Canvas homework

app/build.gradle

@@ -54,4 +54,5 @@ dependencies {
     testImplementation libs.junit
     androidTestImplementation libs.androidx.test.ext.junit
     androidTestImplementation libs.espresso.core
+    implementation("com.google.code.gson:gson:2.11.0")
 }

app/src/main/java/otus/homework/customview/CategoryModel.kt

@@ -0,0 +1,11 @@
+package otus.homework.customview
+
+import java.io.Serializable
+
+
+data class CategoryModel(
+    val id: Int,
+    val name: String,
+    val amount: Int,
+    val category: String,
+) : Serializable

app/src/main/java/otus/homework/customview/MainActivity.kt

@@ -2,10 +2,25 @@ package otus.homework.customview
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import android.widget.TextView
+import androidx.activity.viewModels
 
 class MainActivity : AppCompatActivity() {
+    private val viewModel: PieViewModel by viewModels {
+        PieViewModelFactory(context = this)
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+        val pieChartView = findViewById<PieChart>(R.id.pieChartView)
+        val contentNameTextView = findViewById<TextView>(R.id.categoryName)
+
+        val data = viewModel.data
+        pieChartView.onSliceClick = { categoryName ->
+            contentNameTextView.text = categoryName
+        }
+
+        pieChartView.setData(data)
     }
 }

app/src/main/java/otus/homework/customview/PieChart.kt

@@ -0,0 +1,166 @@
+package otus.homework.customview
+
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.graphics.RectF
+import android.os.Bundle
+import android.os.Parcelable
+import android.util.AttributeSet
+import android.view.MotionEvent
+import android.view.View
+import kotlin.math.atan2
+import kotlin.math.sqrt
+
+class PieChart @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null,
+    var onSliceClick: ((String) -> Unit)? = null
+): View(context, attrs) {
+
+    val Int.dp: Float
+        get() = this * resources.displayMetrics.density
+
+    private var data: Map<String, List<CategoryModel>> = emptyMap()
+    private val sectors = mutableListOf<Sector>()
+    private lateinit var rect: RectF
+
+    fun setData(items: Map<String, List<CategoryModel>>) {
+        data = items
+        calculateSectors()
+        invalidate()
+    }
+
+    init{
+        if (isInEditMode) {
+            //setValues(listOf(1,2,3,4,5))
+        }
+    }
+
+    override fun onSaveInstanceState(): Parcelable? {
+        val superState = super.onSaveInstanceState()
+
+        val bundle = Bundle()
+        bundle.putParcelable("super_state", superState)
+        bundle.putSerializable(STATE_DATE, HashMap(data))
+        return bundle
+    }
+
+    override fun onRestoreInstanceState(state: Parcelable?) {
+        if (state is Bundle) {
+            val superState = state.getParcelable<Parcelable>("super_state")
+            super.onRestoreInstanceState(superState)
+
+            data = state.getSerializable("data") as HashMap<String, List<CategoryModel>>
+            invalidate()
+        } else {
+            super.onRestoreInstanceState(state)
+        }
+    }
+
+    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
+        val width = MeasureSpec.getSize(widthMeasureSpec)
+        val height = MeasureSpec.getSize(heightMeasureSpec)
+
+        setMeasuredDimension(width, height)
+    }
+
+    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
+        super.onSizeChanged(w, h, oldw, oldh)
+
+        val size = minOf(w, h).toFloat()
+
+        val left = (w - size) / 2f
+        val top = (h - size) / 2f
+
+        rect = RectF(left, top, left + size, top + size)
+    }
+
+    val paint = Paint().apply {
+        style = Paint.Style.FILL
+    }
+
+    override fun onDraw(canvas: Canvas) {
+        super.onDraw(canvas)
+
+        if (sectors.isEmpty()) return
+
+        sectors.forEach {
+            paint.color = randomColor()
+
+            canvas.drawArc(
+                rect,
+                it.start,
+                it.end - it.start,
+                true,
+                paint
+            )
+        }
+    }
+
+    override fun onTouchEvent(event: MotionEvent): Boolean {
+
+        if (event.action != MotionEvent.ACTION_DOWN) return true
+
+        val dx = event.x - rect.centerX()
+        val dy = event.y - rect.centerY()
+
+        val distance = sqrt(dx * dx + dy * dy)
+
+        if (distance > rect.width() / 2f) return true
+
+        val angle = ((Math.toDegrees(
+            atan2(dy.toDouble(), dx.toDouble())
+        ) + 360) % 360).toFloat()
+
+        sectors.forEach { sector ->
+            if (angle in sector.start..sector.end) {
+                onSliceClick?.invoke(sector.category)
+                return true
+            }
+        }
+        return true
+    }
+
+    private fun randomColor(): Int {
+        return Color.rgb(
+            (0..255).random(),
+            (0..255).random(),
+            (0..255).random(),
+        )
+    }
+
+    private fun calculateSectors() {
+        sectors.clear()
+
+        val total = data.values.sumOf { list ->
+            list.sumOf { it.amount }
+        }.toFloat()
+
+        var startAngle = 0f
+
+        data.forEach { (category, items) ->
+            val amount = items.sumOf { it.amount }.toFloat()
+
+            val sweep =
+                if (amount != 0f) {
+                    (amount / total) * 360f
+                } else 0f
+
+            sectors.add(
+                Sector(
+                    category = category,
+                    start = startAngle,
+                    end = startAngle + sweep
+                )
+            )
+
+            startAngle += sweep
+        }
+    }
+
+    companion object {
+        private const val STATE_DATE = "data"
+    }
+}

app/src/main/java/otus/homework/customview/PieViewModel.kt

@@ -0,0 +1,30 @@
+package otus.homework.customview
+
+import android.content.Context
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import otus.homework.customview.data.JsonMapper
+
+class PieViewModel(
+    private val jsonMapper: JsonMapper
+) : ViewModel() {
+
+    val data = jsonMapper.mapJson()
+        .map {
+            CategoryModel(
+                id = it.id,
+                name = it.name,
+                amount = it.amount,
+                category = it.category,
+            )
+        }.groupBy { it.category }
+}
+
+class PieViewModelFactory(
+    private val context: Context
+) : ViewModelProvider.NewInstanceFactory() {
+    override fun <T : ViewModel> create(modelClass: Class<T>): T {
+        val jsonMapper = JsonMapper(context.applicationContext)
+        return PieViewModel(jsonMapper) as T
+    }
+}

app/src/main/java/otus/homework/customview/Sector.kt

@@ -0,0 +1,7 @@
+package otus.homework.customview
+
+data class Sector(
+    val category: String,
+    val start: Float,
+    val end: Float
+)

app/src/main/java/otus/homework/customview/data/JsonMapper.kt

@@ -0,0 +1,20 @@
+package otus.homework.customview.data
+
+import android.content.Context
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import otus.homework.customview.R
+import otus.homework.customview.dto.CategoryDTO
+
+class JsonMapper(private val context: Context) {
+
+    fun mapJson(): List<CategoryDTO> {
+        val json = context.resources
+            .openRawResource(R.raw.payload)
+            .bufferedReader()
+            .use { it.readText() }
+
+        val type = object : TypeToken<List<CategoryDTO>>() {}.type
+        return Gson().fromJson(json, type)
+    }
+}

app/src/main/java/otus/homework/customview/dto/CategoryDTO.kt

@@ -0,0 +1,8 @@
+package otus.homework.customview.dto
+
+data class CategoryDTO(
+    val id: Int,
+    val name: String,
+    val amount: Int,
+    val category: String,
+)

app/src/main/res/layout/activity_main.xml

@@ -1,19 +1,21 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout
+<LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:orientation="vertical"
     tools:context=".MainActivity">
 
+    <otus.homework.customview.PieChart
+        android:id="@+id/pieChartView"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"/>
+
     <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintLeft_toLeftOf="parent"
-        app:layout_constraintRight_toRightOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        android:id="@+id/categoryName"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"/>
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+</LinearLayout>