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MGH_CW_PALETTE_EDITOR

MGH_CW_PALETTE_EDITOR

Name


  MGH_CW_PALETTE_EDITOR

Purpose


  MGH_CW_PALETTE_EDITOR is a compound widget for the modification of color
      palette vectors.

Category


  Compound Widgets

Calling Sequence


  Widget = MGH_CW_PALETTE_EDITOR(Parent)

Inputs


  Parent: ID of the parent widget.

Keyword Parameters


  DATA: A 3x256 byte array containing the initial color values
                for Red, Green and Blue channels. The value supplied
                can also be a 4x256 byte array containing the initial
                color values and the optional Alpha channel. The value
                supplied can also be an IDLgrPalette object reference.
                If an IDLgrPalette object reference is supplied it is
                used internally and is not destroyed on exit. If an
                object reference is supplied the ALPHA keyword to the
                MGH_CW_PALETTE_EDITOR_SET routine can be used to supply
                the data for the optional Alpha channel.
  FILE: Set this keyword to a string representing the name
                of the color table file from which the predefined colors
                will be read. The default is the IDL system
                color table file, <IDL_DIR>/resource/colors/colors1.tbl.
  FRAME: If set, a frame will be drawn around the widget.
  HISTOGRAM: A 256 element byte vector containing the values for
                the optional histogram curve.
  HORIZONTAL: Set this keyword for a horizontal layout for the
                compound widget. This consists of the controls
                to the right of the display area. The default
                is a vertical layout with the controls below the
                display area.
  SELECTION: A two element vector defining the starting and ending
                point of the selection region. The default is [0,255].
  UNAME: Set this keyword to a string that can be used to identify
                the widget. You can associate a name with each widget in
                a specific hierarchy, and then use that name to query the
                widget hierarchy and get the correct widget ID.
                To query the widget hierarchy, use the WIDGET_INFO function
                with the FIND_BY_UNAME keyword. The UNAME should be unique
                to the widget hierarchy because the FIND_BY_UNAME keyword
                returns the ID of the first widget with the specified name.
  UVALUE: The "user value" to be assigned to the widget. Each widget
                can contain a user-specified value of any data type and
                organization. This value is not used by the widget in any
                way, but exists entirely for the convenience of the IDL
                programmer. This keyword allows you to set this value when
                the widget is first created. If UVALUE is not present, the
                widget's initial user value is undefined.
  XSIZE: The width of the drawable area in pixels. The default width
                is 256.
  YSIZE: The height of the drawable area in pixels. The default
                height is 256.

Outputs


  The ID of the created widget is returned.

Procedure


  Standard Compound widget. Use WIDGET_CONTROL, SET_VALUE and GET_VALUE
  to change/read the widget's value. The value supplied to the SET_VALUE
  keyword can be any of the three types described by the DATA keyword.
  The value returned by the GET_VALUE keyword is a 3x256 or 4x256 array
  containing the color vectors and the optional alpha channel if it is
  in use.

Side Effects


  Palette Editor Events:
  This widget generates several types of event structures. There are
  variations of the palette editor event structure depending on the
  specific event being reported. All of these structures contain the
  standard three fields (ID, TOP, and HANDLER).
  The different palette editor event structures are described below.
  Selection Moved
  This is the type of structure returned when one of the drag handles
  that define the selection region is moved by a user.
  event = { MGH_CW_PALETTE_EDITOR_SM, $
      ID: state.wCWPalEdTop, $
      TOP: wAppTop, $
      HANDLER: handler, $
      SELECTION: [state.sel_x1, state.sel_x2] $
  }
  SELECTION indicates a two element vector defining the starting and
  ending point of the selection region of color indexes.
  Palette Edited
  This is the type of structure returned when the user has modified the
  color palette.
  event = { MGH_CW_PALETTE_EDITOR_PM, $
      ID: state.wCWPalEdTop, $
      TOP: wAppTop, $
      HANDLER: handler $
  }
  The value of the palette editor will need to be retrieved (i.e.,
  WIDGET_CONTROL, GET_VALUE) in order to determine the extent of the
  actual user modification.
  UTILITY ROUTINES
  MGH_CW_PALETTE_EDITOR_GET: Get palette editor compound widget properties.

Calling Sequence


  MGH_CW_PALETTE_EDITOR_GET, widgetID

Inputs


  widgetID: The widget ID of the MGH_CW_PALETTE_EDITOR compound widget.

Keyword Parameters


  ALPHA: A 256 element byte array containing the Alpha channel.
  FILE: A string containing the path name of the color-table file.
  HISTOGRAM: A 256 element byte array containing the histogram curve.
  MGH_CW_PALETTE_EDITOR_SET: Set palette editor compound widget properties.

Calling Sequence


  MGH_CW_PALETTE_EDITOR_SET, widgetID

Inputs


  widgetID: The widget ID of the MGH_CW_PALETTE_EDITOR compound widget.

Keyword Parameters


  ALPHA: A 256 element byte array containing the Alpha channel
                or the scalar value zero to remove the alpha curve
                from the display.
  FILE: A string containing the path name of the color-table file.
  HISTOGRAM: A 256 element byte array containing the histogram curve
                or the scalar value zero to remove the histogram from
                the display.

Example


  A = WIDGET_BASE(TITLE='Example', /COLUMN)
  B = MGH_CW_PALETTE_EDITOR(A, ....

Modification History


  ACY, April, 1999. Written.



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