C++ query::get_filter_factor方法代码示例

feature_ptr gdal_featureset::get_feature(mapnik::query const& q)
{
    feature_ptr feature = feature_factory::create(ctx_,1);
    int raster_has_nodata = 0;
    double raster_nodata = 0;
    GDALRasterBand * red = 0;
    GDALRasterBand * green = 0;
    GDALRasterBand * blue = 0;
    GDALRasterBand * alpha = 0;
    GDALRasterBand * grey = 0;
    CPLErr raster_io_error = CE_None;

    /*
#ifdef MAPNIK_LOG
      double tr[6];
      dataset_.GetGeoTransform(tr);

      const double dx = tr[1];
      const double dy = tr[5];
      MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: dx_=" << dx_ << " dx=" << dx << " dy_=" << dy_ << "dy=" << dy;
#endif
    */

    view_transform t(raster_width_, raster_height_, raster_extent_, 0, 0);
    box2d<double> intersect = raster_extent_.intersect(q.get_bbox());
    box2d<double> box = t.forward(intersect);

    //size of resized output pixel in source image domain
    double margin_x = 1.0 / (std::fabs(dx_) * std::get<0>(q.resolution()));
    double margin_y = 1.0 / (std::fabs(dy_) * std::get<1>(q.resolution()));
    if (margin_x < 1)
    {
        margin_x = 1.0;
    }
    if (margin_y < 1)
    {
        margin_y = 1.0;
    }

    //select minimum raster containing whole box
    int x_off = rint(box.minx() - margin_x);
    int y_off = rint(box.miny() - margin_y);
    int end_x = rint(box.maxx() + margin_x);
    int end_y = rint(box.maxy() + margin_y);

    //clip to available data
    if (x_off < 0)
    {
        x_off = 0;
    }
    if (y_off < 0)
    {
        y_off = 0;
    }
    if (end_x > (int)raster_width_)
    {
        end_x = raster_width_;
    }
    if (end_y > (int)raster_height_)
    {
        end_y = raster_height_;
    }
    int width = end_x - x_off;
    int height = end_y - y_off;

    // don't process almost invisible data
    if (box.width() < 0.5)
    {
        width = 0;
    }
    if (box.height() < 0.5)
    {
        height = 0;
    }

    //calculate actual box2d of returned raster
    box2d<double> feature_raster_extent(x_off, y_off, x_off + width, y_off + height);
    intersect = t.backward(feature_raster_extent);

    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Raster extent=" << raster_extent_;
    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: View extent=" << intersect;
    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Query resolution=" << std::get<0>(q.resolution()) << "," << std::get<1>(q.resolution());
    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: StartX=" << x_off << " StartY=" << y_off << " Width=" << width << " Height=" << height;

    if (width > 0 && height > 0)
    {
        double width_res = std::get<0>(q.resolution());
        double height_res = std::get<1>(q.resolution());
        int im_width = int(width_res * intersect.width() + 0.5);
        int im_height = int(height_res * intersect.height() + 0.5);

        double filter_factor = q.get_filter_factor();
        im_width = int(im_width * filter_factor + 0.5);
        im_height = int(im_height * filter_factor + 0.5);

        // case where we need to avoid upsampling so that the
        // image can be later scaled within raster_symbolizer
        if (im_width >= width || im_height >= height)
        {
            im_width = width;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
    }
    if (box.height() < 0.5)
    {
        height = 0;
    }

    //calculate actual box2d of returned raster
    box2d<double> feature_raster_extent(x_off, y_off, x_off + width, y_off + height);
    intersect = t.backward(feature_raster_extent);

    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Raster extent=" << raster_extent_;
    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: View extent=" << intersect;
    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Query resolution=" << boost::get<0>(q.resolution()) << "," << boost::get<1>(q.resolution());
    MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: StartX=" << x_off << " StartY=" << y_off << " Width=" << width << " Height=" << height;

    if (width > 0 && height > 0)
    {
        double width_res = boost::get<0>(q.resolution());
        double height_res = boost::get<1>(q.resolution());
        int im_width = int(width_res * intersect.width() + 0.5);
        int im_height = int(height_res * intersect.height() + 0.5);

        // if layer-level filter_factor is set, apply it
        if (filter_factor_)
        {
            im_width *= filter_factor_;
            im_height *= filter_factor_;

            MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Applying layer filter_factor=" << filter_factor_;
        }
        // otherwise respect symbolizer level factor applied to query, default of 1.0
        else
        {
            double sym_downsample_factor = q.get_filter_factor();
            im_width *= sym_downsample_factor;
            im_height *= sym_downsample_factor;
        }

        // case where we need to avoid upsampling so that the
        // image can be later scaled within raster_symbolizer
        if (im_width >= width || im_height >= height)
        {
            im_width = width;
            im_height = height;
        }

        if (im_width > 0 && im_height > 0)
        {
            mapnik::raster_ptr raster = boost::make_shared<mapnik::raster>(intersect, im_width, im_height);
            feature->set_raster(raster);
            mapnik::image_data_32 & image = raster->data_;
            image.set(0xffffffff);

            MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Image Size=(" << im_width << "," << im_height << ")";
            MAPNIK_LOG_DEBUG(gdal) << "gdal_featureset: Reading band=" << band_;

            if (band_ > 0) // we are querying a single band
            {
                if (band_ > nbands_)
                {
                    throw datasource_exception((boost::format("GDAL Plugin: '%d' is an invalid band, dataset only has '%d' bands\n") % band_ % nbands_).str());
                }

                float* imageData = (float*)image.getBytes();
                GDALRasterBand * band = dataset_.GetRasterBand(band_);
                int hasNoData(0);

feature_ptr gdal_featureset::get_feature(mapnik::query const& q)
{
    feature_ptr feature(new Feature(1));

    GDALRasterBand * red = 0;
    GDALRasterBand * green = 0;
    GDALRasterBand * blue = 0;
    GDALRasterBand * alpha = 0;
    GDALRasterBand * grey = 0; 
   
    /*
    double tr[6];
    dataset_.GetGeoTransform(tr);
    
    double dx = tr[1];
    double dy = tr[5];
    std::clog << "dx_: " << dx_ << " dx: " << dx << " dy_: " << dy_ << "dy: " << dy << "\n";
    */
          
    CoordTransform t(raster_width_,raster_height_,raster_extent_,0,0);
    box2d<double> intersect = raster_extent_.intersect(q.get_bbox());
    box2d<double> box = t.forward(intersect);

    //size of resized output pixel in source image domain
    double margin_x = 1.0/(fabs(dx_)*boost::get<0>(q.resolution()));
    double margin_y = 1.0/(fabs(dy_)*boost::get<1>(q.resolution()));
    if (margin_x < 1)
        margin_x = 1.0;
    if (margin_y < 1)
        margin_y = 1.0;
    //select minimum raster containing whole box
    int x_off = rint(box.minx() - margin_x);
    int y_off = rint(box.miny() - margin_y);
    int end_x = rint(box.maxx() + margin_x);
    int end_y = rint(box.maxy() + margin_y);
    //clip to available data
    if (x_off < 0)
        x_off = 0;
    if (y_off < 0)
        y_off = 0;
    if (end_x > (int)raster_width_)
        end_x = raster_width_;
    if (end_y > (int)raster_height_)
        end_y = raster_height_;
    int width = end_x - x_off;
    int height = end_y - y_off;
    // don't process almost invisible data
    if (box.width() < 0.5)
        width = 0;
    if (box.height() < 0.5)
        height = 0;
    //calculate actual box2d of returned raster
    box2d<double> feature_raster_extent(x_off, y_off, x_off+width, y_off+height); 
    intersect = t.backward(feature_raster_extent);
    
#ifdef MAPNIK_DEBUG         
    std::clog << "GDAL Plugin: Raster extent=" << raster_extent_ << std::endl;
    std::clog << "GDAL Plugin: View extent=" << intersect << std::endl;
    std::clog << "GDAL Plugin: Query resolution=" << boost::get<0>(q.resolution()) << "," << boost::get<1>(q.resolution()) << std::endl;
    std::clog << boost::format("GDAL Plugin: StartX=%d StartY=%d Width=%d Height=%d") % x_off % y_off % width % height << std::endl;
#endif
   
    if (width > 0 && height > 0)
    {
        double width_res = boost::get<0>(q.resolution());
        double height_res = boost::get<1>(q.resolution());
        int im_width = int(width_res * intersect.width() + 0.5);
        int im_height = int(height_res * intersect.height() + 0.5);
        
        // if layer-level filter_factor is set, apply it
        if (filter_factor_)
        {
            im_width *= filter_factor_;
            im_height *= filter_factor_;
        }
        // otherwise respect symbolizer level factor applied to query, default of 1.0
        else
        {
            double sym_downsample_factor = q.get_filter_factor();
            im_width *= sym_downsample_factor;
            im_height *= sym_downsample_factor;
        }

        // case where we need to avoid upsampling so that the
        // image can be later scaled within raster_symbolizer 
        if (im_width >= width || im_height >= height)
        {
            im_width = width;
            im_height = height;
        }

        if (im_width > 0 && im_height > 0)
        {
            mapnik::image_data_32 image(im_width, im_height);
            image.set(0xffffffff); 
             
#ifdef MAPNIK_DEBUG
            std::clog << "GDAL Plugin: Image Size=(" << im_width << "," << im_height << ")" << std::endl;
            std::clog << "GDAL Plugin: Reading band " << band_ << std::endl;
#endif
//.........这里部分代码省略.........