# coyote: CGGOOGLEMAPWIDGET

- coyote/Graphics
- coyote/Widget Programming
- [Source code]

Description

      This is the driver for the cgGoogleMapWidget object, which is a compound widget
      object that obtains a Google static map from Google Maps and displays it in the
      program's draw widget window. It can be used either as a stand-alone program or
      to create a map image in draw widget in a larger widget program.
      This program implements a subset of the Google Static Map API, which can be found in
      more detail here: https://developers.google.com/maps/documentation/staticmaps/. The
      program works by building a URL for a map image. A connection to the Internet is
      required to then request a map image (in GIF, JPEG or PNG format) to be returned from
      Google Maps. The returned image is then read and loaded into a draw widget window
      of the right size for the returned map image. The default is to delete the image file
      that is created, but the user can also set keywords to retain the image that is downloaded
      from Google Maps. Users are able to control button and motion events in the resulting
      draw widget with their own event handler module. A cgMap coordinate object is created
      to establish a map reference coordinate system on top of the returned map image, allowing
      other map information to be drawn on top of the returned map image.

Categories

      Graphics, Widgets

Params

      parent: in, optional, type=long
           The identifier of the parent widget of the draw widget that is going to be
           created by the program. If not provided, the program will create its own
           top-level base widget as the parent.

Keywords

      box_axes: in, optional, type=boolean, default=0
          Set this keyword to draw box axes around the Google Map.
      button_events: in, optional, type=boolean, default=0
          Set this keyword to turn button events on for the draw widget in the program.
      center_latitude: in, optional, type=float, default=40.60
          The center latitude of the requested Google map. If not provided, the latitude of
          Fort Collins, Colorado, home of Coyote. Latitudes are only recognized to four
          decimals values of precision.
      center_longitude: in, optional, type=float, default=-105.10
          The center longitude of the requested Google map. If not provided, the longitude of
          Fort Collins, Colorado, home of Coyote. Longitude are only recognized to four
          decimals values of precision.
      event_method: in, optional, type='string'
          The name of the event handler method for the draw widget. If you use this keyword,
          you will also need to write this event handler module. It gets sent one positional
          parameter, the event structure created by the draw widget.
      event_pro: in, optional, type='string'
          The name of an external event handler procedure for the draw widget. The event handler
          procedure gets sent one positional parameter, the event structure created by the draw widget.
      imagetype: in, optional, type=string, default='png32'
          The type of image format the Google map should be returned in. The default is
          a 32-bit full color PNG file. The image types are given in the Google Static Map
          API documentation and are as follows: png or png8, png32, gif, jpg, and jpg-baseline.
      keep_image: in, optional, type=boolean, default=0
          Set this keyword if you wish to save the Google map as an image when the object
          is destroyed.
      maptype: in, optional, type=string, default='terrain'
          Set this keyword to the type of map you wish to retrieve from Google Maps. The
          choices are listed in the Google Static Map API documentation and are: "roadmap",
          "terrain", "satellite", and "hybrid".
      markers: in, optional, type=structure
          A scalar or array of cgGoogleMapMarker structures. If present, the markers will
          be requested with the map from Google. The cgGoogleMapMarker structure is defined
          like this::
             struct = { cgGOOGLEMAPMARKER, $
                size: "", $         ; The marker size ("tiny", "small", "mid" or "normal")
                color: "", $        ; A color name as provided by cgColor.
                label: "", $        ; A single uppercase character label from the set {A-Z,0-9}.
                lats: Ptr_New(), $  ; A pointer to one or more latitude values.
                lons: Ptr_New() }   ; A pointer to one or more longitude values.
          Note that the user will be responsible for freeing the pointers in the MARKERS
          structure. This program will not do that.
      motion_events: in, optional, type=boolean, default=0
          Set this keyword to turn motion events on for the draw widget in the program.
      tempDir: in, optional, type=string
          The directory where the image containing the Google map is written. By default,
          it is obtained from the environment like this: tempdir = GetEnv('IDL_TMPDIR').
      visiblemarkers: in, optional, type=boolean, default=1
          Set this keyword to 0 to temporarily turn off the display of the markers. Normally,
          markers are drawn (if present), unless this flag is set to 0.
      xsize: in, optional, type=int, default=600
          The X size of the program's draw widget. A maximum of 690 if box axes are requested
          and a maximum of 640 if no box axes are requested. Box axes require a 25 pixel border
          and the maximum size of a Google Map is 640 pixels.
      ysize: in, optional, type=int, default=600
          The Y size of the program's draw widget. A maximum of 690 if box axes are requested
          and a maximum of 640 if no box axes are requested. Box axes require a 25 pixel border
          and the maximum size of a Google Map is 640 pixels.
      zoomlevel: in, optional, type=integer, default=12
          The zoom level of the requested Google map. Should be an integer between 0 and 21.

Returns

      The return value is an instance of a cgGoogleMapWidget object.

Examples

      Used to put two markers on a map of Fort Collins, Colorado, in a stand-alone window::
          PRO cgGoogleMapWidget_Test
              marker1 = {cgGOOGLEMAPMARKER, 'normal', 'dodger blue', 'A', Ptr_New(40.600), Ptr_New(-105.100)}
              marker2 = {cgGOOGLEMAPMARKER, 'normal', 'purple',      'B', Ptr_New(40.605), Ptr_New(-105.105)}
              googleObject = cgGoogleMapWidget(MARKERS=[marker1, marker2], MAPTYPE='Terrain')
          END

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, 25 June 2012. DWF.

Copyright

      Copyright (c) 2012, Fanning Software Consulting, Inc.