cgblendimage.pro
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; docformat = 'rst'
;
; NAME:
; cgBlendImage
;
; PURPOSE:
; This alpha blends two 24-bit images and displays them with the cgImage command.
;
;******************************************************************************************;
; ;
; Copyright (c) 2011, by Fanning Software Consulting, Inc. All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
;
;+
; This alpha blends two 24-bit images and displays them with the cgImage command.
;
; The program requires the `Coyote Library <http://www.idlcoyote.com/documents/programs.php>`
; to be installed on your machine.
;
; :Categories:
; Graphics
;
; :Params:
; foregroundImage: in, required, type=truecolor
; A 24-bit foreground image with the same dimensions as the background image.
; backgroundImage: in, required, type=truecolor
; A 24-bit background image with the same dimensions as the foreground image.
;
; :Keywords:
; alpha: in, optional, type=float, default=0.5
; A number between 0 and 1 that indicates the percentage of the foreground image
; to alpha-blend into the background image. For example, ALPHA=0.2 will give
; a weigth of 20% to the foreground image pixels and 80% to the background image
; pixels.
; window: in, optional, type=intarr
; A one-, two-, or three-element array giving the window index numbers for
; the foreground, background, and display windows, repectively. If one-element,
; the foreground image is retrieved from that window and displayed in the current
; window. If two elements, the foreground and background images are obtained from
; the first two elements, respectively, and a new third display window is opened.
; This is the same for three elements, except the third element is used to specify
; the display window.
; _ref_extra: in, optional
; Any keyword appropriate for the cgImage command is also accepted by keyword
; inheritance.
;
; :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 by: David W. Fanning, 26 May 2009.
; Added the WINDOW keyword. 16 February 2012. DWF.
;
; :Copyright:
; Copyright (c) 2009-2012, Fanning Software Consulting, Inc.
;-
PRO cgBlendImage, foreGroundImage, backGroundImage, $
ALPHA=alpha, $
WINDOW=window, $
_REF_EXTRA=extra
; Error handling.
Catch, theError
IF theError NE 0 THEN BEGIN
void = cgErrorMsg()
RETURN
ENDIF
; Handle the window keyword
IF N_Elements(window) NE 0 THEN BEGIN
; Save the current graphics window. Be aware that this may be -1.
thisWindow = !D.Window
; How many elements are in the WINDOW keyword?
CASE N_Elements(window) OF
1: BEGIN
WSet, window[0]
foreGroundImage = cgSnapshot()
IF thisWindow GE 0 THEN BEGIN
WSet, thisWindow
ENDIF ELSE BEGIN
cgDisplay, /Force, /Match, /Free
ENDELSE
backGroundImage = cgSnapshot()
END
2: BEGIN
WSet, window[0]
foreGroundImage = cgSnapshot()
WSet, window[1]
backGroundImage = cgSnapshot()
cgDisplay, /Force, /Match, /Free
END
3: BEGIN
WSet, window[0]
foreGroundImage = cgSnapshot()
WSet, window[1]
backGroundImage = cgSnapshot()
IF WindowAvailable(window[2]) THEN BEGIN
WSet, window[2]
ENDIF ELSE BEGIN
cgDisplay, /Force, /Match, /Free
ENDELSE
END
ELSE: Message, 'WINDOW keyword must contain no more than three elements.'
ENDCASE
ENDIF
; Need a foreground and a background image.
IF (N_Elements(foregroundImage) EQ 0) || (N_Elements(backgroundImage) EQ 0) $
THEN Message, 'Usage: "BlendedImage, foreGroundImage, backGroundImage"'
; Condition alpha blending value.
IF N_Elements(alpha) EQ 0 THEN alpha = 0.5
alpha = 0.0 > alpha < 1.0
; Do input image dimensions match?
IF Total( Size(foregroundImage, /DIMENSIONS) EQ Size(backgroundImage, /DIMENSIONS) ) NE 3 $
THEN Message, 'Dimensions and/or size of input images do not match.'
; Output the blended image.
cgImage, (foreGroundImage * alpha) + (1 - alpha) * backGroundImage, _STRICT_EXTRA=extra
END