Add Graph fragment

app/build.gradle

@@ -68,4 +68,5 @@ dependencies {
     implementation 'com.intuit.ssp:ssp-android:1.1.0'
 
     implementation 'org.jetbrains.kotlinx:kotlinx-serialization-json:1.5.0'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.4'
 }

app/src/main/java/com/fintamath/calculator/Approximator.kt

@@ -0,0 +1,16 @@
+package com.fintamath.calculator
+
+class Approximator {
+
+    external fun approximate(exprStr: String, varStr: String, valStr: String): String
+
+    external fun getVariableCount(exprStr: String): Int
+
+    external fun getLastVariable(exprStr: String): String
+
+    companion object {
+        init {
+            System.loadLibrary("fintamath_android")
+        }
+    }
+}

app/src/main/java/com/fintamath/calculator/Calculator.kt

@@ -16,6 +16,12 @@ internal class Calculator(
 
     external fun setPrecision(int: Int)
 
+    external fun approximate(exprStr: String, varStr: String, valStr: String): String
+
+    external fun getVariableCount(exprStr: String): Int
+
+    external fun getLastVariable(exprStr: String): String
+
     private fun onCalculated(str: String) {
         calculatedCallback.invoke(listOf(*str.split("\n").toTypedArray()))
     }

app/src/main/java/com/fintamath/calculator/CalculatorProcessor.kt

@@ -50,6 +50,13 @@ class CalculatorProcessor(
 
     fun setPrecision(precision: Int) = calculator.setPrecision(precision)
 
+    fun approximate(exprStr: String, varStr: String, valStr: String): String =
+        calculator.approximate(exprStr, varStr, valStr)
+
+    fun getVariableCount(exprStr: String): Int = calculator.getVariableCount(exprStr)
+
+    fun getLastVariable(exprStr: String): String = calculator.getLastVariable(exprStr)
+
     private fun onCalculated(result: List<String>) {
         callbacksThread {
             isCalculating.set(false)

app/src/main/java/com/fintamath/fragment/calculator/CalculatorFragment.kt

@@ -2,21 +2,27 @@ package com.fintamath.fragment.calculator
 
 import android.graphics.drawable.ColorDrawable
 import android.os.Bundle
+import android.util.Log
 import android.view.LayoutInflater
 import android.view.MotionEvent
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import androidx.lifecycle.lifecycleScope
 import androidx.navigation.findNavController
 import com.fintamath.R
 import com.fintamath.calculator.CalculatorProcessor
 import com.fintamath.databinding.FragmentCalculatorBinding
 import com.fintamath.storage.HistoryStorage
-import com.fintamath.storage.CalculatorInputStorage
+import com.fintamath.storage.CalculatorStorage
 import com.fintamath.storage.MathTextData
 import com.fintamath.storage.SettingsStorage
 import com.fintamath.widget.keyboard.Keyboard
 import com.fintamath.widget.keyboard.KeyboardView
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.yield
+import java.math.BigDecimal
 import java.util.Timer
 import java.util.TimerTask
 import java.util.concurrent.atomic.AtomicBoolean
@@ -41,6 +47,8 @@ class CalculatorFragment : Fragment() {
 
     private var wereSettingsUpdated = AtomicBoolean(false)
 
+    private var drawGraphJob: Job? = null
+
     private val maxSolutionLength = 2000
 
     private val inTextViewPreloadString = "abc * 123 Pi E I Inf ComplexInf () sqrt() abs() floor() ceil() derivative(x,x)"
@@ -78,8 +86,8 @@ class CalculatorFragment : Fragment() {
         updateSettings()
 
         if (inTextViewState.get() == InTextViewState.Ready.value) {
-            if (viewBinding.inTextView.text != CalculatorInputStorage.mathTextData.text) {
-                viewBinding.inTextView.text = CalculatorInputStorage.mathTextData.text
+            if (viewBinding.inTextView.text != CalculatorStorage.inputMathTextData.text) {
+                viewBinding.inTextView.text = CalculatorStorage.inputMathTextData.text
             }
 
             if (viewBinding.outSolutionView.isShowingLoading() || wereSettingsUpdated.get()) {
@@ -103,7 +111,7 @@ class CalculatorFragment : Fragment() {
     private fun initMathTexts() {
         viewBinding.inTextLayout.setOnTouchListener { _, event -> touchInText(event) }
 
-        viewBinding.inTextView.text = CalculatorInputStorage.mathTextData.text
+        viewBinding.inTextView.text = CalculatorStorage.inputMathTextData.text
         viewBinding.inTextView.setOnTextChangedListener { _, text -> onInTextChange(text) }
         viewBinding.inTextView.setOnFocusChangeListener { _, state -> onInTextFocusChange(state) }
     }
@@ -174,10 +182,11 @@ class CalculatorFragment : Fragment() {
     }
 
     private fun initBarButtons() {
-//        viewBinding.cameraButton.setOnClickListener { showCameraFragment() } // TODO: uncomment when camera is implemented
+        // viewBinding.cameraButton.setOnClickListener { showCameraFragment() } // TODO: uncomment when camera is implemented
         viewBinding.historyButton.setOnClickListener { showHistoryFragment() }
         viewBinding.settingsButton.setOnClickListener { showSettingsFragment() }
         viewBinding.aboutButton.setOnClickListener { showAboutFragment() }
+        viewBinding.graphButton.setOnClickListener { showGraphFragment() }
     }
 
     private fun updateSettings() {
@@ -206,7 +215,7 @@ class CalculatorFragment : Fragment() {
             }
         }
 
-        CalculatorInputStorage.mathTextData = MathTextData(text)
+        CalculatorStorage.inputMathTextData = MathTextData(text)
         cancelSaveToHistoryTask()
 
         viewBinding.inTextViewHint.visibility = if (viewBinding.inTextView.text.isNotEmpty())
@@ -245,6 +254,8 @@ class CalculatorFragment : Fragment() {
             viewBinding.outSolutionView.showFailedToSolve()
         } else {
             val cutSolutionTexts = cutSolutionTexts(texts)
+            val firstSolutionText = cutSolutionTexts.first()
+            CalculatorStorage.outputMathTextData.text = firstSolutionText
 
             if (countTextsLength(cutSolutionTexts) > maxSolutionLength) {
                 viewBinding.outSolutionView.showCharacterLimitExceeded()
@@ -314,6 +325,10 @@ class CalculatorFragment : Fragment() {
         showFragment(R.id.action_calculatorFragment_to_settingsFragment)
     }
 
+    private fun showGraphFragment() {
+        showFragment(R.id.action_calculatorFragment_to_graphFragment)
+    }
+
     private fun showFragment(navigationId: Int) {
         runSaveToHistoryTask()
         viewBinding.inTextView.clearFocusInWeb()

app/src/main/java/com/fintamath/fragment/graph/GraphFragment.kt

@@ -0,0 +1,161 @@
+package com.fintamath.fragment.graph
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.navigation.findNavController
+import com.fintamath.R
+import com.fintamath.calculator.Approximator
+import com.fintamath.databinding.FragmentGraphBinding
+import com.fintamath.storage.CalculatorStorage
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.yield
+import java.math.BigDecimal
+
+class GraphFragment : Fragment() {
+
+    private lateinit var viewBinding: FragmentGraphBinding
+    private lateinit var approximator: Approximator
+
+    private var currentMathText = CalculatorStorage.outputMathTextData.text
+
+    private val drawGraphScope = CoroutineScope(Job() + Dispatchers.Main)
+    private var drawGraphJob: Job? = null
+
+    private val initialMinX = BigDecimal(-10)
+    private val initialMaxX = BigDecimal(10)
+    private val graphPointNum = 200
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?,
+    ): View {
+        viewBinding = FragmentGraphBinding.inflate(inflater, container, false)
+
+        initBarButtons()
+        initApproximator()
+
+        viewBinding.graphView.setOnScrollOrScale {
+            if (currentMathText != CalculatorStorage.outputMathTextData.text) {
+                currentMathText = CalculatorStorage.outputMathTextData.text
+                viewBinding.graphView.clearGraph()
+            }
+
+            drawGraph(viewBinding.graphView.getMinX(), viewBinding.graphView.getMaxX())
+        }
+
+        drawGraph(initialMinX, initialMaxX)
+
+        return viewBinding.root
+    }
+
+    private fun initBarButtons() {
+        viewBinding.calculatorButton.setOnClickListener { showCalculatorFragment() }
+        viewBinding.historyButton.setOnClickListener { showHistoryFragment() }
+        // viewBinding.cameraButton.setOnClickListener { showCameraFragment() } // TODO: uncomment when camera is implemented{
+        viewBinding.settingsButton.setOnClickListener { showSettingsFragment() }
+        viewBinding.aboutButton.setOnClickListener { showAboutFragment() }
+    }
+
+    private fun initApproximator() {
+        approximator = Approximator()
+    }
+
+    private fun drawGraph(minX: BigDecimal, maxX: BigDecimal) {
+        drawGraph(CalculatorStorage.outputMathTextData.text, minX, maxX)
+    }
+
+    private fun drawGraph(firstSolutionText: String, min: BigDecimal, max: BigDecimal) {
+        drawGraphJob?.cancel()
+
+        drawGraphJob = drawGraphScope.launch {
+            if (approximator.getVariableCount(firstSolutionText) != 1) {
+                return@launch
+            }
+
+            val varName = approximator.getLastVariable(firstSolutionText)
+            val mid = (min + max).divide(BigDecimal(2))
+
+            drawGraphPoint(firstSolutionText, varName, mid)
+
+            val delta = (max - min).divide(BigDecimal(graphPointNum))
+            var bottom = mid - delta
+            var top = mid + delta
+
+            while (bottom >= min) {
+                yield()
+
+                drawGraphPoint(firstSolutionText, varName, bottom)
+                drawGraphPoint(firstSolutionText, varName, top)
+
+                bottom -= delta
+                top += delta
+            }
+        }
+    }
+
+    private fun drawGraphPoint(
+        firstSolutionText: String,
+        varName: String,
+        varValue: BigDecimal
+    ) {
+        if (viewBinding.graphView.hasPoint(varValue)) {
+            return
+        }
+
+        val approxValueStr = approximator.approximate(
+            firstSolutionText,
+            varName,
+            toFintamathReal(varValue)
+        )
+
+        if (approxValueStr.isEmpty()) {
+            return
+        }
+
+        viewBinding.graphView.addPoint(varValue, toBigDecimal(approxValueStr))
+    }
+
+    private fun toFintamathReal(bigDecimal: BigDecimal): String {
+        return bigDecimal.toString().replace("E", "*10^")
+    }
+
+    private fun toBigDecimal(fintamathReal: String): BigDecimal {
+        return BigDecimal(fintamathReal.replace("*10^", "E"))
+    }
+
+    private fun showCalculatorFragment() {
+        executeBack()
+    }
+
+    private fun showHistoryFragment() {
+        executeBack()
+        showFragment(R.id.action_calculatorFragment_to_historyFragment)
+    }
+
+    private fun showCameraFragment() {
+        executeBack()
+        showFragment(R.id.action_calculatorFragment_to_cameraFragment)
+    }
+
+    private fun showAboutFragment() {
+        showFragment(R.id.action_graphFragment_to_aboutFragment)
+    }
+
+    private fun showSettingsFragment() {
+        showFragment(R.id.action_graphFragment_to_settingsFragment)
+    }
+
+    private fun showFragment(navigationId: Int) {
+        viewBinding.root.findNavController().navigate(navigationId)
+    }
+
+    private fun executeBack() {
+        viewBinding.root.findNavController().navigateUp()
+    }
+}

app/src/main/java/com/fintamath/fragment/history/HistoryFragment.kt

@@ -13,10 +13,7 @@ import com.fintamath.R
 import com.fintamath.databinding.FragmentHistoryBinding
 import com.fintamath.storage.HistoryStorage
 import com.fintamath.storage.MathTextData
-import com.fintamath.storage.CalculatorInputStorage
-import java.util.Timer
-import java.util.TimerTask
-import kotlin.concurrent.schedule
+import com.fintamath.storage.CalculatorStorage
 
 class HistoryFragment : Fragment() {
 
@@ -52,7 +49,8 @@ class HistoryFragment : Fragment() {
 
     private fun initBarButtons() {
         viewBinding.calculatorButton.setOnClickListener { showCalculatorFragment() }
-//        viewBinding.cameraButton.setOnClickListener { showCameraFragment() } // TODO: uncomment when camera is implemented
+        viewBinding.graphButton.setOnClickListener { showGraphFragment() }
+        // viewBinding.cameraButton.setOnClickListener { showCameraFragment() } // TODO: uncomment when camera is implemented{
         viewBinding.settingsButton.setOnClickListener { showSettingsFragment() }
         viewBinding.aboutButton.setOnClickListener { showAboutFragment() }
     }
@@ -73,14 +71,19 @@ class HistoryFragment : Fragment() {
     }
 
     private fun onCalculate(text: String) {
-        CalculatorInputStorage.mathTextData = MathTextData(text)
+        CalculatorStorage.inputMathTextData = MathTextData(text)
         showCalculatorFragment()
     }
 
     private fun showCalculatorFragment() {
         executeBack()
     }
 
+    private fun showGraphFragment() {
+        executeBack()
+        showFragment(R.id.action_calculatorFragment_to_graphFragment)
+    }
+
     private fun showCameraFragment() {
         executeBack()
         showFragment(R.id.action_calculatorFragment_to_cameraFragment)

app/src/main/java/com/fintamath/storage/CalculatorStorage.kt

@@ -0,0 +1,6 @@
+package com.fintamath.storage
+
+object CalculatorStorage {
+    var inputMathTextData: MathTextData = MathTextData("")
+    var outputMathTextData: MathTextData = MathTextData("")
+}