Кастомный View для графика трат по категориям

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

@@ -2,10 +2,17 @@ package otus.homework.customview
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
 
 class MainActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+        val jsonString = resources.openRawResource(R.raw.payload)
+            .bufferedReader().use { it.readText() }
+        findViewById<PieChartView>(R.id.pieChart)
+            .setData(Gson().fromJson(jsonString,
+                object : TypeToken<List<Transaction>>() {}.type))
     }
 }

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

@@ -0,0 +1,221 @@
+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.graphics.Typeface
+import android.os.Parcel
+import android.os.Parcelable
+import android.util.AttributeSet
+import android.view.MotionEvent
+import android.view.View
+import androidx.core.content.ContextCompat
+import kotlin.math.roundToInt
+
+class PieChartView @JvmOverloads constructor(
+    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
+) : View(context, attrs, defStyleAttr) {
+
+    private var segments = listOf<SegmentData>()
+    private val colorResIds = intArrayOf(
+        R.color.lemon,
+        R.color.orange_900,
+        R.color.raspberry,
+        R.color.purple_200,
+        R.color.purple_500,
+        R.color.purple_700,
+        R.color.teal_200,
+        R.color.teal_700,
+        R.color.black,
+        R.color.white,
+    )
+    private val paint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.STROKE
+        strokeWidth = SEGMENT_HEIGHT
+        isAntiAlias = true
+    }
+    private val rectF = RectF()
+    var onSegmentClickListener: ((category: String) -> Unit)? = null
+    private var selectedCategory: String? = null
+    private var selectedAmount: String? = null
+    private var selectedPercent: String? = null
+    private val textPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        color = Color.BLACK
+        textSize = 40f
+        textAlign = Paint.Align.CENTER
+        typeface = Typeface.create(Typeface.DEFAULT, Typeface.BOLD)
+    }
+    override fun onSaveInstanceState(): Parcelable? {
+        val superState = super.onSaveInstanceState()
+        return SavedState(superState).apply {
+            this.sums = segments.map { it.amount }.toIntArray()
+            this.colors = segments.map { it.color }.toIntArray()
+            this.categories = segments.map { it.category }.toTypedArray()
+        }
+    }
+
+    override fun onRestoreInstanceState(state: Parcelable?) {
+        if (state is SavedState) {
+            super.onRestoreInstanceState(state.superState)
+            val sums = state.sums ?: intArrayOf()
+            val colors = state.colors ?: intArrayOf()
+            val cats = state.categories ?: arrayOf()
+            segments = sums.indices.map { i ->
+                SegmentData(sums[i], colors[i], cats.getOrElse(i) { "" })
+            }
+            invalidate()
+        } else {
+            super.onRestoreInstanceState(state)
+        }
+    }
+
+    fun setData(data: List<Transaction>) {
+        getCategoriesFromTransactions(data)
+        invalidate()
+    }
+
+    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
+        val wMode = MeasureSpec.getMode(widthMeasureSpec)
+        val hMode = MeasureSpec.getMode(heightMeasureSpec)
+        val wSize = MeasureSpec.getSize(widthMeasureSpec)
+        val hSize = MeasureSpec.getSize(heightMeasureSpec)
+        val displayMetrics = resources.displayMetrics
+        val screenWidth = displayMetrics.widthPixels
+        val screenHeight = displayMetrics.heightPixels
+        val optimalSize = (minOf(screenWidth, screenHeight) * CHART_PERCENT_OF_FULL_SIZE).toInt()
+        val width = when (wMode) {
+            MeasureSpec.EXACTLY -> wSize
+            MeasureSpec.AT_MOST -> minOf(optimalSize, wSize)
+            MeasureSpec.UNSPECIFIED -> optimalSize
+            else -> wSize
+        }
+        val height = when (hMode) {
+            MeasureSpec.EXACTLY -> hSize
+            MeasureSpec.AT_MOST -> minOf(optimalSize, hSize)
+            MeasureSpec.UNSPECIFIED -> optimalSize
+            else -> hSize
+        }
+        val finalSize = minOf(width, height)
+        setMeasuredDimension(finalSize, finalSize)
+    }
+
+    override fun onDraw(canvas: Canvas) {
+        super.onDraw(canvas)
+        if (segments.isEmpty()) return
+        val size = minOf(width, height).toFloat()
+        val offset = paint.strokeWidth / 2
+        rectF.set(offset, offset, size - offset, size - offset)
+        val total = segments.sumOf { it.amount }
+        if (total == 0) return
+        var startAngle = -90f
+        for (segment in segments) {
+            val currentAngle = (segment.amount.toFloat() / total) * 360f
+            paint.color = segment.color
+            canvas.drawArc(rectF, startAngle, currentAngle, false, paint)
+            startAngle += currentAngle
+        }
+        selectedCategory?.let { category ->
+            val centerX = width / 2f
+            val centerY = height / 2f
+            val lineSpacing = CLICKED_INFO_LIMES_PACING
+            canvas.drawText(category, centerX, centerY - lineSpacing, textPaint)
+            var amountPercentText = selectedAmount.orEmpty()
+            if (!selectedPercent.isNullOrEmpty()) {
+                amountPercentText += " - $selectedPercent%"
+            }
+            canvas.drawText(amountPercentText, centerX, centerY + textPaint.textSize, textPaint)
+        }
+    }
+
+    fun getCategoriesFromTransactions(transactions: List<Transaction>) {
+        val grouped = transactions.groupBy { it.category }
+        segments = grouped.entries.mapIndexed { index, entry ->
+            val sum = entry.value.sumOf { it.amount }
+            val resId = colorResIds.getOrElse(index % colorResIds.size) { Color.WHITE }
+            val color = ContextCompat.getColor(context, resId)
+            SegmentData(
+                amount = sum,
+                color = color,
+                category = entry.key
+            )
+        }
+        invalidate()
+    }
+
+    override fun onTouchEvent(event: MotionEvent): Boolean {
+        if (event.action == MotionEvent.ACTION_DOWN) {
+            val centerX = width / 2f
+            val centerY = height / 2f
+            val dx = event.x - centerX
+            val dy = event.y - centerY
+            val distance = Math.hypot(dx.toDouble(), dy.toDouble()).toFloat()
+            val outerRadius = rectF.width() / 2 + paint.strokeWidth / 2
+            val innerRadius = rectF.width() / 2 - paint.strokeWidth / 2
+            if (distance !in innerRadius..outerRadius) {
+                return false
+            }
+            val rawAngle = Math.toDegrees(Math.atan2(dy.toDouble(), dx.toDouble())).toFloat()
+            val angle = (rawAngle + 360) % 360
+            val segmentAngle = (angle + 90 + 360) % 360
+            val total = segments.sumOf { it.amount.toLong() }.toFloat()
+            if (total > 0f) {
+                var currentAngle = 0f
+                for (segment in segments) {
+                    val currentPercent = segment.amount.toFloat() / total
+                    val segmentAngel = currentPercent * 360f
+                    if (segmentAngle >= currentAngle && segmentAngle < (currentAngle + segmentAngel)) {
+                        selectedCategory = segment.category
+                        selectedAmount = segment.amount.toString()
+                        selectedPercent = (currentPercent * 100).roundToInt().toString()
+                        invalidate()
+                        onSegmentClickListener?.invoke(segment.category)
+                        performClick()
+                        return true
+                    }
+                    currentAngle += segmentAngel
+                }
+            }
+        }
+        return true
+    }
+
+    override fun performClick(): Boolean {
+        return super.performClick()
+    }
+    private companion object {
+        const val SEGMENT_HEIGHT = 140f
+        const val CHART_PERCENT_OF_FULL_SIZE = 0.6f
+        const val CLICKED_INFO_LIMES_PACING = 10f
+    }
+
+    private class SavedState : BaseSavedState {
+        var sums: IntArray? = null
+        var colors: IntArray? = null
+        var categories: Array<String>? = null
+
+        constructor(superState: Parcelable?) : super(superState)
+        constructor(source: Parcel) : super(source) {
+            sums = source.createIntArray()
+            colors = source.createIntArray()
+            categories = source.createStringArray()
+        }
+
+        override fun writeToParcel(out: Parcel, flags: Int) {
+            super.writeToParcel(out, flags)
+            out.writeIntArray(sums)
+            out.writeIntArray(colors)
+            out.writeStringArray(categories)
+        }
+
+        companion object {
+            @JvmField
+            val CREATOR = object : Parcelable.Creator<SavedState> {
+                override fun createFromParcel(source: Parcel) = SavedState(source)
+                override fun newArray(size: Int) = arrayOfNulls<SavedState>(size)
+            }
+        }
+    }
+
+}

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

@@ -0,0 +1,7 @@
+package otus.homework.customview
+
+internal data class SegmentData(
+    val amount: Int,
+    val color: Int,
+    val category: String
+)

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

@@ -0,0 +1,9 @@
+package otus.homework.customview
+
+data class Transaction(
+    val id: Int,
+    val name: String,
+    val amount: Int,
+    val category: String,
+    val time: Long
+)

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

@@ -7,13 +7,14 @@
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
-    <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" />
+    <otus.homework.customview.PieChartView
+        android:id="@+id/pieChart"
+        android:layout_width="300dp"
+        android:layout_height="300dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"/>
+
 
 </androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -1,5 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
+    <color name="lemon">#FFF176</color>
+    <color name="orange_900">#E65100</color>
+    <color name="raspberry">#DC143C</color>
     <color name="purple_200">#FFBB86FC</color>
     <color name="purple_500">#FF6200EE</color>
     <color name="purple_700">#FF3700B3</color>