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Outline

Nebula Visualization is a widgets library for data visualization in science, engineering and SCADA areas. XY diagrams draw two groups of numbers as a set of XY coordinates. XY diagrams show the relationship of two records.

Platforms:	32/64bit 32/64bit 32/64bit
Requirements:	None
Known limitations:	None
Status:	Stable
Extensibility:	JavaScript
Supported signal types:	Numerical signal (Float, Integer,..) Integer array Float array Struct Manual fill
Chart Parameters:	Title: No Title, Description, Plot Name, Plot Description. Options: Annotated, Show Legend, Show Title, Show Grid. Max Points: Limits the maximum number of points to be displayed. Nebula Script: Extend the chart with Java Script. Apply Script: Enables/Disables the Nebula scripting. Manual Fill: Disables the provider's default signal processing; instead, the script shall provide the display data.
Plot Parameters:	Members : Identify the structure or array elements you want to display. Use a comma-separated list of all members, e.g.'X,Y'. Samples : Identify the samples you want to display. Use a comma-separated list of all sample indices, for example, '0,1,5-8'.

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Compatible signal data

The XY chart provider supports struct signals, numerical arrays or simple numerical signals. Arrays signals with 2 members are usually the best choice for XY charts.

	time;x;y
	0.000000ms;0.3332716083675362;9.994444958828685
	0.000010ms;0.3665845116956737;9.993278530881888
	0.000020ms;0.3998933418663416;9.99200106660978
	0.000030ms;0.43319772878176954;9.990612580206397
	0.000040ms;0.46649730239355675;9.989113087099351
	0.000050ms;0.4997916927067833;9.987502603949663
	0.000060ms;0.5330805297841217;9.98578114865157
	0.000070ms;0.5663634437499467;9.98394874033234
	0.000080ms;0.599640064794446;9.982005399352042
	0.000090ms;0.6329100231777278;9.979951147303336
	0.000100ms;0.6661729492339299;9.977786007011224
	0.000110ms;0.6994284733753277;9.975510002532795

	

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Chart Configuration

You can modify the chart behavior under Preferences->impulse->Charts.

• You may add own charts or chart variants
• Modify existing charts (Chart Parameters)

• Title: No Title, Description, Plot Name, Plot Description.
• Options: Annotated, Show Legend, Show Title, Show Grid.
• Max Points: Limits the maximum number of points to be displayed.
• Nebula Script: Extend the chart with Java Script.
• Apply Script: Enables/Disables the Nebula scripting.
• Manual Fill: Disables the provider's default signal processing; instead, the script shall provide the display data.

You can extend the XY chart using scripts. To achieve this you have access to the nebula graph object.

  
	// graph: XYGraph figure ( https://eclipse.org/nebula/widgets/visualization/visualization.php)
	// x,y,width,height: geometry
	// color, background: Colors
	// readable: input of IReadableSamples
	
	// simple modifications
	graph.primaryXAxis.setAutoScale(false);
	graph.primaryXAxis.setTitle("my x");
	graph.primaryYAxis.setAutoScale(false);
	graph.primaryYAxis.setTitle("my y");
	graph.primaryYAxis.setDashGridLine(true);
	graph.primaryYAxis.setShowMajorGrid(true);

If you check both "Apply script" and "Manual Fill", the script shall load the sample data into the chart (the standard data handling is disabled):

  
	// add a trace - use "Manual Fill" flag to disable default traces
	importPackage(Packages.org.eclipse.nebula.visualization.xygraph.dataprovider);
	importPackage(Packages.org.eclipse.nebula.visualization.xygraph.figures);
	var traceDataProvider = new CircularBufferDataProvider(false);
	var length = Math.min(500, readable.getCount());
	traceDataProvider.setBufferSize(length);
	for (var n = 0; n < length; n++) {
		var value = readable.compoundAt(n);
	    if (!value.isNone()) {
	    	traceDataProvider.addSample(new Sample(value.getUnits(), value.floatValue()));
	    }
	}
	var trace = new Trace("my trace", graph.primaryXAxis, graph.primaryYAxis, traceDataProvider);
	trace.setForegroundColor(color);
	graph.addTrace(trace);

Beside the chart parameters, you can set the default plot parameters. You can override them in the actual plot.

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Plot Configuration

To display a chart in a given plot:

• Configure production/source to gain a compatible signal
• Set the plot type to "Chart",
• Configure the charts plot parameter ("Chart Style").

You can override the following plot parameters:

• Members : Identify the structure or array elements you want to display. Use a comma-separated list of all members, e.g.'X,Y'.
• Samples : Identify the samples you want to display. Use a comma-separated list of all sample indices, for example, '0,1,5-8'.

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Signal script to define chart data

Use the following signal script example to prepare chart data using a FloatArray signal. You may use a Signal Script Production or a recJs file.

 
	out.addMember( "x", null, ISample.FORMAT_DEFAULT);
	out.addMember( "y", null, ISample.FORMAT_DEFAULT);  
	var array = java.lang.reflect.Array.newInstance(java.lang.Double.TYPE, 2);
	for (t=0; t < 100000; t += 10) {
	    array[0] =  Math.sin((t + 100) / 3000.0) * 10.0;
	    array[1] =  Math.cos((t + 100) / 3000.0) * 10.0;       
		out.writeDoubleArray(t, false, array);
	}