Grantt chart

Inspired by PhilJay/MPAndroidChart#5519

Author: hannesa2

app/src/main/AndroidManifest.xml

@@ -60,6 +60,7 @@
         <activity android:name="info.appdev.chartexample.HalfPieChartActivity" />
         <activity android:name="info.appdev.chartexample.SpecificPositionsLineChartActivity" />
         <activity android:name="info.appdev.chartexample.TimeLineActivity" />
+        <activity android:name="info.appdev.chartexample.TimeIntervalBarChartActivity" />
     </application>
 
 </manifest>

app/src/main/kotlin/info/appdev/chartexample/GanttUtils.kt

@@ -0,0 +1,50 @@
+package info.appdev.chartexample
+
+import info.appdev.charting.data.BarEntry
+
+/**
+ * Utility class for creating time interval entries for Gantt-style charts.
+ * Provides helper methods to create BarEntry objects with time interval data.
+ */
+object GanttUtils {
+    /**
+     * Create a time interval entry for a single task.
+     *
+     * @param taskIndex Y-axis position (task row)
+     * @param startTime Start time value
+     * @param duration Duration value
+     * @return BarEntry configured for time interval rendering
+     */
+    fun createTimeIntervalEntry(taskIndex: Float, startTime: Float, duration: Float): BarEntry {
+        return BarEntry(taskIndex, floatArrayOf(startTime, duration))
+    }
+
+    /**
+     * Create a time interval entry with multiple segments.
+     * Useful for showing multiple time ranges for a single task.
+     *
+     * @param taskIndex Y-axis position (task row)
+     * @param timeIntervals Array of [start1, duration1, start2, duration2, ...]
+     * @return BarEntry configured for time interval rendering
+     */
+    fun createMultiSegmentEntry(taskIndex: Float, timeIntervals: FloatArray): BarEntry {
+        require(timeIntervals.size >= 2) { "timeIntervals must have at least 2 elements" }
+        return BarEntry(taskIndex, timeIntervals)
+    }
+
+    /**
+     * Create a time interval entry with custom data.
+     *
+     * @param taskIndex Y-axis position (task row)
+     * @param startTime Start time value
+     * @param duration Duration value
+     * @param data Custom data object
+     * @return BarEntry configured for time interval rendering with data
+     */
+    fun createTimeIntervalEntry(
+        taskIndex: Float, startTime: Float,
+        duration: Float, data: Any?
+    ): BarEntry {
+        return BarEntry(taskIndex, floatArrayOf(startTime, duration), data)
+    }
+}

app/src/main/kotlin/info/appdev/chartexample/TimeIntervalBarChartActivity.kt

@@ -0,0 +1,83 @@
+package info.appdev.chartexample
+
+import android.graphics.Color
+import android.os.Bundle
+import android.widget.SeekBar
+import android.widget.SeekBar.OnSeekBarChangeListener
+import info.appdev.chartexample.databinding.ActivityHorizontalbarchartBinding
+import info.appdev.chartexample.notimportant.DemoBase
+import info.appdev.charting.components.YAxis
+import info.appdev.charting.data.BarData
+import info.appdev.charting.data.BarDataSet
+import info.appdev.charting.data.BarEntry
+import info.appdev.charting.data.Entry
+import info.appdev.charting.highlight.Highlight
+import info.appdev.charting.listener.OnChartValueSelectedListener
+import info.appdev.chartexample.GanttUtils
+import timber.log.Timber
+
+/**
+ * using HorizontalBarChart for Gantt-style time interval visualization.
+ * Shows how to display tasks as horizontal bars with start time and duration.
+ */
+class TimeIntervalBarChartActivity : DemoBase(), OnSeekBarChangeListener, OnChartValueSelectedListener {
+
+    private lateinit var binding: ActivityHorizontalbarchartBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityHorizontalbarchartBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        // Create sample tasks with time intervals
+        val entries: MutableList<BarEntry> = ArrayList()
+
+        entries.add(GanttUtils.createMultiSegmentEntry(-1f, floatArrayOf(-50f, -20f, 20f, 50f)))
+        // starts at 0, duration 100
+        entries.add(GanttUtils.createTimeIntervalEntry(0f, 0f, 100f))
+        // starts at 50, duration 150
+        entries.add(GanttUtils.createTimeIntervalEntry(1f, 50f, 150f))
+        // starts at 150, duration 100
+        entries.add(GanttUtils.createTimeIntervalEntry(2f, 150f, 100f))
+
+        Timber.d(entries.joinToString(separator = "\n"))
+
+        // Create dataset with time interval data
+        val dataSet = BarDataSet(entries, "Tasks")
+        dataSet.setColors(
+            Color.GREEN,
+            Color.BLUE,
+            Color.YELLOW
+        )
+        dataSet.barBorderWidth = 1f
+        dataSet.barBorderColor = Color.BLACK
+
+        // Create and set data
+        val barData = BarData(dataSet)
+        barData.barWidth = 0.8f
+        binding.chart1.data = barData
+
+        // Configure chart
+        binding.chart1.setFitBars(true)
+        binding.chart1.isDrawValueAboveBar = true
+        binding.chart1.xAxis.setDrawLabels(true)
+
+        val yl = binding.chart1.axisLeft
+        yl.setPosition(YAxis.YAxisLabelPosition.OUTSIDE_CHART)
+
+        // Refresh
+        binding.chart1.invalidate()
+    }
+
+    override fun saveToGallery() = Unit
+
+    override fun onProgressChanged(p0: SeekBar?, p1: Int, p2: Boolean) = Unit
+
+    override fun onStartTrackingTouch(p0: SeekBar?) = Unit
+
+    override fun onStopTrackingTouch(p0: SeekBar?) = Unit
+
+    override fun onValueSelected(entry: Entry, highlight: Highlight) = Unit
+
+    override fun onNothingSelected() = Unit
+}

app/src/main/kotlin/info/appdev/chartexample/notimportant/MainActivity.kt

@@ -75,6 +75,7 @@ import info.appdev.chartexample.ScrollViewActivity
 import info.appdev.chartexample.SpecificPositionsLineChartActivity
 import info.appdev.chartexample.StackedBarActivity
 import info.appdev.chartexample.StackedBarActivityNegative
+import info.appdev.chartexample.TimeIntervalBarChartActivity
 import info.appdev.chartexample.TimeLineActivity
 import info.appdev.chartexample.compose.HorizontalBarComposeActivity
 import info.appdev.chartexample.compose.HorizontalBarFullComposeActivity
@@ -219,6 +220,7 @@ class MainActivity : ComponentActivity() {
             add(ContentItem("Demonstrate and fix issues"))
             add(ContentItem("Gradient", "Show a gradient edge case", GradientActivity::class.java))
             add(ContentItem("Timeline", "Show a time line with Unix timestamp", TimeLineActivity::class.java))
+            add(ContentItem("Timeinterval", "Grantt chart", TimeIntervalBarChartActivity::class.java))
         }
     }
 }