CAPDM Tutorial Applets

Linear Functions

Functionality:

This simple applet allows you to control the variables of the equation of the line: y=mx + c. Both m and c can be modified and the graph shows the result.

Remote Control using JavaScript

Both C and M can be remotely changed through JavaScript. Both M and C can be changed in one step too. See the 'Runtime Applet API Calls' section below for details.

Examples

Change m to 2

Set c to 5

Set m to -1.3 and c to 5.7

Show 'About' dialog

How to Invoke the Applet

The applet can be invoked by embedding an APPLET tag into your HTML document (if you look at the source of this document you will see a working example you can copy). The table below details the basic parameters used and additional startup parameters that are specific to this applet.

<APPLET
   CODEBASE="../../../../classes"
   CODE="applet.capdm.qm.linearfunctions.LinearFunctionsApp" 
   NAME="LinearFunctions"   
   ALT="Linear Functions"
   WIDTH="360"
   HEIGHT="425">
</APPLET>

Basic Parameters	Use
CODEBASE="../../../../classes"	The CODEBASE of the applet must point at the top-level classes directory in order for the applet to be found.
CODE="applet.capdm.qm. linearfunctions.LinearFunctionsApp"	This required attribute gives the name of the file that contains the applet's compiled Applet subclass. This file is relative to the base URI of the applet.
ALT="Linear Functions"	This optional attribute specifies any text that should be displayed if the browser understands the APPLET tag but can't run Java applets.
NAME="LinearFunctions"	This optional attribute specifies a name for the applet instance, which makes it possible for applets on the same page to find (and communicate with) each other. If you intend to use JavaScript/Applet scripting then the applet must be named a shown.
WIDTH="360" HEIGHT="425"	These required attributes give the initial width and height (in pixels) of the applet display area, not counting any windows or dialogs that the applet brings up.
Applet Startup Parameters	Use
There are no startup parameters available for this applet

For more information on the use of the APPLET tag and other attributes you can use but which are not listed above, visit the W3.org specification page at: APPLET tag in HTML 4.

Runtime Applet API Calls

This applet can be called into using Javascript 1.1 while running. Although JavaScript can call the Applet directly, some convenient JavaScript functions have been created which deal with the details of the communication. The following table lists the call Names which can be made, and gives examples of their use and results.

API Call Name	Parameters	Use and Result
SetC	the new c value	`javascript:setC(5);` Changes the c value
SetM	the new m value	`javascript:setM(5);` Changes the m value
SetMandC	m and c values	`javascript:setMandC(1,4);` Changes the m value to 1 and the c value to 4
showAbout	none	`javascript:showAbout();` Shows the version dialog box of this applet.