325 lines
15 KiB
HTML
325 lines
15 KiB
HTML
<HTML><HEAD><TITLE>Tk Built-In Commands - scale manual page</TITLE></HEAD>
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<BODY bgcolor = #c3c3ff>
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<H2><IMG ALIGN=BOTTOM SRC="./Img/ManPageBlue.gif"> scale</H2>
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<I>Create and manipulate scale widgets</I><P><IMG ALIGN=TOP SRC="./Img/line-red.gif">
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<H3><A NAME="M2">SYNOPSIS</A></H3>
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(<B>scale</B><I> widget-name </I>?<I>options</I>?)<BR>
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<H3><A NAME="M3">STANDARD OPTIONS</A></H3>
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<PRE>
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<B><A HREF="options.n.html#M:activebackground">:activebackground</A></B> <B><A HREF="options.n.html#M:background">:background</A></B>
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<B><A HREF="options.n.html#M:borderwidth">:borderwidth</A></B> <B><A HREF="options.n.html#M:cursor">:cursor</A></B>
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<B><A HREF="options.n.html#M:font">:font</A></B> <B><A HREF="options.n.html#M:foreground">:foreground</A></B>
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<B><A HREF="options.n.html#M:highlightbackground">:highlightbackground</A></B> <B><A HREF="options.n.html#M:highlightcolor">:highlightcolor</A></B>
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<B><A HREF="options.n.html#M:highlightthickness">:highlightthickness</A></B> <B><A HREF="options.n.html#M:orient">:orient</A></B>
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<B><A HREF="options.n.html#M:relief">:relief</A></B> <B><A HREF="options.n.html#M:repeatdelay">:repeatdelay</A></B>
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<B><A HREF="options.n.html#M:repeatinterval">:repeatinterval</A></B> <B><A HREF="options.n.html#M:takefocus">:takefocus</A></B>
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<B><A HREF="options.n.html#M:troughcolor">:troughcolor</A></B>
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</PRE>
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<H3><A NAME="M19">WIDGET-SPECIFIC OPTIONS</A></H3>
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<DL>
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<P>
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<DT><I>Name</I>: <B>bigIncrement</B>
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<DT><I>Class</I>: <B>BigIncrement</B>
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<DT><I>Option keyword</I>: <B><A NAME="M20">:bigincrement</A></B>
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<DT><I>STklos slot name</I>: <B>big-increment</B>
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<DD>Some interactions with the scale cause its value to change by
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``large'' increments; this option specifies the size of the
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large increments. If specified as 0, the large increments default
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to 1/10 the range of the scale.
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<P>
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<P>
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<DT><I>Name</I>: <B>command</B>
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<DT><I>Class</I>: <B>Command</B>
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<DT><I>Option keyword</I>: <B><A NAME="M21">:command</A></B>
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<DT><I>STklos slot name</I>: <B>command</B>
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<DD>Specifies a STk command to invoke whenever the scale's
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value is changed via a widget command.
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The procedure is called with a real number indicating the
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new value of the scale. Example:
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<P>
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</DL>
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<UL>
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<UL>
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(scale '.s :command (lambda (x)
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(format #t "New position is ~S\n" x)))
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</UL>
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</UL>
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<DL>
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<P>
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<DT><I>Name</I>: <B>digits</B>
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<DT><I>Class</I>: <B>Digits</B>
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<DT><I>Option keyword</I>: <B><A NAME="M22">:digits</A></B>
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<DT><I>STklos slot name</I>: <B>digits</B>
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<DD>An integer specifying how many significant digits should be retained
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when converting the value of the scale to a string.
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If the number is less than or equal to zero, then the scale picks
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the smallest value that guarantees that every possible slider
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position prints as a different string.
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<P>
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<P>
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<DT><I>Name</I>: <B>from</B>
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<DT><I>Class</I>: <B>From</B>
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<DT><I>Option keyword</I>: <B><A NAME="M23">:from</A></B>
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<DT><I>STklos slot name</I>: <B>from</B>
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<DD>A real value corresponding to the left or top end of the scale.
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<P>
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<P>
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<DT><I>Name</I>: <B><A HREF="./label.n.html">label</A></B>
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<DT><I>Class</I>: <B><A HREF="./label.n.html">Label</A></B>
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<DT><I>Option keyword</I>: <B><A NAME="M24">:label</A></B>
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<DT><I>STklos slot name</I>: <B><A HREF="./label.n.html">label</A></B>
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<DD>A string to display as a label for the scale. For
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vertical scales the label is displayed just to the right of the
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top end of the scale. For horizontal scales the label is displayed
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just above the left end of the scale. If the option is specified
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as an empty string, no label is displayed.
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<P>
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<P>
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<DT><I>Name</I>: <B>length</B>
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<DT><I>Class</I>: <B>Length</B>
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<DT><I>Option keyword</I>: <B><A NAME="M25">:length</A></B>
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<DT><I>STklos slot name</I>: <B>length</B>
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<DD>Specifies the desired long dimension of the scale in screen units
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(i.e. any of the forms acceptable to <B>Tk_GetPixels</B>).
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For vertical scales this is the scale's height; for horizontal scales
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it is the scale's width.
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<P>
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<P>
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<DT><I>Name</I>: <B>resolution</B>
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<DT><I>Class</I>: <B>Resolution</B>
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<DT><I>Option keyword</I>: <B><A NAME="M26">:resolution</A></B>
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<DT><I>STklos slot name</I>: <B>resolution</B>
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<DD>A real value specifying the resolution for the scale.
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If this value is greater than zero then the scale's value will always be
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rounded to an even multiple of this value, as will tick marks and
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the endpoints of the scale. If the value is less than zero then no
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rounding occurs. Defaults to 1 (i.e., the value will be integral).
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<P>
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<P>
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<DT><I>Name</I>: <B>showValue</B>
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<DT><I>Class</I>: <B>ShowValue</B>
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<DT><I>Option keyword</I>: <B><A NAME="M27">:showvalue</A></B>
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<DT><I>STklos slot name</I>: <B>show-value</B>
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<DD>Specifies a boolean value indicating whether or not the current
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value of the scale is to be displayed.
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<P>
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<P>
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<DT><I>Name</I>: <B>sliderLength</B>
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<DT><I>Class</I>: <B>SliderLength</B>
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<DT><I>Option keyword</I>: <B><A NAME="M28">:sliderlength</A></B>
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<DT><I>STklos slot name</I>: <B></B>
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<DD>Specifies the size of the slider, measured in screen units along the slider's
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long dimension. The value may be specified in any of the forms acceptable
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to <B>Tk_GetPixels</B>.
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<P>
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<P>
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<DT><I>Name</I>: <B>sliderRelief</B>
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<DT><I>Class</I>: <B>SliderRelief</B>
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<DT><I>Option keyword</I>: <B><A NAME="M29">:sliderrelief</A></B>
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<DT><I>STklos slot name</I>: <B>slider-relief</B>
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<DD>Specifies the relief to use when drawing the slider, such as <B>raised</B>
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or <B>sunken</B>.
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<P>
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<P>
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<DT><I>Name</I>: <B>state</B>
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<DT><I>Class</I>: <B>State</B>
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<DT><I>Option keyword</I>: <B><A NAME="M30">:state</A></B>
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<DT><I>STklos slot name</I>: <B>state</B>
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<DD>Specifies one of three states for the scale: <B>"normal"</B>,
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<B>"active"</B>, or <B>"disabled"</B>.
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If the scale is disabled then the value may not be changed and the scale
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won't activate.
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If the scale is active, the slider is displayed using the color
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specified by the <B>activeBackground</B> option.
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<P>
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<P>
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<DT><I>Name</I>: <B>tickInterval</B>
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<DT><I>Class</I>: <B>TickInterval</B>
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<DT><I>Option keyword</I>: <B><A NAME="M31">:tickinterval</A></B>
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<DT><I>STklos slot name</I>: <B>tick-interval</B>
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<DD>Must be a real value.
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Determines the spacing between numerical
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tick marks displayed below or to the left of the slider.
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If 0, no tick marks will be displayed.
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<P>
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<P>
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<DT><I>Name</I>: <B>to</B>
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<DT><I>Class</I>: <B>To</B>
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<DT><I>Option keyword</I>: <B><A NAME="M32">:to</A></B>
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<DT><I>STklos slot name</I>: <B>to</B>
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<DD>Specifies a real value corresponding
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to the right or bottom end of the scale.
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This value may be either less than or greater than the <B>from</B> option.
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<P>
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<P>
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<DT><I>Name</I>: <B>variable</B>
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<DT><I>Class</I>: <B>Variable</B>
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<DT><I>Option keyword</I>: <B><A NAME="M33">:variable</A></B>
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<DT><I>STklos slot name</I>: <B>variable</B>
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<DD>Specifies the name of a global variable to link to the scale. Whenever the
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value of the variable changes, the scale will update to reflect this
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value.
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Whenever the scale is manipulated interactively, the variable
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will be modified to reflect the scale's new value.
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<P>
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<P>
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<DT><I>Name</I>: <B>width</B>
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<DT><I>Class</I>: <B>Width</B>
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<DT><I>Option keyword</I>: <B><A NAME="M34">:width</A></B>
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<DT><I>STklos slot name</I>: <B>width</B>
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<DD>Specifies the desired narrow dimension of the trough in screen units
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(i.e. any of the forms acceptable to <B>Tk_GetPixels</B>).
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For vertical scales this is the trough's width; for horizontal scales
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this is the trough's height.
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<P>
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</DL>
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<H3><A NAME="M35">DESCRIPTION</A></H3>
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The <B>scale</B> procedure creates a new window (given by the
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<I>widget-name</I> argument) and makes it into a scale widget.
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Additional
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options, described above, may be specified on the procedure line
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or in the option database
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to configure aspects of the scale such as its colors, orientation,
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and relief. The <B>scale</B> procedure returns its
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<I>widget-name</I> argument. At the time this procedure is invoked,
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there must not exist a window named <I>widget-name</I>, but
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<I>widget-name</I>'s parent must exist.
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<P>
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A scale is a widget that displays a rectangular <I>trough</I> and a
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small <I>slider</I>. The trough corresponds to a range
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of real values (determined by the <B>from</B>, <B>to</B>, and
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<B>resolution</B> options),
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and the position of the slider selects a particular real value.
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The slider's position (and hence the scale's value) may be adjusted
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with the mouse or keyboard as described in the BINDINGS
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section below. Whenever the scale's value is changed, a STk
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procedure is invoked (using the <B>command</B> option) to notify
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other interested widgets of the change.
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In addition, the value
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of the scale can be linked to a STk variable (using the <B>variable</B>
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option), so that changes in either are reflected in the other.
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<P>
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Three annotations may be displayed in a scale widget: a label
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appearing at the top right of the widget (top left for horizontal
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scales), a number displayed just to the left of the slider
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(just above the slider for horizontal scales), and a collection
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of numerical tick marks just to the left of the current value
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(just below the trough for horizontal scales). Each of these three
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annotations may be enabled or disabled using the
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configuration options.
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<H3><A NAME="M36">WIDGET PROCEDURE</A></H3>
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The <B>scale</B> procedure creates a new STk procedure whose
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name is <I>widget-name</I>. This
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procedure may be used to invoke various
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operations on the widget. It has the following general form:
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<PRE>(<I>widget-name option </I>?<I>arg arg ...</I>?)</PRE>
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<I>Option</I> and the <I>arg</I>s
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determine the exact behavior of the procedure. The following
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procedures are possible for scale widgets:
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<P>
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<DL>
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<DT><A NAME="M37">(<I>widget-name '</I><B>cget</B> <I>option</I>)</A><DD>
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Returns the current value of the configuration option given
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by <I>option</I>.
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<I>Option</I> may have any of the values accepted by the <B>scale</B>
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procedure.
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<P>
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<DT><A NAME="M38">(<I>widget-name '</I><B>configure</B> ?<I>option</I>? ?<I>value option value ...</I>?)</A><DD>
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Query or modify the configuration options of the widget.
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If no <I>option</I> is specified, returns a list describing all of
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the available options for <I>widget-name</I> (see <B>Tk_ConfigureInfo</B> for
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information on the format of this list). If <I>option</I> is specified
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with no <I>value</I>, then the procedure returns a list describing the
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one named option (this list will be identical to the corresponding
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sublist of the value returned if no <I>option</I> is specified). If
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one or more <I>option-value</I> pairs are specified, then the procedure
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modifies the given widget option(s) to have the given value(s); in
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this case the procedure returns an empty list.
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<I>Option</I> may have any of the values accepted by the <B>scale</B>
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procedure.
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<P>
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<DT><A NAME="M39">(<I>widget-name '</I><B>coords </B>)</A><DD>
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<DT><A NAME="M40">(<I>widget-name '</I><B>coords </B><I>value</I>)</A><DD>
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Returns a list whose elements are the x and y coordinates of
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the point along the centerline of the trough that corresponds
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to <I>value</I>.
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If <I>value</I> is omitted then the scale's current value is used.
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<P>
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<DT><A NAME="M41">(<I>widget-name '</I><B>get</B>)</A><DD>
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<DT><A NAME="M42">(<I>widget-name '</I><B>get</B> <I>x y</I>)</A><DD>
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If <I>x</I> and <I>y</I> are omitted, returns the current value
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of the scale. If <I>x</I> and <I>y</I> are specified, they give
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pixel coordinates within the widget; the procedure returns
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the scale value corresponding to the given pixel.
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Only one of <I>x</I> or <I>y</I> is used: for horizontal scales
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<I>y</I> is ignored, and for vertical scales <I>x</I> is ignored.
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<P>
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<DT><A NAME="M43">(<I>widget-name '</I><B>identify</B> <I>x y</I>)</A><DD>
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Returns a string indicating what part of the scale lies under
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the coordinates given by <I>x</I> and <I>y</I>.
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A return value of <B>"slider"</B> means that the point is over
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the slider; <B>"trough1"</B> means that the point is over the
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portion of the slider above or to the left of the slider;
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and <B>"trough2"</B> means that the point is over the portion
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of the slider below or to the right of the slider.
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If the point isn't over one of these elements, an empty list
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is returned.
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<P>
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<DT><A NAME="M44">(<I>widget-name '</I><B>set</B> <I>value</I>)</A><DD>
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This procedure is invoked to change the current value of the scale,
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and hence the position at which the slider is displayed. <I>Value</I>
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gives the new value for the scale.
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The procedure has no effect if the scale is disabled.
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<P>
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</DL>
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<H3><A NAME="M45">BINDINGS</A></H3>
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Tk automatically creates class bindings for scales that give them
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the following default behavior.
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Where the behavior is different for vertical and horizontal scales,
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the horizontal behavior is described in parentheses.
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<OL>
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<LI>
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If button 1 is pressed in the trough, the scale's value will
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be incremented or decremented by the value of the <B>resolution</B>
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option so that the slider moves in the direction of the cursor.
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If the button is held down, the action auto-repeats.
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<LI>
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If button 1 is pressed over the slider, the slider can be dragged
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with the mouse.
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<LI>
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If button 1 is pressed in the trough with the Control key down,
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the slider moves all the way to the end of its range, in the
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direction towards the mouse cursor.
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<LI>
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If button 2 is pressed, the scale's value is set to the mouse
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position. If the mouse is dragged with button 2 down, the scale's
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value changes with the drag.
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<LI>
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The Up and Left keys move the slider up (left) by the value
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of the <B>resolution</B> option.
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<LI>
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The Down and Right keys move the slider down (right) by the value
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of the <B>resolution</B> option.
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<LI>
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Control-Up and Control-Left move the slider up (left) by the
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value of the <B>bigIncrement</B> option.
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<LI>
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Control-Down and Control-Right move the slider down (right) by the
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value of the <B>bigIncrement</B> option.
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<LI>
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Home moves the slider to the top (left) end of its range.
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<LI>
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End moves the slider to the bottom (right) end of its range.
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</OL>
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<P>
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If the scale is disabled using the <B>state</B> option then
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none of the above bindings have any effect.
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<P>
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The behavior of scales can be changed by defining new bindings for
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individual widgets or by redefining the class bindings.
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<P><IMG ALIGN=TOP SRC="./Img/line-red.gif">
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<A HREF=./STk-hlp.html><IMG ALIGN=BOTTOM SRC="./Img/RefBookBlue.gif"> Back to the <B>STk</B> main page</A>
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</BODY></HTML>
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