val x = leftPadding + i * (timeSpanPerTick / timeSpan) * viewWidth
canvas.drawLine(x, 0f, x, headerHeight, axisPaint)
canvas.drawText(formatTime(minTime + i * timeSpanPerTick), x, textY, textPaint)

// ---------------- 文件: build.gradle (Module) ----------------
/*
plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-kapt'
}
android {
    compileSdkVersion 34
    defaultConfig {
        applicationId "com.example.gantt"
        minSdkVersion 21
        targetSdkVersion 34
        versionCode 1
        versionName "1.0"
    }
    buildFeatures { viewBinding true }
}
dependencies {
    implementation "androidx.core:core-ktx:1.10.1"
    implementation "androidx.appcompat:appcompat:1.7.0"
    implementation "com.google.android.material:material:1.9.0"
    implementation "androidx.constraintlayout:constraintlayout:2.1.4"
    implementation "androidx.recyclerview:recyclerview:1.3.1"
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.6.1"
    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.6.1"
    implementation "androidx.room:room-runtime:2.5.2"
    kapt "androidx.room:room-compiler:2.5.2"
    implementation "org.threeten:threetenbp:1.6.0" // 或 ThreeTenABP
    implementation "com.jakewharton.threetenabp:threetenabp:1.4.4"
}
*/
 
// ---------------- 文件: Task.kt ----------------
package com.example.gantt.data
 
import androidx.room.Entity
import androidx.room.PrimaryKey
import org.threeten.bp.Instant
import org.threeten.bp.ZonedDateTime
 
/**
 * Task：Room 實體，表示甘特圖中的一個任務(wù)
 */
@Entity(tableName = "tasks")
data class Task(
    @PrimaryKey(autoGenerate = true) val id: Long = 0,
    val name: String,
    val startTime: Long, // 毫秒時間戳
    val endTime: Long,
    val color: Int // ARGB 顏色
)
 
// ---------------- 文件: TaskDao.kt ----------------
package com.example.gantt.data
 
import androidx.lifecycle.LiveData
import androidx.room.*
 
/**
 * TaskDao：任務(wù)增刪改查接口
 */
@Dao
interface TaskDao {
    @Query("SELECT * FROM tasks ORDER BY startTime")
    fun getAllTasks(): LiveData<List<Task>>
 
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun insert(task: Task)
 
    @Delete
    suspend fun delete(task: Task)
}
 
// ---------------- 文件: AppDatabase.kt ----------------
package com.example.gantt.data
 
import androidx.room.Database
import androidx.room.RoomDatabase
 
/**
 * AppDatabase：Room 數(shù)據(jù)庫
 */
@Database(entities = [Task::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun taskDao(): TaskDao
}
 
// ---------------- 文件: GanttViewModel.kt ----------------
package com.example.gantt.viewmodel
 
import android.app.Application
import androidx.lifecycle.*
import androidx.room.Room
import com.example.gantt.data.AppDatabase
import com.example.gantt.data.Task
import kotlinx.coroutines.launch
 
/**
 * GanttViewModel：持有任務(wù)列表，提供增刪改查
 */
class GanttViewModel(application: Application) : AndroidViewModel(application) {
    private val db = Room.databaseBuilder(application, AppDatabase::class.java, "gantt.db").build()
    private val dao = db.taskDao()
 
    val tasks: LiveData<List<Task>> = dao.getAllTasks()
 
    fun addTask(task: Task) = viewModelScope.launch {
        dao.insert(task)
    }
 
    fun deleteTask(task: Task) = viewModelScope.launch {
        dao.delete(task)
    }
}
 
// ---------------- 文件: activity_main.xml ----------------
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent" android:layout_height="match_parent">
 
    <!-- 左側(cè)任務(wù)名稱列表 -->
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rvTasks"
        android:layout_width="120dp" android:layout_height="0dp"
        app:layout_constraintTop_toTopOf="parent" app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"/>
 
    <!-- 右側(cè)甘特圖區(qū)域，水平滾動 -->
    <HorizontalScrollView
        android:id="@+id/scrollHorizontal"
        android:layout_width="0dp" android:layout_height="0dp"
        android:scrollbars="none"
        app:layout_constraintTop_toTopOf="parent" app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@id/rvTasks" app:layout_constraintEnd_toEndOf="parent">
 
        <com.example.gantt.ui.GanttChartView
            android:id="@+id/ganttView"
            android:layout_width="wrap_content" android:layout_height="match_parent"/>
 
    </HorizontalScrollView>
 
    <!-- 新增任務(wù)按鈕 -->
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fabAdd"
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        app:srcCompat="@android:drawable/ic_input_add"
        app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent"
        android:layout_margin="16dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>
 
// ---------------- 文件: item_task_name.xml ----------------
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tvTaskName"
    android:layout_width="match_parent" android:layout_height="48dp"
    android:gravity="center_vertical"
    android:paddingStart="8dp"
    android:textSize="16sp"
    android:textColor="#333"/>
 
// ---------------- 文件: TaskNameAdapter.kt ----------------
package com.example.gantt.ui
 
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.ListAdapter
import androidx.recyclerview.widget.RecyclerView
import com.example.gantt.data.Task
import com.example.gantt.databinding.ItemTaskNameBinding
 
/**
 * TaskNameAdapter：左側(cè)任務(wù)名稱列表
 */
class TaskNameAdapter : ListAdapter<Task, TaskNameAdapter.NameVH>(DIFF) {
    companion object {
        val DIFF = object : DiffUtil.ItemCallback<Task>() {
            override fun areItemsTheSame(old: Task, new: Task) = old.id == new.id
            override fun areContentsTheSame(old: Task, new: Task) = old == new
        }
    }
    inner class NameVH(val binding: ItemTaskNameBinding) : RecyclerView.ViewHolder(binding.root)
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
        NameVH(ItemTaskNameBinding.inflate(LayoutInflater.from(parent.context), parent, false))
    override fun onBindViewHolder(holder: NameVH, position: Int) {
        holder.binding.tvTaskName.text = getItem(position).name
    }
}
 
// ---------------- 文件: GanttChartView.kt ----------------
package com.example.gantt.ui
 
import android.content.Context
import android.graphics.*
import android.util.AttributeSet
import android.view.*
import android.widget.OverScroller
import androidx.core.content.ContextCompat
import com.example.gantt.R
import com.example.gantt.data.Task
import org.threeten.bp.Instant
import org.threeten.bp.ZoneId
 
/**
 * GanttChartView：自定義甘特圖 View
 */
class GanttChartView @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null
): View(context, attrs), GestureDetector.OnGestureListener, ScaleGestureDetector.OnScaleGestureListener {
 
    // 數(shù)據(jù)
    private var tasks: List<Task> = emptyList()
    private var minTime = Long.MAX_VALUE
    private var maxTime = 0L
    private var timeSpan = 1L // ms
 
    // 畫筆
    private val barPaint = Paint(Paint.ANTI_ALIAS_FLAG)
    private val axisPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply { color = Color.GRAY; strokeWidth=2f }
    private val textPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply { color = Color.DKGRAY; textSize = 24f }
 
    // 布局參數(shù)
    private val rowHeight = 80f
    private val headerHeight = 80f
    private var scaleFactor = 1f
    private var offsetX = 0f
 
    // 手勢
    private val scroller = OverScroller(context)
    private val gestureDetector = GestureDetector(context, this)
    private val scaleDetector = ScaleGestureDetector(context, this)
 
    init {
        barPaint.style = Paint.Style.FILL
    }
 
    /** 外部設(shè)置任務(wù)并重新計算范圍 */
    fun setTasks(list: List<Task>) {
        tasks = list
        if (tasks.isNotEmpty()) {
            minTime = tasks.minOf { it.startTime }
            maxTime = tasks.maxOf { it.endTime }
            timeSpan = maxTime - minTime
        }
        invalidate()
    }
 
    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        if (tasks.isEmpty()) return
 
        // 1. 繪制時間軸
        val totalWidth = width.toFloat() * scaleFactor
        val tickCount = 6
        for (i in 0..tickCount) {
            val x = offsetX + i / tickCount.toFloat() * totalWidth
            canvas.drawLine(x, 0f, x, headerHeight, axisPaint)
            val time = minTime + i / tickCount.toFloat() * timeSpan
            val label = Instant.ofEpochMilli(time)
                .atZone(ZoneId.systemDefault()).toLocalDate().toString()
            canvas.drawText(label, x + 10, headerHeight - 20, textPaint)
        }
 
        // 2. 繪制每行任務(wù)條
        tasks.forEachIndexed { idx, task ->
            val top = headerHeight + idx * rowHeight
            val bottom = top + rowHeight * 0.6f
            // 計算左右
            val left = offsetX + (task.startTime - minTime) / timeSpan.toFloat() * totalWidth
            val right = offsetX + (task.endTime - minTime) / timeSpan.toFloat() * totalWidth
            barPaint.color = task.color
            canvas.drawRect(left, top + 10, right, bottom, barPaint)
        }
    }
 
    // ================ 手勢與縮放 ================
    override fun onTouchEvent(event: MotionEvent): Boolean {
        scaleDetector.onTouchEvent(event)
        if (!scaleDetector.isInProgress) {
            gestureDetector.onTouchEvent(event)
        }
        return true
    }
    override fun onScale(detector: ScaleGestureDetector): Boolean {
        scaleFactor *= detector.scaleFactor
        scaleFactor = scaleFactor.coerceIn(0.5f, 3f)
        invalidate()
        return true
    }
    override fun onScaleBegin(detector: ScaleGestureDetector) = true
    override fun onScaleEnd(detector: ScaleGestureDetector) {}
    override fun onDown(e: MotionEvent) = true
    override fun onShowPress(e: MotionEvent) {}
    override fun onSingleTapUp(e: MotionEvent) = false
    override fun onScroll(e1: MotionEvent, e2: MotionEvent, dx: Float, dy: Float): Boolean {
        offsetX -= dx
        offsetX = offsetX.coerceIn(-width.toFloat(), width.toFloat() * scaleFactor)
        invalidate()
        return true
    }
    override fun onLongPress(e: MotionEvent) {}
    override fun onFling(e1: MotionEvent, e2: MotionEvent, vx: Float, vy: Float): Boolean {
        scroller.fling(
            offsetX.toInt(), 0,
            vx.toInt(), 0,
            (-width).toInt(), (width * scaleFactor).toInt(),
            0, 0
        )
        postInvalidateOnAnimation()
        return true
    }
    override fun computeScroll() {
        if (scroller.computeScrollOffset()) {
            offsetX = scroller.currX.toFloat()
            invalidate()
        }
    }
}
 
// ---------------- 文件: MainActivity.kt ----------------
package com.example.gantt.ui
 
import android.os.Bundle
import androidx.activity.viewModels
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.gantt.databinding.ActivityMainBinding
import com.example.gantt.data.Task
import com.example.gantt.viewmodel.GanttViewModel
import org.threeten.bp.ZonedDateTime
 
/**
 * MainActivity：示例甘特圖展示
 */
class MainActivity : AppCompatActivity() {
    private lateinit var binding: ActivityMainBinding
    private val vm: GanttViewModel by viewModels()
 
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
 
        // 左側(cè)任務(wù)名列表
        val nameAdapter = TaskNameAdapter()
        binding.rvTasks.apply {
            layoutManager = LinearLayoutManager(this@MainActivity)
            adapter = nameAdapter
        }
 
        // 觀察任務(wù)數(shù)據(jù)
        vm.tasks.observe(this) { list ->
            nameAdapter.submitList(list)
            binding.ganttView.setTasks(list)
        }
 
        // 新增示例任務(wù)
        binding.fabAdd.setOnClickListener {
            val now = System.currentTimeMillis()
            val task = Task(
                name = "任務(wù)${now%100}",
                startTime = now,
                endTime = now + 3600_000 * (1 + (now%5).toInt()),
                color = android.graphics.Color.rgb(((now/1000)%255).toInt(),120,150)
            )
            vm.addTask(task)
        }
    }
}
 
// ---------------- 文件: activity_main.xml (ViewBinding) ----------------
<?xml version="1.0" encoding="utf-8"?>
<layout  xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:app="http://schemas.android.com/apk/res-auto">
  <data/>
  <androidx.constraintlayout.widget.ConstraintLayout
      android:layout_width="match_parent" android:layout_height="match_parent">
 
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rvTasks"
        android:layout_width="120dp" android:layout_height="0dp"
        app:layout_constraintTop_toTopOf="parent" app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"/>
 
    <HorizontalScrollView
        android:id="@+id/scrollHorizontal"
        android:layout_width="0dp" android:layout_height="0dp"
        android:scrollbars="none"
        app:layout_constraintTop_toTopOf="parent" app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@id/rvTasks" app:layout_constraintEnd_toEndOf="parent">
 
      <com.example.gantt.ui.GanttChartView
          android:id="@+id/ganttView"
          android:layout_width="2000dp" android:layout_height="match_parent"/>
    </HorizontalScrollView>
 
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fabAdd"
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        app:srcCompat="@android:drawable/ic_input_add"
        app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent"
        android:layout_margin="16dp"/>
  </androidx.constraintlayout.widget.ConstraintLayout>
</layout>