Strip element STRIPELEMENT options

This page documents the configuration and behavior of strip elements.

STRIPELEMENT denotes an element whose concrete type is StripElement. Strip elements are the default element type of a stripchart widget:

stripchart .s
.s element create signal

The common element operations such as create, configure, activate, closest, bind, and delete are documented in ELEMENT.

Strip elements use the same underlying line-rendering machinery as line elements. Their data handling, axis mapping, pens, smoothing, symbols, error bars, value labels, weights, and styles therefore have the same semantics as described in LINEELEMENT.

Differences from line elements

A strip element exposes a restricted line-element option set intended for stripchart use.

In particular, the following LINEELEMENT options are not available for strip elements:

Option	Line-element feature
-areabackground	area-fill stipple background
-areaforeground	area-fill foreground
-areapattern	area filling with a solid or stipple pattern
-areaclose	area fill closure
-areaopacity	Cairo/SVG solid area fill opacity
-areatile	tiled area filling
-param	per-point parameter mapping returned by ELEMENT closest
-reduce	screen-space trace reduction
-state	line-element state option
-trace	filtering of increasing/decreasing X trace directions

All other options listed below use the same interpretation as the corresponding option on LINEELEMENT.

Data

Strip-element coordinates may be supplied with:

-x
-y
-xdata
-ydata
-data

For example:

.s element create signal -x {0 1 2 3 4} -y {1 4 2 5 3}

Rbc vector names may be used instead of literal coordinate lists:

vector create time voltage

time set    {0 1 2 3 4}
voltage set {1 4 2 5 3}

.s element create signal -x time -y voltage

The same transactional and left-to-right data-option semantics described for LINEELEMENT apply.

Non-finite data values and values outside the domain of a logarithmic axis form discontinuities in the rendered trace. Points on opposite sides of such a discontinuity are not connected.

Display decimation

Strip elements support -decimate none|auto with the same screen-density decimation semantics described for LINEELEMENT.

With -decimate auto, dense eligible strip data can be reduced before full world-to-screen mapping. The persistent data-domain cache supports monotonic X data, ranged Y updates, and pure tail growth of attached Rbc vectors.

This makes -decimate auto particularly suitable for continuously growing stripchart waveforms:

stripchart .s
vector create time voltage
.s element create signal -xdata time -ydata voltage -symbol none -showvalues no -smooth linear -decimate auto
time append $newTime
voltage append $newVoltage

If appended X values preserve the existing monotonic direction, only the newly exposed source data and affected cache summaries need to be examined. Shrinkage, non-monotonic growth, invalid data, or unknown source changes automatically fall back to the more general mapping path.

Decimation affects screen rendering only. PostScript output retains full source resolution.

Smoothing

Strip elements support the same smoothing modes as line elements:

linear
step
natural
cubic
quadratic
catrom

linear is the default.

Spline smoothing operates in mapped screen coordinates. Natural, quadratic, and Catmull-Rom smoothing require at least three mapped points.

As with line elements, spline smoothing never bridges a discontinuity. Each continuous run containing at least three mapped points is smoothed independently. Runs containing fewer than three mapped points remain ordinary linear trace segments.

Pens and symbols

Strip elements use line pens.

The built-in normal pen can be configured directly with options such as:

-color
-linewidth
-dashes
-offdash
-fill
-outline
-outlinewidth
-pixels
-symbol

A separately created line pen may be selected with -pen:

.s pen create tracePen -type line -color blue -linewidth 2
.s element configure signal -pen tracePen

-activepen selects the pen used when the element or individual data points are active.

See LINEELEMENT for detailed descriptions of line pens, symbols, symbol scaling, and symbol-density control.

Error bars of strip elements

Strip elements support the same symmetric and asymmetric error-bar data as line elements:

-xerror
-xlow
-xhigh
-yerror
-ylow
-yhigh

Their appearance is controlled by:

-showerrorbars
-errorbarcolor
-errorbarwidth
-errorbarcap

See LINEELEMENT for the complete error-bar semantics.

Value labels of strip elements

-valuecommand can replace the label text with a Tcl callback. See the custom value-label text section in LINEELEMENT for the callback arguments and error handling.

Strip elements can display coordinate values next to their data points using -showvalues.

Label appearance is controlled by:

-valueanchor
-valuecolor
-valuefont
-valuecommand
-valueoffset
-valueformat
-valuerotate
-valueshadow

See LINEELEMENT for value-selection and formatting behavior.

Weights and styles

-weights supplies a numeric weight for each data point and -styles maps weight ranges to named line pens.

The syntax and precedence rules are identical to those described for LINEELEMENT.

Strip element options

The complete strip-element option set is:

Option	Database name	Database class	Description
-activepen penName	activePen	ActivePen	Specifies the named line pen used when the element is active. An empty value disables the named active pen. The default is activeLine.
-bindtags tags	bindTags	BindTags	Specifies additional graph binding tags for the element. The default is all.
-color color	color	Color	Sets the built-in normal pen’s trace color. The default is navy blue.
-dashes dashes	dashes	Dashes	Sets the built-in normal pen’s trace dash pattern. An empty value selects a solid line. Each numeric list item accepts a Tcl integer expression.
-data data	data	Data	Supplies an even-length list of alternating X and Y values. Each literal list item accepts a Tcl numeric expression.
-decimate mode	decimate	Decimate	Selects automatic screen-density trace decimation. Accepted values are none and auto. The default is none. auto is applied only when the strip element and current display density are suitable.
-errorbarcap width	errorBarCap	ErrorBarCap	Sets the requested error-bar cap width. A positive value selects an explicit size; 0 automatically derives the size from the symbol size. The default is 1.
-errorbarcolor color	errorBarColor	ErrorBarColor	Sets the error-bar color. defcolor uses the trace color.
-errorbarwidth width	errorBarWidth	ErrorBarWidth	Sets the error-bar line width. The default is 1.
-fill color	fill	Fill	Sets the symbol fill color. defcolor uses the trace color; an empty value leaves symbols unfilled.
-hide boolean	hide	Hide	Controls whether the element is displayed. The default is no.
-hideplot boolean	hidePlot	HidePlot	Suppresses plotting of the element while keeping it in the display list and legend. A plot-hidden element does not contribute to automatic axis limits and is ignored by closest searches and element hit testing. The default is no.
-label text	label	Label	Sets the element label used by the legend. The initial label is the element name.
-labelrelief relief	labelRelief	LabelRelief	Sets the relief used for the element’s legend label. The default is flat.
-linewidth width	lineWidth	LineWidth	Sets the built-in normal pen’s trace width. The default is 1; 0 suppresses the trace.
-mapx axisName	mapX	MapX	Specifies the X axis used to map the element’s X coordinates. The axis must exist and must be an X axis. The default is x.
-mapy axisName	mapY	MapY	Specifies the Y axis used to map the element’s Y coordinates. The axis must exist and must be a Y axis. The default is y.
-maxsymbols number	maxSymbols	MaxSymbols	Requests a reduced symbol display density when the element contains many points. 0 draws symbols without this reduction. The default is 0.
-offdash color	offDash	OffDash	Sets the color used for the gaps of a dashed trace. An empty value leaves the gaps transparent; defcolor uses the trace color.
-outline color	outline	Outline	Sets the symbol outline color. defcolor uses the trace color.
-outlinewidth width	outlineWidth	OutlineWidth	Sets the non-negative width of symbol outlines. The default is 1.
-pen penName	pen	Pen	Specifies a named line pen containing the element’s normal drawing attributes. An empty value uses the element’s built-in pen.
-pixels size	pixels	Pixels	Sets the requested symbol size. The default is 0.125i.
-scalesymbols boolean	scaleSymbols	ScaleSymbols	Controls whether symbol sizes are automatically scaled as the axis ranges change. The default is yes.
-showerrorbars value	showErrorBars	ShowErrorBars	Selects which error bars are displayed: X, Y, both, or neither. The default is both.
-showvalues value	showValues	ShowValues	Selects which coordinate values are displayed next to data points. The default is no.
-smooth mode	smooth	Smooth	Selects line smoothing. Accepted modes are linear, step, natural, cubic, quadratic, and catrom. The default is linear.
-styles styles	styles	Styles	Specifies pens selected according to -weights. Each style is either penName or {penName min max}. Bare pen names receive successive implicit weight ranges. An empty value disables weight-selected styles.
-symbol symbol	symbol	Symbol	Sets the symbol drawn at data points. The default is circle.
-valueanchor anchor	valueAnchor	ValueAnchor	Sets the anchor used to position value labels relative to their data points. The default is s.
-valuecolor color	valueColor	ValueColor	Sets the color used to draw value labels.
-valuefont font	valueFont	ValueFont	Sets the font used to draw value labels.
-valuecommand cmd	valueCommand	ValueCommand	Formats value labels with a Tcl command prefix. The default is empty.
-valueoffset {dx dy}	valueOffset	ValueOffset	Moves the label anchor by signed integer pixels. Default: {0 0}.
-valueformat format	valueFormat	ValueFormat	Sets the printf-style format used for value labels. The default is %g.
-valuerotate degrees	valueRotate	ValueRotate	Sets the rotation angle of value labels in degrees. The default is 0.0.
-valueshadow shadow	valueShadow	ValueShadow	Specifies a shadow for value labels. An empty value disables the shadow.
-weights weights	weights	Weights	Supplies per-point numeric weights used to select pens through -styles. Each literal list item accepts a Tcl numeric expression.
-x data	xData	XData	Supplies the element’s X coordinates as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-xdata data	—	—	Synonym for -x.
-xerror data	xError	XError	Supplies symmetric X error magnitudes as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-xhigh data	xHigh	XHigh	Supplies the upper X error endpoints as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-xlow data	xLow	XLow	Supplies the lower X error endpoints as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-y data	yData	YData	Supplies the element’s Y coordinates as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-ydata data	—	—	Synonym for -y.
-yerror data	yError	YError	Supplies symmetric Y error magnitudes as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-yhigh data	yHigh	YHigh	Supplies the upper Y error endpoints as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.
-ylow data	yLow	YLow	Supplies the lower Y error endpoints as a list or Rbc vector. Each literal list item accepts a Tcl numeric expression.

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Copyright (c) George Yashin