C++ (Cpp) champlain_map_source_get_row_count示例

示例#1

文件： champlain-path-layer.c 项目： StanciuMarius/Libchamplain-map-wrapping

static void
get_map_size (ChamplainView *view, gint *width, gint *height)
{
  gint size, rows, cols;
  ChamplainMapSource *map_source = champlain_view_get_map_source (view);
  gint zoom_level = champlain_view_get_zoom_level (view);
  size = champlain_map_source_get_tile_size (map_source);
  rows = champlain_map_source_get_row_count (map_source,
                                                zoom_level);
  cols = champlain_map_source_get_column_count (map_source,
                                                zoom_level);
  *width = size * rows;
  *height = size * cols;

}

示例#2

文件： champlain-map-source.c 项目： PabloCastellano/libchamplain

/**
 * champlain_map_source_get_meters_per_pixel:
 * @map_source: a #ChamplainMapSource
 * @zoom_level: the zoom level
 * @latitude: a latitude
 * @longitude: a longitude
 *
 * Gets meters per pixel at the position on the map using this map source's projection.
 *
 * Returns: the meters per pixel
 *
 * Since: 0.4.3
 */
gdouble
champlain_map_source_get_meters_per_pixel (ChamplainMapSource *map_source,
    guint zoom_level,
    gdouble latitude,
    G_GNUC_UNUSED gdouble longitude)
{
  g_return_val_if_fail (CHAMPLAIN_IS_MAP_SOURCE (map_source), 0.0);

  /*
   * Width is in pixels. (1 px)
   * m/px = radius_at_latitude / width_in_pixels
   * k = radius of earth = 6 378.1 km
   * radius_at_latitude = 2pi * k * sin (pi/2-theta)
   */

  gdouble tile_size = champlain_map_source_get_tile_size (map_source);
  /* FIXME: support other projections */
  return 2.0 *M_PI *EARTH_RADIUS *sin (M_PI / 2.0 - M_PI / 180.0 *latitude) /
         (tile_size * champlain_map_source_get_row_count (map_source, zoom_level));
}