swisscalc.display.numericDisplay.js

//
// Eric Morgan
// Copyright (c) 2014. 
//

// Class for displaying a floating-point number.

var swisscalc = swisscalc || {};
swisscalc.display = swisscalc.display || {};

// Constructor.
// groupDigits: Should digits be grouped by a comma (true/false) (default: true)
// maxLength: Maximum number of characters to display (default: 20)
swisscalc.display.numericDisplay = function(groupDigits, maxLength) { 
	this._display = "0";
	this._groupDigits = (typeof groupDigits === "undefined") ? true : groupDigits;
	this._maxLength = (typeof maxLength === "undefined") ? 20 : maxLength;
};

// Returns current display
swisscalc.display.numericDisplay.prototype.getCurrentDisplay = function() { 
	return (this._groupDigits)
		? swisscalc.lib.format.groupDigits(this._display)
		: this._display;
};

// Adds the given character to the display, if appropriate.
// The only valid digits are: 0...9, . (decimal). Must be a string.
swisscalc.display.numericDisplay.prototype.addDigit = function(digit) {
	// Don't go past maximum length...
	if (this._display.length >= this._maxLength)
		return;
		
	// Don't add multiple decimals...
	if (digit == "." && this._display.indexOf(".") >= 0)
		return;
		
	// If not a decimal and display is empty, remove 0...
	if (digit != "." && this._display == "0")
		this._display = "";
		
	// Add the digit to the end (note: '.' will result in '0.')...
	this._display += digit;
};

// Adds or removes the negative sign
swisscalc.display.numericDisplay.prototype.negate = function() {
	var fChar = this._display.charAt(0);
	this._display = (fChar == "-") ? this._display.substring(1) : "-" + this._display;
};

// Removes the last character if possible
swisscalc.display.numericDisplay.prototype.backspace = function() {
	var len = this._display.length;	
	if (len == 1)
		this._display = "0";
	else if (len == 2 && this._display.charAt(0) == "-")
		this._display = "0";
	else
		this._display = this._display.substring(0, len - 1);
};

// Clears the display
swisscalc.display.numericDisplay.prototype.clear = function() {
	this._display = "0";
};

// Returns _display as a numeric value
swisscalc.display.numericDisplay.prototype.getDisplayValue = function() {
	return parseFloat(this._display);
};

// Formats the value and sets the display. "val" should be a number.
swisscalc.display.numericDisplay.prototype.setDisplayValue = function(val) {
	// TODO: May need to do some formatting/rounding...
	this._display = val.toString();
};