# coyote: CGKML_SCREENOVERLAY__DEFINE

- coyote/Graphics
- coyote/FileIO
- [Source code]

Description

      This program implements the KML ScreenOverlay element. For
      reference, see  the `Google KML Reference Documentation <https://developers.google.com/kml/documentation/kmlreference#ScreenOverlay>`.
      A ScreenOverlay element draws an image onto the Google Earth display or screen.

Categories

      Graphics, FileIO

Examples

      See the `cgKML_File` object for examples of how to create a KML file.

Author

      FANNING SOFTWARE CONSULTING::
         David W. Fanning
         1645 Sheely Drive
         Fort Collins, CO 80526 USA
         Phone: 970-221-0438
         E-mail: david@idlcoyote.com
         Coyote's Guide to IDL Programming: http://www.idlcoyote.com

History

      Change History::
         Written, 3 November 2012 by David W. Fanning.

Copyright

      Copyright (c) 2012, Fanning Software Consulting, Inc.
      e purpose of this method is to establish an abstract KML ScreenOverlay class. For reference, see
      tps://developers.google.com/kml/documentation/kmlreference?hl=fr#ScreenOverlay.

Keywords

      overlay_xy: in, required, type=dblarr
          This keyword specifies a point [x,y] in the image overlay that is mapped to the
          screen coordinate `Screen_XY`. The location of the point is specified by the values
          in `Overlay_Units_X` and 'Overlay_Units_Y`.
      overlay_unit_x: in, optional, type=string, default='fraction'
          Three values are possible: (1) "fraction" indicates that the X value is a fraction of the image;
          (2) "pixels" indicates the the X value is in pixels; and (3) "insetPixels" indicates the X
          value is an indent from the right edge of the image.
      overlay_unit_y: in, optional, type=string, default='fraction'
          Three values are possible: (1) "fraction" indicates that the Y value is a fraction of the image;
          (2) "pixels" indicates the the Y value is in pixels; and (3) "insetPixels" indicates the Y
          value is an indent from the top edge of the image.
      rotation: in, optional, type=double, default=0.0
          This keyword indicates the angle of rotation of the screen overlay in degrees counterclockwise
          from North. A value from -180 to 180.
      screen_xy: in, optional, type=dblarr
          This keyword specifies a point [x,y] relative to the screen origin that the overlay image
          is mapped to. The location of the point is specified by the values in `XUnits` and 'YUnits`.
      screen_unit_x: in, optional, type=string, default='fraction'
          Three values are possible: (1) "fraction" indicates that the X value is a fraction of the image;
          (2) "pixels" indicates the the X value is in pixels; and (3) "insetPixels" indicates the X
          value is an indent from the right edge of the image.
      screen_unit_y: in, optional, type=string, default='fraction'
          Three values are possible: (1) "fraction" indicates that the Y value is a fraction of the image;
          (2) "pixels" indicates the the Y value is in pixels; and (3) "insetPixels" indicates the Y
          value is an indent from the top edge of the image.
      size_xy: in, required, type=dblarr
          This keyword specifies the size of the image for the screen overlay as follows. A -1
          indicates to use the native dimensions of the image. A 0 indicates that the aspect ratio
          of the image should be preserved. Any other value sets the output dimension of the image,
          according to the "unit" values.
      size_unit_x: in, optional, type=string, default='fraction'
          Three values are possible: (1) "fraction" indicates that the X value is a fraction of the image;
          (2) "pixels" indicates the the X value is in pixels; and (3) "insetPixels" indicates the X
          value is an indent from the right edge of the image.
      size_unit_y: in, optional, type=string, default='fraction'
          Three values are possible: (1) "fraction" indicates that the Y value is a fraction of the image;
          (2) "pixels" indicates the the Y value is in pixels; and (3) "insetPixels" indicates the Y
          value is an indent from the top edge of the image.
      _ref_extra: out, optional
          Any keywords for the superclass objects are allowed.
      e purpose of this method is to destroy anything we created that may leak
      mory or need to be released from use.
      e cgKML_ScreenOverlay class definition module. It is a container object and
      presents part of the KML file hierarchy.

Params

      class: out, optional, type=structure
          The class definition returned as a structure variable. Occassionally useful.