3.2 Java1492-plotting large quantities of data using java  (Page 8/27)

Two overloaded constructors

There are two overloaded versions of the constructor for the PlotALot01 class. One overloaded version accepts several incoming parameters allowing the user to control various aspects of the plotting format. (An example of the use of this constructor is shown in Figure 5 .) A second overloaded version accepts a title string only and sets all of theplotting parameters to default values. (An example of the use of this constructor is shown in Figure 1 .)

(You can easily modify the default values and recompile the class if you prefer different default values.)

Constructor parameters

The parameters for the version of the constructor that accepts plotting parameters are:

• String title: Title for the Frame object. This title is concatenated with the page number and the result appears in the banner at the top of thePage as shown in Figure 1 .
• int frameWidth: The Frame width in pixels.
• int frameHeight: The Frame height in pixels.
• int traceSpacing: Distance between trace axes in pixels.
• int sampSpace: Number of pixels dedicated to each data sample in pixels per sample. (Must be 1 or greater.)
• int ovalWidth: Width of an oval that is used to mark the sample value on the plot. (See Figure 5 for a good example of the ovals. Set the oval width and height parameters to zero to eliminate the ovals altogether.)
• int ovalHeight: Height of an oval that is used to mark the sample value on the plot.

Two plotting objects for test purposes

For self-test purposes, the main method instantiates and feeds two independent plotting objects. Plotting parameters are specified for thefirst plotting object and the stack of pages for this plotting object is located 401 pixels to the right of the upper left corner of the screen. The outputproduced by this plotting object is shown in Figure 5 below. (The two pages in the screen shot in Figure 5 were manually relocated and positioned for reasons that I will explain later.)

Figure 5. Self-test output for PlotALot01.

Default plotting parameters are used for the second plotting object and the stack of pages is located in the default location at the upper left corner ofthe screen. The output produced by this plotting object was shown earlier in Figure 1 .

The data to be plotted

Most of the data that is fed to each plotting object is white random noise produced by a random noise generator. However, fifteen of the data values fed tothe first plotting object are not random.

Transition from trace to trace on the same page

Eight of the data values for the first plotting object are set to 0,0,20,20,-20,-20,0,0. The result can be seen at the end of the first trace andthe beginning of the second trace in Page 0 in Figure 5 . Note that the last four plotted points for the first trace have values of 0,0,20, and 20. Then note thatthe first four plotted points on the second trace have values of -20, -20, 0, and 0. This confirms the proper transition from one trace to the next on thesame page with no loss of data values in the transition.

Transition from page to page

Seven of the values for the first plotting object are set to values of 0,0,25,-25,25,0,0. The result can be seen at the end of the last trace on Page 0and the beginning of the first trace on Page 1 in Figure 5 . Note that the last three plotted points in the last trace on Page 0 have values of 0, 0, and 25.Then note that the first four plotted points in the first trace on Page 1 have values of -25, 25, 0, and 0. This confirms the proper transition from one pageto the next with no loss of data in the transition.