WIDGET CLASS NAME

Slider

SYNOPSIS

#include <Intrinsic.h>
#include <StringDefs.h>
#include <OpenLook.h>
#include <Slider.h>
widget = XtCreateWidget(name, sliderWidgetClass, ...)

DESCRIPTION

Slider Components The Slider widget implements a simple control used to change a numeric value. It consists of the following elements:

     - Top (Left) Anchor

     - Bottom (Right) Anchor

     - Drag Box

     - Bar (typically)

     - Shaded Bar (typically)

     - Current Value (not visible)

     - Minimum Value (not visible)

     - Maximum Value (not  visible)  The  Current  Value  is  the
       numeric  value  a  user attempts to change with the Slider
       widget.

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                      Figure 1.  Horizontal Slider
                      Figure 2.  Vertical Slider

Drag Box Motion As visual feedback to the user, the Drag Box moves up or down (or left or right) along the Bar as the Current Value changes.

Dragging SELECT The user can change the Current Value by dragging the Drag Box with SELECT. The pressing of SELECT must start with the pointer in the Drag Box, but the Drag Box (and the Current Value) track the pointer motion regardless of where it goes while SELECT is pressed. This means it is not possible for the user to change the Current Value by first pressing SELECT outside the Drag Box and then moving the pointer into it. Only the component of the pointer motion parallel to the Bar is tracked, and the motion of the Drag Box (and change in the Current Value) are limited by the length of the Bar.

Clicking SELECT Clicking SELECT above the Drag Box for a vertical slider, or to the right for a horizontal slider, increases the Current Value by an application-specified amount, moves the Drag Box to correspond to the new Current Value, and moves the pointer to keep it on the Drag Box. Clicking SELECT to the other side of the Drag Box decreases the value by the same amount and moves the Drag Box and pointer accordingly. Pressing SELECT repeats this action.

Moving Drag Box to Limits Clicking SELECT on one of the Bottom/Left or Top/Right Anchors causes the Current Value to take on the Minimum Value or Maximum Value, respectively, and moves the Drag Box to the limit in the direction of the Anchor. If the Drag Box is already at the limit, nothing happens. Clicking SELECT on an Anchor highlights the Anchor while the Current Value is changed.

Application Notification The application finds out about a change in the Current Value on the release of SELECT for either the drag or click. It is responsible for providing any feedback to the end user deemed appropriate, such as updating the Current Value in a text field.

Slider Coloration Figure 3 illustrates the resources that affect the coloration of the Slider widget.

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                      Figure 3.  Slider Coloration

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RESOURCES

     ______________________________________________________________________________________
     ______________________________Slider_Resource_Set\*(cO________________________________
      Name                   Class                  Type             Default        Access
     ______________________________________________________________________________________

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     ______________________________________________________________________________________
     _XtNancestorSensitive___XtCSenstitive__________Boolean__________TRUE___________G*_____
    | XtNbackground          XtCBackground          Pixel            White          SGI-  |
    |_____________________|______________________|________________|______________|________|
    |_XtNbackgroundPixmap_|__XtCPixmap___________|__Pixmap________|__(none)______|__SGI-__|
    | XtNdepth            |  XtCDepth            |  int           |  (parent's)  |  GI    |
    |_____________________|______________________|________________|______________|________|
    |_XtNdestroyCallback__|__XtCCallback_________|__XtCallbackList|__NULL________|__SI____|
    | XtNforeground       |  XtCForeground       |  Pixel         |  Black       |  SGI-  |
    |_____________________|______________________|________________|______________|________|
    |_XtNgranularity______|__XtCGranularity______|__int___________|__1___________|__SGI___|
    | XtNheight           |  XtCHeight           |  Dimension     |  (calculated)|  SGI   |
    |_____________________|______________________|________________|______________|________|
    |_XtNinitialDelay_____|__XtCInitialDelay_____|__int___________|__500_________|__SGI___|
    | XtNmappedWhenManaged|  XtCMappedWhenManaged|  Boolean       |  TRUE        |  SGI   |
    |_____________________|______________________|________________|______________|________|
    |_XtNorientation______|__XtCOrientation______|__OlDefine______|__OL_VERTICAL_|__I_____|
    | XtNrepeatRate       |  XtCRepeatRate       |  int           |  100         |  SGI   |
    |_____________________|______________________|________________|______________|________|
    |_XtNsensitive________|__XtCSensitive________|__Boolean_______|__TRUE________|__GI*___|
    | XtNsliderMax        |  XtCSliderMax        |  int           |  100         |  SGI   |
    |_____________________|______________________|________________|______________|________|
    |_XtNsliderMin________|__XtCSliderMax________|__int___________|__0___________|__SGI___|
    | XtNsliderMoved      |  XtCCallback         |  XtCallbackList|  NULL        |  SI    |
    |_____________________|______________________|________________|______________|________|
    |_XtNsliderValue______|__XtCSliderValue______|__int___________|__0___________|__SGI___|
    | XtNuserData         |  XtCUserData         |  XtPointer     |  NULL        |  SGI   |
    |_____________________|______________________|________________|______________|________|
    |_XtNwidth____________|__XtCWidth____________|__Dimension_____|__(calculated)|__SGI___|
    | XtNx                |  XtCPosition         |  Position      |  0           |  SGI   |
    |_____________________|______________________|________________|______________|________|
    |_XtNy________________|__XtCPosition_________|__Position______|__0___________|__SGI___|
     XtNforeground This resource defines the foreground color for
     the  widget.   See  the  note  about the interaction of this
     resource with other color resources under the description of
     the XtNbackground resource in CORE(3W).

     XtNgranularity

     Range of Values:

          1 < XtNgranularity < (XtNsliderMax - XtNsliderMin)

Clicking SELECT on the Bar or Shaded Bar attempts to change the Current Value by the amount given in this resource. Dragging the Drag Box with SELECT changes the Current Value by this amount before the XtNsliderMoved callbacks are issued.

     XtNinitialDelay

     Range of Values:

          0 < XtNinitialDelay

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This resource gives the time, in milliseconds, before the first action occurs when SELECT is pressed on the Bar or Shaded Bar. Note that millisecond timing precision may not be possible for all implementations, so the value may be rounded up to the nearest available unit by the toolkit.

XtNorientation

Range of Values:
     OL_HORIZONTAL/"horizontal"
     OL_VERTICAL/"vertical"

This resource defines the direction for the visual presentation of the widget.

     XtNrepeatRate

     Range of Values:

          0 < XtNrepeatRate

     This resource  gives  the  time,  in  milliseconds,  between
     repeated actions when SELECT is pressed on the Bar or Shaded
     Bar.  Note that millisecond timing precision may not be pos-
     sible  for  all implementations, so the value may be rounded
     up to the nearest available unit by the toolkit.
     XtNsliderMax
     XtNsliderMin

     Range of Values:

          XtNsliderMin < XtNsliderMax

     These two resources give the range of values tracked by  the
     Slider  widget.   Mathematically,  the  range is open on the
     right; that is, the range is the following subset of the set
     of integers:
                 XtNsliderMin < range < XtNsliderMax
     This is independent of the Drag Box displayed in the  Slider
     widget.   The  Slider  widget is responsible for taking into
     account the size of the Drag Box when relating the  physical
     range of movement to the range of values.

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                Figure 4.  Drag Box Range of Movement

XtNsliderMoved This resource defines the callback list used when the Slider widget is manipulated. The call_data parameter is a pointer to the Current Value; an XtGetValue() inside the callback will return the previous value.

     XtNsliderValue Range of Values:
          XtNsliderMin < XtNsliderValue < XtNsliderMax
     This resource gives the current position of the Drag Box, in
     the  range  [  XtNsliderMin  ,  XtNsliderMax  ].  The Slider
     widget keeps this resource up to date; however, an  applica-
     tion  can  also get the current value through the XtNslider-
     Moved callbacks.

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