BTerm Keyboard Mapping: Customize Your Actions

Estimated reading time: 14 minutes

5250 Terminal Keyboard Mapping

Default Keyboard Settings

The following keyboard ‘actions’ are identified and mapped to either an IBM Aid key that gets submitted or a terminal command to edit field content or to move the cursor position.

Telnet Flags

A few of the ‘Actions’ that submit but do not send Aid Key to the IBM i need to effect the Telnet message header instead. According to http://www.ietf.org/rfc/rfc1205.txt, there is a 16 bit flag field in the Telnet header. Eight of those bits are reserved and should be set to zero.

Customizing the Keyboard

To map Actions not set by default or to customize keyboard mapping, you can add a few lines of JavaScript code to the ~\Pages\Terminal\Terminal.cshtml RazorPage.

The JavaScript code that implements the ASNA 5250 Terminal emulator subscribes to the following browser events:

document.body.onkeydown
document.body.onkeypress

When keyboard input is identified, the input is normalized into a Key object with the following properties:

Key = (code, ctrlKey, altKey, shiftKey) => {
      this.code     = code;
      this.ctrlKey  = ctrlKey;
      this.altKey   = altKey;
      this.shiftKey = shiftKey;
   }

This Key object needs to be mapped into either an Action, as noted above, or a character to be added to the field at the cursor’s position. Before applying the Defaults above, the ASNA 5250 Terminal emulator JavaScript code checks for the global function WingsTerminalMapKey. If it exists as a function, then it is called with the following parameters:

Input event object instance

This is the object we need to change to indicate the mapping. the two properties are:

InputEvent = function ( action, character) {
   this.action = action;
   this.character = character;
}

Where action should be assigned a string value and character should be assigned a string value with one character to be added at the cursor’s position (if positioned at an input field).

Only one of the properties should be changed unless that key event should be processed by the default action or character.

Keyboard Mapping example

For example, the following implementation of global function WingsTerminalMapKey will map the ‘RESET’ action to the Ctrl + R key combination. Note: the default ‘Esc’ mapping would still work. To disable the default code, map it to a blank action.

Adding Hot-keys for International Characters

When an international character is not available on the keyboard, it is still possible to produce the symbol adding some customization.

Even the numeric keypad (when Num Lock is ON), may be used to enter characters – giving its ascii code. For example, Alt 164 on US keyboard produces the ‘ñ’ symbol - it may be simpler to remember to produce these, by a combination with the Ctrl key. You can easily map ‘ñ’ or accent on vowels with a sequence such as Ctrl, like in the following example:

<script type="text/javascript">
   WingsTerminalMapKey = (inputKey, wasKeyPress, outEvent) => {
      if ( inputKey.ctrlKey ) {
         switch( String.fromCharCode(inputKey.code).toUpperCase() ) {
            case 'N' :
               outEvent.character = 'ñ';
            break;
            case 'A' :
               outEvent.character = 'á';
            break;
            case 'E' :
               outEvent.character = 'é';
            break;
            case 'I' :
               outEvent.character = 'í';
            break;
            case 'O' :
               outEvent.character = 'ó';
            break;
            case 'U' :
              outEvent.character = 'ú';
            break;
         }
      }
   }
</script>