = source->createImage( finalKey, op.get(), progress );
                if ( result.valid() )
                {
                    if ( finalKey.getLevelOfDetail() != key.getLevelOfDetail() )
                    {
                        // crop the fallback image to match the input key, and ensure that it remains the
                        // same pixel size; because chances are if we're requesting a fallback that we're
                        // planning to mosaic it later, and the mosaicer requires same-size images.
                        GeoImage raw( result.get(), finalKey.getExtent() );
                        GeoImage cropped = raw.crop( key.getExtent(), true, raw.getImage()->s(), raw.getImage()->t(), *_runtimeOptions.driver()->bilinearReprojection() );
                        result = cropped.takeImage();
                        fellBack = true;
                    }
                }
            }
            if ( !result.valid() )
            {
                finalKey = finalKey.createParentKey();
                out_isFallback = true;
            }
        }

        if ( !result.valid() )
        {
            result = 0L;
            //result = _emptyImage.get();
            finalKey = key;
        }
    }

    else
    {
        result = source->createImage( key, op.get(), progress );
    }

    // Process images with full alpha to properly support MP blending.
    if ( result != 0L )
//.........这里部分代码省略.........