Applet User's Guide



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The Basics

Applet Layout

In general the applet is organized as follows:

At the top of the applet is an area with buttons on the left hand side. Pressing one of these buttons gets you a control panel on the right hand side, from which commands are available.
Below this control area is the graph window. Click in this area to add or select points.

Adding Points

Just click in the white graph area of the applet to add points.
If you find no points are being added, go to the Points control panel, by clicking the 'points' button in the control area. Make sure the 'Add Points' checkbox is checked. Click it again to make sure. You should now be able to add points.
To quickly add a number of points, click on the 'Add Random' button to add some random points. The number of random points to add can be entered in the field to the right.

Selecting Points

Go to the Points control panel, by clicking the 'points' button in the control area. Click the checkbox labled 'Select Points'. When you move the mouse back into the applet window, you should notice that the point closest to the mouse is highlighted.
If you press the mouse button now, the highlighted point will be selected, which is indicated by a change in the point's colour. If you press the mouse button again, the point will be deselected. To select and deselect multiple points, hold down the shift key when clicking near the points.

Removing Points

To remove all the points in the graph window, go to the Points control panel, and click the button labled 'Delete All'.
To remove only some of the points in the graph, select them as described in the section above, and then click the 'Delete' button in the Points control panel. The selected points will be deleted.

The Graphs

To get the applet to plot graphs, click in the 'graphs' button to show the Graphs control panel. There are a number of checkable options available from this panel.

Advanced Features

Running Demos

The applet is capable of running demo files. To run a demo file, go to the Commands control panel. Type the demo file's name in the field next to the 'Play Demo File' button, then click the button. The demo files are listed on the web-page with the applet.

Changing View

To change the view of the drawing pane of the applet, <ALT>-click on the drawing pane to zoom in, and <SHIFT><ALT>-click to zoom out. (NB: Use the left mouse button).

To change view, you can also use a command. To issue a command, go to the Commands control panel, and click in the one-line textfield at the bottom left of the control panel. This textfield is the command line.

To change the zoom level, type zoom x on the command line, replacing x by a number. The smaller the number, the smaller everything will get, or the more you 'zoom out'. The default zoom value is 100. Examples:
zoom 200 #makes everything spaced out twice as distantly
zoom 50 #makes everything twice as close together
zoom #restores default zoom value of 100

Changing the origin is possible via the translate command. Type translate x,y into the command line to change the origin of the view to be the point x,y. Note that this does not affect the coordinates of the points you add, merely the location you're looking at in the graph. The default origin is 0,0.

Command Parser

The applet has a built-in command line, on which you can issue text commands to the applet. To change the view-mode, for example, use the zoom and translate commands. In general, any button or checkbox you click in the interface corresponds to a command you can issue.
To learn what commands do what, try clicking the buttons and then examining the command display, above the command line in the Commands control panel. A probably complete list, with brief descriptions of each command, is given below.

The following states can be set and checked using the set <str> <bool> and check <str> commands:

All the above commands can also be typed into a text file, that can then be played as a demo file. Similarly, recorded demo files can be edited in any text editor. In demo files the comment character is '# '.

The Application

This applet is also available as a Java application, for you to run on your home computer. Download it from here. The application allows you to save demo-files, as well as play them back. To save demo-files go to the Commands control panel, type the file name into the textfield next to the 'Log to File' checkbox, then click the checkbox. All commands you issue, by typing into the command line or using the interface, will be written into the file. To stop recording, un-check the 'Log to File' checkbox.

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by Jacob Eliosoff & Richard Unger, October 1998