XmScale(3)

NAME
XmScale — The Scale widget class

SYNOPSIS

#include <Xm/Scale.h>

DESCRIPTION

Scale is used by an application to indicate a value from within a range of values, and it allows the user to input or modify a value from the same range.

A Scale has an elongated rectangular region similar to a ScrollBar. A slider inside this region indicates the current value along the Scale. The user can also modify the Scale's value by moving the slider within the rectangular region of the Scale. A Scale can also include a label set located outside the Scale region. These can indicate the relative value at various positions along the scale. The placement of this label depends on the XmNlayoutDirection resource of the widget.

A Scale can be either input/output or output only. An input/output Scale's value can be set by the application and also modified by the user with the slider. An output-only Scale is used strictly as an indicator of the current value of something and cannot be modified interactively by the user. The XmScale resource XmNeditable specifies whether the user can interactively modify the Scale's value.

The user can specify resources in a resource file for the automatically created gadget that contains the title of the Scale widget. The name of the gadget is Title. The placement of the title depends on the XmNlayoutDirection resource of the widget. The direction of the title is based on the widget's layout direction.

Scale uses the XmQTspecifyRenderTable trait, and holds the XmQTtransfer trait.

  Data Transfer Behavior

Scale supports dragging of the representation of the Scale value from the Scale when the value is displayed and when the value of the XmNenableUnselectableDrag resource of XmDisplay is set to True.

As a source of data, Scale supports the following targets and associated conversions of data to these targets:

COMPOUND_TEXT
    The widget transfers a string representation of XmNvalue as type COMPOUND_TEXT.

UTF8_STRING
    The widget transfers a string representation of XmNvalue as type UTF8_STRING.

STRING
    The widget transfers a string representation of XmNvalue as type STRING.

_MOTIF_CLIPBOARD_TARGETS
    The widget transfers, as type ATOM, a list of the targets it supports for the CLIPBOARD selection. These include STRING, COMPOUND_TEXT and UTF8_STRING.

_MOTIF_EXPORT_TARGETS
    The widget transfers, as type ATOM, a list of the targets to be used as the value of the DragContext's XmNexportTargets in a drag-and-drop transfer. These include STRING, COMPOUND_TEXT and UTF8_STRING.

As a source of data, Scale also supports the following standard Motif targets:

BACKGROUND
    The widget transfers XmNbackground as type PIXEL.

CLASS
    The widget finds the first shell in the widget hierarchy that has a WM_CLASS property and transfers the contents as text in the current locale.

CLIENT_WINDOW
    The widget finds the first shell in the widget hierarchy and transfers its window as type WINDOW.

COLORMAP
    The widget transfers XmNcolormap as type COLORMAP.

FOREGROUND
    The widget transfers XmNforeground as type PIXEL.

NAME
    The widget finds the first shell in the widget hierarchy that has a WM_NAME property and transfers the contents as text in the current locale.

TARGETS
    The widget transfers, as type ATOM, a list of the targets it supports. These include the standard targets in this list. These also include STRING, COMPOUND_TEXT and UTF8_STRING.

TIMESTAMP
    The widget transfers the timestamp used to acquire the selection as type INTEGER.

_MOTIF_RENDER_TABLE
    The widget transfers XmNrenderTable if it exists, or else the default text render table, as type STRING.

_MOTIF_ENCODING_REGISTRY
    The widget transfers its encoding registry as type STRING. The value is a list of NULL separated items in the form of tag encoding pairs. This target symbolizes the transfer target for the Motif Segment Encoding Registry. Widgets and applications can use this Registry to register text encoding formats for specified render table tags. Applications access this Registry by calling XmRegisterSegmentEncoding and XmMapSegmentEncoding.

  Descendants

Scale automatically creates the descendants shown in the following table. An application can use XtNameToWidget to gain access to the named descendant. In addition, a user or an application can use the named descendant when specifying resource values.

  Classes

Scale inherits behavior, resources, and traits from Core, Composite, Constraint, and XmManager classes.

The class pointer is xmScaleWidgetClass.

The class name is XmScale.

  New Resources

The following table defines a set of widget resources used by the programmer to specify data. The programmer can also set the resource values for the inherited classes to set attributes for this widget. To reference a resource by name or by class in a .Xdefaults file, remove the XmN or XmC prefix and use the remaining letters. To specify one of the defined values for a resource in a .Xdefaults file, remove the Xm prefix and use the remaining letters (in either lowercase or uppercase, but include any underscores between words). The codes in the access column indicate if the given resource can be set at creation time (C), set by using XtSetValues (S), retrieved by using XtGetValues (G), or is not applicable (N/A).

XmNconvertCallback
    Specifies a list of callbacks called when the Scale is asked to convert a selection. The type of the structure whose address is passed to these callbacks is XmConvertCallbackStruct. The reason is XmCR_OK.

XmNdecimalPoints
    Specifies the number of decimal points to shift the slider value when displaying it. For example, a slider value of 2,350 and an XmdecimalPoints value of 2 results in a display value of 23.50. The value must not be negative.

XmNdragCallback
    Specifies the list of callbacks that is called when the slider position changes as the slider is being dragged. The reason sent by the callback is XmCR_DRAG.

XmNeditable
    Specifies how the Scale scrollbar will react to user input. This resource can be True or False values, as follows:

    True
        Allows the scrollbar to be sensitive to user input. This is the default value.

    False
        Makes the Scale scrollbar insensitive to user input. The visual is not greyed out. This value would mostly be used in XmTHERMOMETER mode.

    When XmNeditable is used on a widget it sets the dropsite to XmDROP_SITE_ACTIVE.

XmNfontList
    Specifies the font list to use for the title text string specified by XmNtitleString, and the label displayed when XmNshowValue is True. The font list is an obsolete structure, and is retained only for compatibility with earlier releases of Motif. See the XmNrenderTable resource.

XmNhighlightOnEnter
    Specifies whether the highlighting rectangle is drawn when the cursor moves into the widget. If the shell's focus policy is XmEXPLICIT, this resource is ignored, and the widget is highlighted when it has the focus. If the shell's focus policy is XmPOINTER and if this resource is True, the highlighting rectangle is drawn when the the cursor moves into the widget. If the shell's focus policy is XmPOINTER and if this resource is False, the highlighting rectangle is not drawn when the the cursor moves into the widget. The default is False.

XmNhighlightThickness
    Specifies the size of the slider's border drawing rectangle used for enter window and traversal highlight drawing.

XmNmaximum
    Specifies the slider's maximum value. XmNmaximum must be greater than XmNminimum.

XmNminimum
    Specifies the slider's minimum value. XmNmaximum must be greater than XmNminimum.

XmNorientation
    Displays Scale vertically or horizontally. This resource can have values of XmVERTICAL and XmHORIZONTAL.

XmNprocessingDirection
    Specifies whether the value for XmNmaximum is on the right or left side of XmNminimum for horizontal Scales or above or below XmNminimum for vertical Scales. This resource can have values of XmMAX_ON_TOP, XmMAX_ON_BOTTOM, XmMAX_ON_LEFT, and XmMAX_ON_RIGHT. If the Scale is oriented vertically, the default value is XmMAX_ON_TOP. If the XmScale is oriented horizontally, the default value depends on the XmNlayoutDirection resource of the widget.

XmNrenderTable
    Specifies the render table to use for the title text string specified by XmNtitleString, and the label displayed when XmNshowValue is True. If this value is NULL at initialization, the parent hierarchy is searched for an ancestor that holds the XmQTspecifyRenderTable trait. If such an ancestor is found, the render table is initialized to the XmLABEL_RENDER_TABLE value of the ancestor widget. If no such ancestor is found, the default is implementation dependent. If a font list (XmNfontList) and a render table are both specified, the render table will take precedence. Refer to XmRenderTable(3) for more information on the creation and structure of a render table.

XmNscaleHeight
    Specifies the height of the slider area. The value should be in the specified unit type (the default is pixels). If no value is specified a default height is computed.

XmNscaleMultiple
    Specifies the amount to move the slider when the user takes an action that moves the slider by a multiple increment. The default is (XmNmaximum - XmNminimum) divided by 10, with a minimum of 1.

XmNscaleWidth
    Specifies the width of the slider area. The value should be in the specified unit type (the default is pixels). If no value is specified a default width is computed.

XmNshowArrows
    Specifies whether the arrows are displayed and how they are to be displayed. This resource can take the following values:

    XmEACH_SIDE
        Indicates that one arrow is displayed on each end of the ScrollBar slider.

    XmMAX_SIDE
        Indicates that one arrow is displayed on the XmNmaximum side of the ScrollBar slider.

    XmMIN_SIDE
        Indicates that one arrow is displayed on the XmNminimum side of the ScrollBar slider.

    XmNONE
        Indicates that no arrows are displayed.

    XmNONE is the default value.

XmNshowValue
    Specifies whether a label for the current slider value should be displayed next to the slider. If the value is XmNEAR_SLIDER, the current slider value is displayed. If the value is XmNONE, no slider value is displayed. If the value is XmNEAR_BORDER, the current slider value is displayed near the border.

XmNsliderMark
    Specifies the shape the slider is to be displayed in. This resource can take the following values:

    XmETCHED_LINE
        Specifies the slider as an etched line. This is the default when XmNslidingMode is XmSLIDER.

    XmNONE
        Specifies the slider as a foregrounded rectangle. This is the default when XmNslidingMode is XmTHERMOMETER and the Scale scrollbar is insensitive to user input (XmNeditable is False.

    XmROUND_MARK
        Specifies the slider as a shadowed circle. This is the default when XmNslidingMode is XmTHERMOMETER and the Scale scrollbar is sensitive to user input (XmNeditable is True.

    XmTHUMB_MARK
        Specifies the slider as a series of three etched lines centered in the middle of the slider.

XmNslidingMode
    Specifies the mode the slider works in. There are two possible modes:

    XmSLIDER
        Allows the slider to move freely between the minimum and maximum ends of the scale. This is the default value.

    XmTHERMOMETER
        Forces the slider to be anchored to one side of the trough area.

XmNsliderVisual
    Specifies the color of the slider visual. This resource can take the following values:

    XmBACKGROUND_COLOR
        Specifies that the slider visual is in the background color.

    XmFOREGROUND_COLOR
        Specifies that the slider visual is in the foreground color.

    XmSHADOWED_BACKGROUND
        Specifies that the slider visual is in the background color, with a shadow. This is the default when the XmNslidingModel resource is XmSLIDER.

    XmTROUGH_COLOR
        Specifies that the slider visual is in the trough color. This is the default when the XmNslidingModel resource is XmTHERMOMETER.

XmNtitleString
    Specifies the title text string to appear in the Scale widget window.

XmNvalue
    Specifies the slider's current position along the scale, between XmNminimum and XmNmaximum. The value is constrained to be within these inclusive bounds. The initial value of this resource is the larger of 0 (zero) and XmNminimum.

XmNvalueChangedCallback
    Specifies the list of callbacks that is called when the value of the slider has changed. The reason sent by the callback is XmCR_VALUE_CHANGED.

  Inherited Resources

Scale inherits behavior and resources from the superclasses described in the following tables. For a complete description of each resource, refer to the reference page for that superclass.

  Callback Information

A pointer to the following structure is passed to the XmNdragCallback and XmNvalueChangedCallback procedures:

typedef struct
{
        int reason;
        XEvent * event;
        int value;
} XmScaleCallbackStruct;

reason
    Indicates why the callback was invoked

event
    Points to the XEvent that triggered the callback

value
    Is the new slider value

A pointer to the following structure is passed to the XmNconvertCallback procedures:

typedef struct
{
        int reason;
        XEvent *event;
        Atom selection;
        Atom target;
        XtPointer source_data;
        XtPointer location_data;
        int flags;
        XtPointer parm;
        int parm_format;
        unsigned long parm_length;
        int status;
        XtPointer value;
        Atom type;
        int format;
        unsigned long length;
} XmConvertCallbackStruct;

reason
    Indicates why the callback was invoked.

event
    Points to the XEvent that triggered the callback. It can be NULL.

selection
    Indicates the selection for which conversion is being requested. Possible values are CLIPBOARD, PRIMARY, SECONDARY, and _MOTIF_DROP.

target
    Indicates the conversion target.

source_data
    Contains information about the selection source. When the selection is _MOTIF_DROP, source_data is the DragContext. Otherwise, it is NULL.

location_data
    Contains information about the location of data to be converted. If the value is NULL, the data to be transferred consists of the widget's current selection.

flags
    Indicates the status of the conversion. Following are the possible values:

    XmCONVERTING_NONE
        This flag is currently unused.

    XmCONVERTING_PARTIAL
        The target widget was able to be converted, but some data was lost.

    XmCONVERTING_SAME
        The conversion target is the source of the data to be transferred.

    XmCONVERTING_TRANSACT
        This flag is currently unused.

parm
    Contains parameter data for this target. If no parameter data exists, the value is NULL.

    When selection is CLIPBOARD and target is _MOTIF_CLIPBOARD_TARGETS or _MOTIF_DEFERRED_CLIPBOARD_TARGETS, the value is the requested operation (XmCOPY, XmMOVE, or XmLINK).

parm_format
    Specifies whether the data in parm should be viewed as a list of char, short, or long quantities. Possible values are 0 (when parm is NULL), 8 (when the data in parm should be viewed as a list of chars), 16 (when the data in parm should be viewed as a list of shorts), or 32 (when the data in parm should be viewed as a list of longs). Note that parm_format symbolizes a data type, not the number of bits in each list element. For example, on some machines, a parm_format of 32 means that the data in parm should be viewed as a list of 64-bit quantities, not 32-bit quantities.

parm_length
    Specifies the number of elements of data in parm, where each element has the size specified by parm_format. When parm is NULL, the value is 0.

status
    An IN/OUT member that specifies the status of the conversion. The initial value is XmCONVERT_DEFAULT. The callback procedure can set this member to one of the following values:

    XmCONVERT_DEFAULT
        This value means that the widget class conversion procedure, if any, is called after the callback procedures return. If the widget class conversion procedure produces any data, it overwrites the data provided by the callback procedures in the value member.

    XmCONVERT_MERGE
        This value means that the widget class conversion procedure, if any, is called after the callback procedures return. If the widget class conversion procedure produces any data, it appends its data to the data provided by the callback procedures in the value member. This value is intended for use with targets that result in lists of data, such as TARGETS.

    XmCONVERT_DONE
        This value means that the callback procedure has successfully finished the conversion. The widget class conversion procedure, if any, is not called after the callback procedures return.

    XmCONVERT_REFUSE
        This value means that the callback procedure has terminated the conversion process without completing the requested conversion. The widget class conversion procedure, if any, is not called after the callback procedures return.

value
    An IN/OUT parameter that contains any data that the callback procedure produces as a result of the conversion. The initial value is NULL. If the callback procedure sets this member, it must ensure that the type, format, and length members correspond to the data in value. The callback procedure is responsible for allocating, but not for freeing, memory when it sets this member.

type
    An IN/OUT parameter that indicates the type of the data in the value member. The initial value is INTEGER.

format
    An IN/OUT parameter that specifies whether the data in value should be viewed as a list of char, short, or long quantities. The initial value is 8. The callback procedure can set this member to 8 (for a list of char), 16 (for a list of short), or 32 (for a list of long).

length
    An IN/OUT member that specifies the number of elements of data in value, where each element has the size symbolized by format. The initial value is 0.

  Behavior

XmScale has the following behavior:

<Btn1Down> or <Btn2Down>:
    In the region between an end of the Scale and the slider: Moves the slider by one multiple increment in the direction of the end of the Scale and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_RIGHT or XmMAX_ON_BOTTOM, movement toward the right or bottom increments the Scale value, and movement toward the left or top decrements the Scale value. If XmNprocessingDirection is XmMAX_ON_LEFT or XmMAX_ON_TOP, movement toward the right or bottom decrements the Scale value, and movement toward the left or top increments the Scale value. If the button is held down longer than a delay period, the slider is moved again by the same increment and the same callbacks are called.

    In slider: Activates the interactive dragging of the slider.

<Btn2Down> in value label:
    Drags the contents of the label showing the current slider value. This action sets the XmNconvertProc of the DragContext to a function that calls the XmNconvertCallback procedures, possibly multiple times, for the _MOTIF_DROP selection.

<Btn1Motion> or <Btn2Motion>:
    If the button press occurs within the slider, the subsequent motion events move the slider to the position of the pointer and call the callbacks for XmNdragCallback.

<Btn1Up> or <Btn2Up>:
    If the button press occurs within the slider and the slider position is changed, the callbacks for XmNvalueChangedCallback are called.

<Ctrl><Btn1Down>:
    In the region between an end of the Scale and the slider: Moves the slider to that end of the Scale and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_RIGHT or XmMAX_ON_BOTTOM, movement toward the right or bottom increments the Scale value, and movement toward the left or top decrements the Scale value. If XmNprocessingDirection is XmMAX_ON_LEFT or XmMAX_ON_TOP, movement toward the right or bottom decrements the Scale value, and movement toward the left or top increments the Scale value.

<Key><osfUp>:
    For vertical Scales, moves the slider up one increment and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_TOP, movement toward the top increments the Scale value. If XmNprocessingDirection is XmMAX_ON_BOTTOM, movement toward the top decrements the Scale value.

<Key><osfDown>:
    For vertical Scales, moves the slider down one increment and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_BOTTOM, movement toward the bottom increments the Scale value. If XmNprocessingDirection is XmMAX_ON_TOP, movement toward the bottom decrements the Scale value.

<Key><osfLeft>:
    For horizontal Scales, moves the slider one increment to the left and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_LEFT, movement toward the left increments the Scale value. If XmNprocessingDirection is XmMAX_ON_RIGHT, movement toward the left decrements the Scale value.

<Key><osfRight>:
    For horizontal Scales, moves the slider one increment to the right and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_RIGHT, movement toward the right increments the Scale value. If XmNprocessingDirection is XmMAX_ON_LEFT, movement toward the right decrements the Scale value.

<Ctrl><Key><osfUp> or <Key><osfPageUp>:
    For vertical Scales, moves the slider up one multiple increment and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_TOP, movement toward the top increments the Scale value. If XmNprocessingDirection is XmMAX_ON_BOTTOM, movement toward the top decrements the Scale value.

<Ctrl><Key><osfDown> or <Key><osfPageDown>:
    For vertical Scales, moves the slider down one multiple increment and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_BOTTOM, movement toward the bottom increments the Scale value. If XmNprocessingDirection is XmMAX_ON_TOP, movement toward the bottom decrements the Scale value.

<Ctrl><Key><osfLeft> or <Key><osfPageLeft>:
    For horizontal Scales, moves the slider one multiple increment to the left and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_LEFT, movement toward the left increments the Scale value. If XmNprocessingDirection is XmMAX_ON_RIGHT, movement toward the left decrements the Scale value.

<Ctrl><Key><osfRight> or <Key><osfPageRight>:
    For horizontal Scales, moves the slider one multiple increment to the right and calls the XmNvalueChangedCallback callbacks. If XmNprocessingDirection is XmMAX_ON_RIGHT, movement toward the right increments the Scale value. If XmNprocessingDirection is XmMAX_ON_LEFT, movement toward the right decrements the Scale value.

<Key><osfBeginLine> or <Key><osfBeginData>:
    Moves the slider to the minimum value and calls the XmNvalueChangedCallback callbacks.

<Key><osfEndLine> or <Key><osfEndData>:
    Moves the slider to the maximum value and calls the XmNvalueChangedCallback callbacks.

<Key><osfNextField>:
    Traverses to the first item in the next tab group. If the current tab group is the last entry in the tab group list, it wraps to the beginning of the tab group list.

<Key><osfPrevField>:
    Traverses to the first item in the previous tab group. If the beginning of the tab group list is reached, it wraps to the end of the tab group list.

<Key><osfHelp>:
    Calls the callbacks for XmNhelpCallback if any exist. If there are no help callbacks for this widget, this action calls the help callbacks for the nearest ancestor that has them.

  Virtual Bindings

The bindings for virtual keys are vendor specific. For information about bindings for virtual buttons and keys, see VirtualBindings(3).

RELATED

Composite(3), Constraint(3), XCore(3), XmCreateScale(3), XmManager(3), XmScaleGetValue(3), XmScaleSetValue(3), XmVaCreateScale(3), and XmVaCreateManagedScale(3).