Graphic display

Graphic display

The graphic display provides a two dimensional high speed plot control window with zooming and autorange capability. The object can plot one or two dimensional numerical data or directly evaluate given functions. An arbitrary number of curves can be displayed simultaneously.
Fig. 1: Graphic display control

Common properties

Most properies in the property dialog affect all curves: The "Min x", "Min y", "Max x", and "Max y" properties specify an initial scaling range. Using properties "Autorange x" and "Autorange y" automatic scaling can be switched on for the particular axis. With "X-title" and "Y-title" properties axis labels can be specified. The font used for labelling can be choosen during edit time pressing the button in the font property. In the "Curve count" properties specify the number of simultaneously displayed curves. To specify properties of the individual curves, press the button in the "Curves" property.

Curve properties

Fig. 2: Curve properties In the curve property dialog use the "choose curve" controls to switch to the curve you want to change properties. Each curve has the following options:

• Graph title:This sets the label which appears in the legend below the plot.
• Color:The color that is used for painting lines or points.
• Curve type:When set to "Line" all data points are connected, otherwise they are drawn as single points.
• Multidim. input:Only available when data source is a vector. When switched on the source vector must be created with a vector memory. This is useful for drawing several curves at once.
• Wrap around detection:If set to yes, the object tries do detect when the scale vector restarts from the beginning and in this case prevents connecting data points. This is useful when one data vector contains multiple curves stacked behind each other and only when "curve type" is set to "Line".
• Data source:When set to "Vector", two input variables are created for scale and data vector. Data to be plotted is taken out of these input variables. If the scale input vector has no data, the data vector is plotted over the element index. If this property is set to "Function", the code window is enable. One must provide a function "double gety(double x)" which is called for every plotted data point x. The function must give out the appropriate y value. An additional function precalc is provided which is called before "gety" is called the first time. This can be used for doing calculations which effect all data points, for example calculating a mean value etc.. Both functions are compiled to a single shared object file which is included during execution (see Calculator object). For passing data between both functions normal global C variables can be used.

Plot functions during run time

Using the left mouse button parts of the plot can be zoomed. When a zoom is performed autorange is switched off. Unzoom is done by pressing the right mouse button somewhere in the plot.