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Last modified: Tue Apr 4 10:50:27 2017.

List of Routines

XCOLORS

Routine Descriptions

XCOLORS

[List of Routines]

NAME:
XCOLORS

PURPOSE:
The purpose of this routine is to interactively change color tables
in a manner similar to XLOADCT. No common blocks are used so
multiple copies of XCOLORS can be on the display at the same
time (if each has a different TITLE). XCOLORS has the ability
to notify a widget event handler, an object method, or an IDL
procedure if and when a new color table has been loaded. The
event handler, object method, or IDL procedure is then responsibe
for updating the program's display on 16- or 24-bit display systems.

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

CATEGORY:
Color

CALLING SEQUENCE:
XCOLORS

INPUTS:
None.

KEYWORD PARAMETERS:
BLOCK: If this keyword is set, the program will try to block the
IDL command line. Note that this is only possible if no other
widget program is currently blocking the IDL command line. It
is much more reliable to make XCOLORS a modal widget (see the MODAL
keyword), although this can generally only be done when XCOLORS
is called from another widget program.

BOTTOM: The lowest color index of the colors to be changed.

COLORINFO: This output keyword will return either a pointer to
a color information structure (if the program is called in
a non-modal fashion) or a color information structure (if the program
is called in modal or blocking fashion). The color information
structure is an anonymous structure defined like this:

struct = { R: BytArr(!D.Table_Size), $ ; The current R color vector.
G: BytArr(!D.Table_Size), $ ; The current G color vector.
B: BytArr(!D.Table_Size), $ ; The current B color vector.
NAME: "", $ ; The name of the current color table.
INDEX: 0 } ; The index number of the current color table.

If a pointer to the structure is obtained, you will be responsible
for freeing it to prevent memory leakage:

XColors, ColorInfo=colorInfoPtr
Print, "Color Table Name: ", (*colorInfoPtr).Name
Ptr_Free, colorInfoPtr

Note that that Name field will be "Unknown" and the Index field will
be -1 until a color table is actually selected by the user. You are
responsible for checking this value before you use it.

When called in modal or blocking fashion, you don't have to worry about freeing
the pointer, since no pointer is involved:

XColors, /Block, ColorInfo=colorInfoData
Help, colorInfoData, /Structure
Print, "Color Table Name: ", colorInfoData.Name

DATA: This keyword can be set to any valid IDL variable. If
the variable is defined, the specified object method or notify
procedure will be passed this variable via a DATA keyword. This
keyword is defined primarily so that Notify Procedures are compatible
with the XLOADCT way of passing data. It is not strictly required,
since the _EXTRA keyword inheritance mechanism will allow passing
of *any* keyword parameter defined for the object or procedure that is
to be notified.

DRAG: Set this keyword if you want colors loaded as you drag
the sliders. Default is to update colors only when you release
the sliders.

_EXTRA: This keyword inheritance mechanism will pick up and
pass along to any method or procedure to be notified and keywords
that are defined for that procedure. Note that you should be sure
that keywords are spelled correctly. Any mis-spelled keyword will
be ignored.

FILE: A string variable pointing to a file that holds the
color tables to load. The normal colors1.tbl file is used by default.

GROUP_LEADER: The group leader for this program. When the group
leader is destroyed, this program will be destroyed.

INDEX: The index of the color table to start up. If provided, a color
table of this index number is loaded prior to display. Otherwise,
the current color table is used. Set this keyword if you wish
to have the index number of the event structure correct when
the user CANCELs out of the progam.

MODAL: Set this keyword (along with the GROUP_LEADER keyword) to
make the XCOLORS dialog a modal widget dialog. Note that NO
other events can occur until the XCOLORS program is destroyed
when in modal mode.

NCOLORS: This is the number of colors to load when a color table
is selected.

NOSLIDERS: If this keyword is set, the color stretch and color gamma
sliders are not displayed. This would be appropriate, for example,
for programs that just load pre-defined color tables.

NOTIFYID: A 2-column by n-row array that contains the IDs of widgets
that should be notified when XCOLORS loads a color table. The first
column of the array is the widgets that should be notified. The
second column contains IDs of widgets that are at the top of the
hierarchy in which the corresponding widgets in the first column
are located. (The purpose of the top widget IDs is to make it
possible for the widget in the first column to get the "info"
structure of the widget program.) An XCOLORS_LOAD event will be
sent to the widget identified in the first column. The event
structure is defined like this:

event = {XCOLORS_LOAD, ID:0L, TOP:0L, HANDLER:0L, $
R:BytArr(!D.TABLE_SIZE < 256), G:BytArr(!D.TABLE_SIZE < 256), $
B:BytArr(!D.TABLE_SIZE < 256), INDEX:0, NAME:""}

The ID field will be filled out with NOTIFYID[0, n] and the TOP
field will be filled out with NOTIFYID[1, n]. The R, G, and B
fields will have the current color table vectors, obtained by
exectuing the command TVLCT, r, g, b, /Get. The INDEX field will
have the index number of the just-loaded color table. The name
field will have the name of the currently loaded color table.

Note that XCOLORS can't initially tell *which* color table is
loaded, since it just uses whatever colors are available when it
is called. Thus, it stores a -1 in the INDEX field to indicate
this "default" value. Programs that rely on the INDEX field of
the event structure should normally do nothing if the value is
set to -1. This value is also set to -1 if the user hits the
CANCEL button. (Note the NAME field will initially be "Unknown").

Typically the XCOLORS button will be defined like this:

xcolorsID = Widget_Button(parentID, Value='Load New Color Table...', $
Event_Pro='Program_Change_Colors_Event')

The event handler will be written something like this:

PRO Program_Change_Colors_Event, event

; Handles color table loading events. Allows colors be to changed.

Widget_Control, event.top, Get_UValue=info, /No_Copy
thisEvent = Tag_Names(event, /Structure_Name)
CASE thisEvent OF

'WIDGET_BUTTON': BEGIN

; Color table tool.

XColors, NColors=info.ncolors, Bottom=info.bottom, $
Group_Leader=event.top, NotifyID=[event.id, event.top]
ENDCASE

'XCOLORS_LOAD': BEGIN

; Update the display for 24-bit displays.

Device, Get_Visual_Depth=thisDepth
IF thisDepth GT 8 THEN BEGIN
WSet, info.wid

...Whatever display commands are required go here. For example...

TV, info.image

ENDIF
ENDCASE

ENDCASE

Widget_Control, event.top, Set_UValue=info, /No_Copy
END

NOTIFYOBJ: A vector of structures (or a single structure), with
each element of the vector defined as follows:

struct = {XCOLORS_NOTIFYOBJ, object:Obj_New(), method:''}

where the Object field is an object reference, and the Method field
is the name of the object method that should be called when XCOLORS
loads its color tables.

ainfo = {XCOLORS_NOTIFYOBJ, a, 'Draw'}
binfo = {XCOLORS_NOTIFYOBJ, b, 'Display'}
XColors, NotifyObj=[ainfo, binfo]

Note that the XColors program must be compiled before these structures
are used. Alternatively, you can put this program, named
"xcolors_notifyobj__define.pro" (*three* underscore characters in this
name!) in your PATH:

PRO XCOLORS_NOTIFYOBJ__DEFINE
struct = {XCOLORS_NOTIFYOBJ, OBJECT:Obj_New(), METHOD:''}
END

Or, you can simply define this structure as it is shown here in your code.

"Extra" keywords added to the XCOLORS call are passed along to
the object method, which makes this an alternative way to get information
to your methods. If you expect such keywords, your methods should be defined
with an _Extra keyword.

NOTIFYPRO: The name of a procedure to notify or call when the color
tables are loaded. If the DATA keyword is also defined, it will
be passed to this program via an DATA keyword. But note that *any*
keyword appropriate for the procedure can be used in the call to
XCOLORS. For example, here is a procedure that re-displays and image
in the current graphics window:

PRO REFRESH_IMAGE, Image=image, _Extra=extra, WID=wid
IF N_Elements(wid) NE 0 THEN WSet, wid
TVIMAGE, image, _Extra=extra
END

This program can be invoked with this series of commands:

IDL> Window, /Free
IDL> TVImage, image, Position=[0.2, 0.2, 0.8, 0.8]
IDL> XColors, NotifyPro='Refresh_Image', Image=image, WID=!D.Window

Note that "extra" keywords added to the XCOLORS call are passed along to
your procedure, which makes this an alternative way to get information
to your procedure. If you expect such keywords, your procedure should
be defined with an _Extra keyword as illustrated above.

TITLE: This is the window title. It is "Load Color Tables" by
default. The program is registered with the name 'XCOLORS:' plus
the TITLE string. The "register name" is checked before the widgets
are defined. If a program with that name has already been registered
you cannot register another with that name. This means that you can
have several versions of XCOLORS open simultaneously as long as each
has a unique title or name. For example, like this:

IDL> XColors, NColors=100, Bottom=0, Title='First 100 Colors'
IDL> XColors, NColors=100, Bottom=100, Title='Second 100 Colors'

XOFFSET: This is the X offset of the program on the display. The
program will be placed approximately in the middle of the display
by default.

YOFFSET: This is the Y offset of the program on the display. The
program will be placed approximately in the middle of the display
by default.

COMMON BLOCKS:
None.

SIDE EFFECTS:
Colors are changed. Events are sent to widgets if the NOTIFYID
keyword is used. Object methods are called if the NOTIFYOBJ keyword
is used. This program is a non-blocking widget.

RESTRICTIONS:
None.

EXAMPLE:
To load a color table into 100 colors, starting at color index
50 and send an event to the widget identified at info.drawID
in the widget heirarchy of the top-level base event.top, type:

XCOLORS, NCOLORS=100, BOTTOM=50, NOTIFYID=[info.drawID, event.top]

MODIFICATION HISTORY:
Written by: David W. Fanning, 15 April 97. Extensive modification
of an older XCOLORS program with excellent suggestions for
improvement by Liam Gumley. Now works on 8-bit and 24-bit
systems. Subroutines renamed to avoid ambiguity. Cancel
button restores original color table.
23 April 1997, added color protection for the program. DWF
24 April 1997, fixed a window initialization bug. DWF
18 June 1997, fixed a bug with the color protection handler. DWF
18 June 1997, Turned tracking on for draw widget to fix a bug
in TLB Tracking Events for WindowsNT machines in IDL 5.0. DWF
20 Oct 1997, Changed GROUP keyword to GROUP_LEADER. DWF
19 Dec 1997, Fixed bug with TOP/BOTTOM reversals and CANCEL. DWF.
9 Jun 1998, Fixed bug when using BOTTOM keyword on 24-bit devices. DWF
9 Jun 1998, Added Device, Decomposed=0 for TrueColor visual classes. DWF
9 Jun 1998, Removed all IDL 4 compatibility.
21 Oct 1998, Fixed problem with gamma not being reset on CANCEL. DWF
5 Nov 1998. Added the NotifyObj keyword, so that XCOLORS would work
interactively with objects. DWF.
9 Nov 1998. Made slider reporting only at the end of the drag. If you
want continuous updating, set the DRAG keyword. DWF.
9 Nov 1998. Fixed problem with TOP and BOTTOM sliders not being reset
on CANCEL. DWF.
10 Nov 1998. Fixed fixes. Sigh... DWF.
5 Dec 1998. Added INDEX field to the XCOLORS_LOAD event structure. This
field holds the current color table index number. DWF.
5 Dec 1998. Modified the way the colorbar image was created. Results in
greatly improved display for low number of colors. DWF.
6 Dec 1998. Added the ability to notify an unlimited number of objects. DWF.
12 Dec 1998. Removed obsolete Just_Reg keyword and improved documetation. DWF.
30 Dec 1998. Fixed the way the color table index was working. DWF.
4 Jan 1999. Added slightly modified CONGRID program to fix floating divide
by zero problem. DWF
2 May 1999. Added code to work around a Macintosh bug in IDL through version
5.2 that tries to redraw the graphics window after a TVLCT command. DWF.
5 May 1999. Restore the current window index number after drawing graphics.
Not supported on Macs. DWF.
9 Jul 1999. Fixed a couple of bugs I introduced with the 5 May changes. Sigh... DWF.
13 Jul 1999. Scheesh! That May 5th change was a BAD idea! Fixed more bugs. DWF.
31 Jul 1999. Substituted !D.Table_Size for !D.N_Colors. DWF.
1 Sep 1999. Got rid of the May 5th fixes and replaced with something MUCH simpler. DWF.
14 Feb 2000. Removed the window index field from the object notify structure. DWF.
14 Feb 2000. Added NOTIFYPRO, DATA, and _EXTRA keywords. DWF.
20 Mar 2000. Added MODAL, BLOCK, and COLORINFO keywords. DWF
20 Mar 2000. Fixed a slight problem with color protection events triggering
notification events. DWF.
31 Mar 2000. Fixed a problem with pointer leakage on Cancel events, and improved
program documentation. DWF.
17 Aug 2000. Fixed a problem with CANCEL that occurred only if you first
changed the gamma settings before loading a color table. DWF.
10 Sep 2000. Removed the requirement that procedures and object methods must
be written with an _Extra keyword. DWF.
5 Oct 2000. Added the File keyword to LOADCT command, as I was suppose to. DWF.
5 Oct 2000. Now properly freeing program pointers upon early exit from program. DWF.
7 Mar 2001. Fixed a problem with the BLOCK keyword. DWF.
12 Nov 2001. Renamed Congrid to XColors_Congrid. DWF.
14 Aug 2002. Moved the calculation of NCOLORS to after the draw widget creation
to fix a problem with !D.TABLE_SIZE having a correct value when no windows had
been opened in the current IDL session. DWF.
14 Aug 2002. Fixed a documentation problem in the NOTIFYID keyword documentation
that still referred to !D.N_COLORS instead of the current !D.TABLE_SIZE. DWF.
27 Oct 2003. Added INDEX keyword. DWF.
29 July 2004. Fixed a problem with freeing colorInfoPtr if it didn't exist. DWF.
5 December 2005. Added NOSLIDERS keyword and performed some small cosmetic changes. DWF.
27 Sep 2006. Fixed a problem in which XCOLORS set device to indexed color mode. DWF.
bmy, 21 Apr 2008: GAMAP VERSION 2.12
- Added XCOLORS into GAMAP v2-12 unmodified,
except for minor comment header changes, e.g.:
* added ID tag for CVS repository
* also changed category to "Color" for
compatibility w/ GAMAP documentation

(See /n/home09/ryantosca/IDL/gamap2/color/xcolors.pro)