Fraction output

app/src/androidTest/java/com/darkempire78/opencalculator/FractionTests.kt

@@ -0,0 +1,48 @@
+package com.darkempire78.opencalculator
+
+import android.content.Context
+import android.widget.TextView
+import androidx.test.core.app.ApplicationProvider
+import com.darkempire78.opencalculator.calculator.decimalToFraction
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class FractionTests {
+    val context: Context = ApplicationProvider.getApplicationContext()
+    val view = TextView(context)
+
+    @Test
+    fun testFraction(){
+        val dec = "4.563"
+        decimalToFraction(dec, 1.0E-4, view)
+        assertEquals("4 67/119", view.text.toString())
+    }
+
+    @Test
+    fun testLessThanOneWithZero(){
+        val dec = "0.345"
+        decimalToFraction(dec, 1.0E-4, view)
+        assertEquals("69/200", view.text.toString())
+    }
+
+    @Test
+    fun testLessThanOneWithoutZero(){
+        val dec = ".345"
+        decimalToFraction(dec, 1.0E-4, view)
+        assertEquals("69/200", view.text.toString())
+    }
+
+    @Test
+    fun testRepeatDecimalRounding(){
+        val dec = "3.33333"
+        decimalToFraction(dec, 1.0E-4, view)
+        assertEquals("3 1/3", view.text.toString())
+    }
+
+    @Test
+    fun testRepeatDecimalNoRounding(){
+        val dec = "3.33333"
+        decimalToFraction(dec, 1.0E-5, view)
+        assertEquals("3 33333/100000", view.text.toString())
+    }
+}

app/src/main/java/com/darkempire78/opencalculator/MyPreferences.kt

@@ -28,6 +28,8 @@ class MyPreferences(context: Context) {
         private const val KEY_SPLIT_PARENTHESIS_BUTTON = "darkempire78.opencalculator.SPLIT_PARENTHESIS_BUTTON"
         private const val KEY_DELETE_HISTORY_ON_SWIPE = "darkempire78.opencalculator.DELETE_HISTORY_ELEMENT_ON_SWIPE"
         private const val KEY_AUTO_SAVE_CALCULATION_WITHOUT_EQUAL_BUTTON = "darkempire78.opencalculator.AUTO_SAVE_CALCULATION_WITHOUT_EQUAL_BUTTON"
+        private const val KEY_SHOW_FRACTION = "darkempire78.opencalculator.SHOW_FRACTION"
+        private const val KEY_FRACTION_PRECISION = "darkempire78.opencalculator.FRACTION_PRECISION"
         private const val KEY_NUMBERING_SYSTEM = "darkempire78.opencalculator.NUMBERING_SYSTEM"
         private const val KEY_SHOW_ON_LOCK_SCREEN = "darkempire78.opencalculator.KEY_SHOW_ON_LOCK_SCREEN"
     }
@@ -68,6 +70,10 @@ class MyPreferences(context: Context) {
     var autoSaveCalculationWithoutEqualButton = preferences.getBoolean(KEY_AUTO_SAVE_CALCULATION_WITHOUT_EQUAL_BUTTON, true)
         set(value) = preferences.edit().putBoolean(KEY_AUTO_SAVE_CALCULATION_WITHOUT_EQUAL_BUTTON, value).apply()
 
+    var showResultFraction = preferences.getBoolean(KEY_SHOW_FRACTION, false)
+        set(value) = preferences.edit().putBoolean(KEY_SHOW_FRACTION, value).apply()
+    var fractionPrecision = preferences.getString(KEY_FRACTION_PRECISION, "4")
+        set(value) = preferences.edit().putString(KEY_FRACTION_PRECISION, value).apply()
     var numberingSystem = preferences.getInt(KEY_NUMBERING_SYSTEM, 0)
         set(value) = preferences.edit().putInt(KEY_NUMBERING_SYSTEM, value).apply()
 

app/src/main/java/com/darkempire78/opencalculator/activities/MainActivity.kt

@@ -11,14 +11,14 @@ import android.os.Build
 import android.os.Bundle
 import android.text.Editable
 import android.text.TextWatcher
-import android.util.Log
 import android.view.HapticFeedbackConstants
 import android.view.MenuItem
 import android.view.View
 import android.view.WindowManager
 import android.view.accessibility.AccessibilityEvent
 import android.widget.Button
 import android.widget.HorizontalScrollView
+import android.widget.TextView
 import android.widget.Toast
 import androidx.activity.addCallback
 import androidx.appcompat.app.AppCompatActivity
@@ -34,6 +34,7 @@ import com.darkempire78.opencalculator.R
 import com.darkempire78.opencalculator.TextSizeAdjuster
 import com.darkempire78.opencalculator.Themes
 import com.darkempire78.opencalculator.calculator.Calculator
+import com.darkempire78.opencalculator.calculator.decimalToFraction
 import com.darkempire78.opencalculator.calculator.division_by_0
 import com.darkempire78.opencalculator.calculator.domain_error
 import com.darkempire78.opencalculator.calculator.is_infinity
@@ -79,6 +80,7 @@ class MainActivity : AppCompatActivity() {
     private var isEqualLastAction = false
     private var isDegreeModeActivated = true // Set degree by default
     private var errorStatusOld = false
+    private var showFraction = false // default
 
     private var isStillTheSameCalculation_autoSaveCalculationWithoutEqualOption = false
     private var lastHistoryElementId = ""
@@ -431,6 +433,11 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    private  fun getFractionPrecision(): String {
+        val fractionPrecision = MyPreferences(this).fractionPrecision
+        return fractionPrecision.toString()
+    }
+
     private fun setErrorColor(errorStatus: Boolean) {
         // Only run if the color needs to be updated
         runOnUiThread {
@@ -644,14 +651,6 @@ class MainActivity : AppCompatActivity() {
                         }
                     }
 
-                    withContext(Dispatchers.Main) {
-                        if (formattedResult != calculation) {
-                            binding.resultDisplay.text = formattedResult
-                        } else {
-                            binding.resultDisplay.text = ""
-                        }
-                    }
-
                     // Save to history if the option autoSaveCalculationWithoutEqualButton is enabled
                     if (MyPreferences(this@MainActivity).autoSaveCalculationWithoutEqualButton) {
                         if (calculation != formattedResult) {
@@ -1041,7 +1040,14 @@ class MainActivity : AppCompatActivity() {
                     }
 
                     // Display result
-                    withContext(Dispatchers.Main) { binding.input.setText(formattedResult) }
+                    withContext(Dispatchers.Main) {
+                        binding.input.setText(formattedResult)
+                        if (showFraction && '.' in formattedResult) {
+                            val tView = findViewById<TextView>(R.id.resultDisplay)
+                            val precision = getFractionPrecision().toDouble()
+                            decimalToFraction(formattedResult, precision, tView)
+                        }
+                    }
 
                     // Set cursor
                     withContext(Dispatchers.Main) {
@@ -1052,7 +1058,9 @@ class MainActivity : AppCompatActivity() {
                         binding.input.isCursorVisible = false
 
                         // Clear resultDisplay
-                        binding.resultDisplay.text = ""
+                        if (!showFraction) {
+                            binding.resultDisplay.text = ""
+                        }
                     }
 
                     if (calculation != formattedResult) {
@@ -1295,6 +1303,14 @@ class MainActivity : AppCompatActivity() {
             updateInputDisplay()
         }
 
+        // Show result fractions if enabled
+        if (MyPreferences(this).showResultFraction) {
+            showFraction = true
+        } else {
+            showFraction = false
+        }
+
+
         // Split the parentheses button (if option is enabled)
         if (MyPreferences(this).splitParenthesisButton) {
             // Hide the AC button

app/src/main/java/com/darkempire78/opencalculator/calculator/Fraction.kt

@@ -0,0 +1,63 @@
+package com.darkempire78.opencalculator.calculator
+
+import android.text.Spannable
+import android.text.SpannableStringBuilder
+import android.text.style.RelativeSizeSpan
+import android.text.style.SuperscriptSpan
+import android.widget.TextView
+import kotlin.math.abs
+import kotlin.math.floor
+
+fun decimalToFraction(calculation: String, precision: Double, textView: TextView) {
+
+    val decimalPosition = calculation.indexOf('.')
+    var decimal = calculation.substring(decimalPosition).toDouble()
+    val whole = if (decimalPosition > 0) calculation.substring(0, decimalPosition).toInt() else 0
+
+    var n1 = 1
+    var n2 = 0
+    var d1 = 0
+    var d2 = 1
+
+    var dec = decimal // - base.toDouble()
+    val dec2 = decimal
+
+    do {
+        val a = floor(dec).toInt()
+        val numer = n1
+        val denom = d1
+        n1 = a * n1 + n2
+        n2 = numer
+        d1 = a * d1 + d2
+        d2 = denom
+        dec = 1 / (dec - a)
+    } while (abs(dec2 - n1.toDouble() / d1) > dec2 * precision)
+
+    if (whole != 0) {
+        if (n1 == 0) {
+            textView.text = whole.toString()
+        } else {
+            val tempString = "$whole $n1/$d1"
+            val stringSpan = SpannableStringBuilder(tempString)
+            val spaceLoc = stringSpan.indexOf(' ')
+            val stringLen = stringSpan.length
+            stringSpan.setSpan(
+                SuperscriptSpan(),
+                spaceLoc,
+                stringLen,
+                Spannable.SPAN_EXCLUSIVE_EXCLUSIVE
+            )
+            stringSpan.setSpan(
+                RelativeSizeSpan(0.6f),
+                spaceLoc,
+                stringLen,
+                Spannable.SPAN_EXCLUSIVE_EXCLUSIVE
+            )
+            textView.text = stringSpan
+        }
+    } else {
+        val tempString = "$n1/$d1"
+        val stringSpan = SpannableStringBuilder(tempString)
+        textView.text = stringSpan
+    }
+}

app/src/main/res/drawable/fracprec.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="960"
+    android:viewportHeight="960">
+  <path
+      android:pathData="m720,880 l-56,-56 63,-64L480,760v-80h247l-63,-64 56,-56 160,160L720,880ZM80,520v-120h120v120L80,520ZM380,520q-58,0 -99,-41t-41,-99v-160q0,-58 41,-99t99,-41q58,0 99,41t41,99v160q0,58 -41,99t-99,41ZM740,520q-58,0 -99,-41t-41,-99v-160q0,-58 41,-99t99,-41q58,0 99,41t41,99v160q0,58 -41,99t-99,41ZM380,440q25,0 42.5,-17.5T440,380v-160q0,-25 -17.5,-42.5T380,160q-25,0 -42.5,17.5T320,220v160q0,25 17.5,42.5T380,440ZM740,440q25,0 42.5,-17.5T800,380v-160q0,-25 -17.5,-42.5T740,160q-25,0 -42.5,17.5T680,220v160q0,25 17.5,42.5T740,440Z"
+      android:fillColor="#1f1f1f"/>
+</vector>

app/src/main/res/drawable/ftfrac.xml

@@ -0,0 +1,8 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:viewportHeight="60" android:viewportWidth="60" android:width="24dp">
+
+    <path android:fillColor="#333333" android:pathData="m11.333,16.946l4.625,-4.983 -2.806,-3.026c-0.679,-0.725 -1.137,-1.218 -1.375,-1.479 -0.229,-0.272 -0.403,-0.538 -0.528,-0.799 -0.125,-0.272 -0.186,-0.578 -0.186,-0.918 0,-0.816 0.264,-1.49 0.798,-2.023 0.531,-0.532 1.134,-0.799 1.802,-0.799 0.647,0 1.155,0.091 1.529,0.272s0.76,0.533 1.158,1.054l2.89,3.621 2.89,-3.621c0.418,-0.521 0.809,-0.873 1.172,-1.054s0.868,-0.272 1.515,-0.272c0.667,0 1.268,0.261 1.802,0.782 0.531,0.521 0.798,1.201 0.798,2.04 0,0.34 -0.061,0.646 -0.186,0.918 -0.125,0.261 -0.308,0.527 -0.545,0.799 -0.226,0.261 -0.679,0.754 -1.358,1.479l-2.806,3.026 4.622,4.983c0.296,0.316 0.545,0.662 0.749,1.036 0.218,0.363 0.325,0.792 0.325,1.291 0,0.827 -0.267,1.497 -0.801,2.008 -0.531,0.499 -1.19,0.746 -1.97,0.746 -0.511,0 -0.931,-0.107 -1.259,-0.322 -0.316,-0.215 -0.702,-0.572 -1.155,-1.071l-3.792,-4.488 -3.792,4.488c-0.395,0.453 -0.769,0.798 -1.12,1.036 -0.354,0.238 -0.783,0.357 -1.294,0.357 -0.78,0 -1.439,-0.247 -1.97,-0.746 -0.534,-0.511 -0.801,-1.181 -0.801,-2.008 0,-0.487 0.09,-0.899 0.273,-1.239 0.191,-0.342 0.458,-0.705 0.798,-1.088z"/>
+
+    <path android:fillColor="#333333" android:pathData="m35.093,52.176l1.819,-4.132 -4.622,-11.15c-0.772,-1.793 -1.157,-2.93 -1.157,-3.418 0,-0.76 0.261,-1.372 0.782,-1.837 0.532,-0.464 1.156,-0.696 1.87,-0.696 1.338,0 2.26,0.685 2.771,2.057l3.215,8.382 3.026,-7.483c0.429,-0.995 0.859,-1.738 1.291,-2.225 0.429,-0.487 0.986,-0.731 1.665,-0.731 0.827,0 1.497,0.25 2.008,0.749 0.519,0.487 0.78,1.155 0.78,2.005 0,0.577 -0.221,1.378 -0.662,2.397l-8.043,18.94c-0.386,0.917 -0.766,1.581 -1.14,1.987 -0.363,0.421 -0.966,0.63 -1.816,0.63 -0.873,0 -1.544,-0.267 -2.008,-0.798 -0.453,-0.534 -0.679,-1.085 -0.679,-1.651 0,-0.453 0.055,-0.862 0.168,-1.224 0.125,-0.363 0.368,-0.963 0.731,-1.802z"/>
+
+    <path android:fillColor="#00000000" android:pathData="m12.419,36.375l35.38,-20.835" android:strokeColor="#333333" android:strokeLineCap="round" android:strokeLineJoin="round" android:strokeWidth="5"/>
+</vector>

app/src/main/res/values/arrays.xml

@@ -86,4 +86,28 @@
         <item>1000</item> <!-- Infinity -->
     </string-array>
 
+    <string-array name="fraction_precision_entries">
+        <item>2</item>
+        <item>3</item>
+        <item>4</item>
+        <item>5</item>
+        <item>6</item>
+        <item>7</item>
+        <item>8</item>
+        <item>9</item>
+        <item>10</item>
+    </string-array>
+
+    <string-array name="fraction_precision_values">
+        <item>1.0E-2</item>
+        <item>1.0E-3</item>
+        <item>1.0E-4</item>
+        <item>1.0E-5</item>
+        <item>1.0E-6</item>
+        <item>1.0E-7</item>
+        <item>1.0E-8</item>
+        <item>1.0E-9</item>
+        <item>1.0E-10</item>
+    </string-array>
+
 </resources>

app/src/main/res/values/strings.xml

@@ -84,6 +84,7 @@
     <string name="settings_category_formatting">FORMATTING</string>
     <string name="settings_category_history">HISTORY</string>
     <string name="settings_category_advanced">ADVANCED</string>
+    <string name="settings_category_fractions">FRACTIONS</string>
 
     <string name="settings_general_language">Language</string>
 
@@ -122,6 +123,11 @@
     <string name="settings_advanced_prevent_sleep">Keep device awake</string>
     <string name="settings_advanced_prevent_sleep_desc">Prevent device from sleeping while the app is in the foreground</string>
 
+    <string name="settings_fractions_use">Show Fractions</string>
+    <string name="settings_fractions_use_desc">Display results as fractions as well as decimals</string>
+    <string name="settings_fractions_precision">Fraction precision</string>
+    <string name="settings_fractions_precision_desc">How many decimal places before rounding occurs. Anything over will result in fraction rounding</string>
+
     <!-- About page -->
     <string name="about_category_help">HELP US</string>
     <string name="about_category_social">SOCIAL</string>

app/src/main/res/xml/root_preferences.xml

@@ -105,6 +105,25 @@
 
     </PreferenceCategory>
 
+    <PreferenceCategory
+        app:title="@string/settings_category_fractions">
+
+        <SwitchPreferenceCompat
+            app:defaultValue="false"
+            app:icon="@drawable/ftfrac"
+            app:key="darkempire78.opencalculator.SHOW_FRACTION"
+            app:summary="@string/settings_fractions_use_desc"
+            app:title="@string/settings_fractions_use"
+            app:widgetLayout="@drawable/material_switch" />
+        <ListPreference
+            app:defaultValue="2"
+            app:entries="@array/fraction_precision_entries"
+            app:entryValues="@array/fraction_precision_values"
+            app:icon="@drawable/fracprec"
+            app:key="darkempire78.opencalculator.FRACTION_PRECISION"
+            app:summary="@string/settings_fractions_precision_desc"
+            app:title="@string/settings_fractions_precision" />
+    </PreferenceCategory>
     <PreferenceCategory
         app:title="@string/settings_category_formatting"
         app:color="?attr/text_color">