adam-zielonka / unit-converter

Unit Converter

Table of contents

• Project structure
• Measure File Format
  • Properties
  • Equations
• Screens
• License
• Legal attribution

Project structure

• app - contain base code
• file - android library for internal/external file operations
• items - android library that contain ItemsView
• java - java library that contain supporting code
• verification - java library that support code to make interface to verify objects

Measure File Format

To add custom measures you can use editor build in app or you can prepare the json file:

{
  "name": {
    "en": "Area",
    "pl": "Powierzchnia"
  },
  "version": 1,
  "author": [
    "root"
  ],
  "global": "en",
  "units": [
    {
      "symbol": "m²",
      "descriptionPrefix": {
        "en": "square ",
        "pl": ""
      },
      "description": {
        "en": "meter",
        "pl": "metr kwadratowy"
      },
      "one": 1,
      "prefixes": [
        {
          "symbol": "k",
          "description": {
            "en": "kilo"
          },
          "exp": 6,
          "position": 3
        },
        {
          "symbol": "d",
          "description": {
            "en": "deci",
            "pl": "decy"
          },
          "exp": -2
        },
        {
          "symbol": "c",
          "description": {
            "en": "centi",
            "pl": "centy"
          },
          "": -4
        },
      ]
    },
    {
      "symbol": "in²",
      "description": {
        "en": "square inch",
        "pl": "cal kwadratowy"
      },
      "one": 0.00064516
    }
  ]
}

You can find more measures files on this folder: ./app/src/main/assets/converters

Properties

property	value
file	{name, version, author, global, units}
name	{"country_code" : "measure name"}
version	integer
author	["author name"]
global	base country code name
units	[{symbol, descriptionPrefix, description, one, shift, shift2, expBase, prefixes}]
symbol	base unit symbol
descriptionPrefix	{"country_code" : "description prefix"}
description	{"country_code" : "description"}
one	number of multiples of base unit, default is 1
shift	number of shift to the basic unit, default is 0
shift2	number of shift to the basic unit, default is 0
expBase	exponent base for prefixes, default is 10
prefixes	[{symbol, description, exp}]
symbol	prefix symbol
description	{"country_code" : "prefix description"}
exp	prefix exponent

Equations

In the file you define parameters for the equation that calculate target unit value from base unit:

$$ y = \alpha * (x + \Delta_1) + \Delta_2 $$

where:

• $x$ - value of base unit
• $y$ - value of target unit
• $\alpha$ - one - multiply of base value
• $\Delta_1$ - shift_1 - shift base value before multiply
• $\Delta_2$ - shift_2 - shift base value after multiply

For calculate base unit value form target unit, the equation is:

$$ x = \frac{1}{\alpha} * (y - \Delta_2) - \Delta_1 $$

To calculate from one unit to another, it used this formula:

$$ f(x) = \frac{1}{\alpha^T} * (\alpha^S * (x + \Delta_1^S) + \Delta_2^S - \Delta_2^T) - \Delta_1^T $$

where:

• $x$ - value of source unit
• $f(x)$ - value of target unit
• $\alpha^S$ - one from source unit
• $\Delta_1^S$ - shift_1 from source unit
• $\Delta_2^S$ - shift_2 from source unit
• $\alpha^T$ - one from target unit
• $\Delta_1^T$ - shift_1 from target unit
• $\Delta_2^T$ - shift_2 from target unit

Screens

License

MIT

Legal attribution

Google Play and the Google Play logo are trademarks of Google LLC.