Xraw: StripChart widget

StripChart widget

Application Header file	<Xraw/StripChart.h>
Class Header file	<Xraw/StripChartP.h>
Class	stripChartWidgetClass
Class Name	StripChart
Superclass	Simple --> Core

The StripChart widget is used to provide a real time graphical chart of a single value. This widget is used by xload to provide the load graph. It will read data from an application, and update the chart at the update interval specified.

New Resources

Name	Class	Type	Notes	Default Value
foreground	Foreground	Pixel		XtDefaultForeground
getValue	Callback	XtCallbackList		NULL
highlight	Foreground	Pixel		XtDefaultForeground
jumpScroll	JumpScroll	int	A	half the width of the widget
minScale	Scale	int		1
update	Interval	int		10

foreground A pixel value which indexes the widget's colormap to derive the color that will be used to draw the graph.

getValue This is a list of functions to call every update seconds. This function will get the value to be graphed by the StripChart widget. The section Getting the StripChart Value will describe the calling interface in more detail. This callback list should contain only one function. If this callback list contains more than one function, the behavior is undefined.

highlight A pixel value which indexes the widget's colormap to derive the color that will be used to draw the scale lines on the graph.

jumpScroll When the graph reaches the right edge of the window it must be scrolled to the left. This resource specifies the number of pixels it will jump. Smooth scrolling can be achieved by setting this resource to 1.

minScale The minimum scale for the graph. The number of divisions on the graph will always be greater than or equal to this value.

update The number of seconds between graph updates. Each update is represented on the graph as a 1 pixel wide line. Every update seconds the getValue procedure will be used to get a new graph point, and this point will be added to the right end of the StripChart.

foreground	A pixel value which indexes the widget's colormap to derive the color that will be used to draw the graph.
getValue	This is a list of functions to call every update seconds. This function will get the value to be graphed by the StripChart widget. The section Getting the StripChart Value will describe the calling interface in more detail. This callback list should contain only one function. If this callback list contains more than one function, the behavior is undefined.
highlight	A pixel value which indexes the widget's colormap to derive the color that will be used to draw the scale lines on the graph.
jumpScroll	When the graph reaches the right edge of the window it must be scrolled to the left. This resource specifies the number of pixels it will jump. Smooth scrolling can be achieved by setting this resource to 1.
minScale	The minimum scale for the graph. The number of divisions on the graph will always be greater than or equal to this value.
update	The number of seconds between graph updates. Each update is represented on the graph as a 1 pixel wide line. Every update seconds the getValue procedure will be used to get a new graph point, and this point will be added to the right end of the StripChart.

Getting The StripChart Value

The StripChart widget will call the application routine passed to it as the getValue callback function every update seconds to obtain another point for the StripChart graph.

The calling interface for the getValue callback is:

void (*getValueProc)(w, client_data, value)
	Widget w;
	XtPointer client_data;
	XtPointer value; /* double * */

w	Specifies the StripChart widget.
client_data	Specifies the client data.
value	Returns a pointer to a double. The application should set the address pointed to by this argument to a double containing the value to be graphed on the StripChart.

This function is used by the StripChart to call an application routine. The routine will pass the value to be graphed back to the the StripChart in the value field of this routine.

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Vladimir T. Romanovski
romsky@hp1.oea.ihep.su