feature: Show a tooltip for the chart

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/Chart.kt

@@ -18,6 +18,7 @@ import java.awt.RenderingHints
 import java.awt.geom.Rectangle2D
 import java.beans.PropertyChangeListener
 import java.beans.PropertyChangeSupport
+import javax.swing.*
 
 /**
  * A chart that can be inlaid into a small space.
@@ -73,7 +74,7 @@ class Chart : RectangleContent {
 
     /**
      * The insets for the plot area (defaults to zero but can be modified to add space for
-     * annotations etc).
+     * annotations, etc.).
      */
     var plotInsets = RectangleMargin(0.0, 0.0, 0.0, 0.0)
         set(value) {
@@ -86,6 +87,26 @@ class Chart : RectangleContent {
             propertyChangeSupport.firePropertyChange("plotInsets", oldPlotInsets, value)
         }
 
+    fun createToolTipComponent(bounds: Rectangle2D, mousePosition: Point?): JComponent? {
+        val plotArea = plotInsets.shrink(bounds)
+        val constituents = chartSpecifications.mapNotNull {
+            val toolTipComponentContributor = configureRenderer(it.renderer) as? ToolTipComponentContributor
+            toolTipComponentContributor?.createToolTipComponent(it, plotArea, mousePosition)
+        }
+        constituents.ifEmpty { return null }
+
+        return JPanel().apply {
+            layout = BoxLayout(this, BoxLayout.Y_AXIS)
+
+            constituents.forEachIndexed { index, it ->
+                add(it)
+                if (index < constituents.size - 1) {
+                    add(JSeparator())
+                }
+            }
+        }
+    }
+
     /**
      * Creates a new chart with the given specifications, dataset and renderer.
      *
@@ -139,6 +160,7 @@ class Chart : RectangleContent {
             is LineRendererDescriptor -> lineChartRenderer.apply {
                 linePaint = rendererSpec.lineColor ?: Color.BLACK
                 fillColors = rendererSpec.fillColors
+                tooltipFunction = rendererSpec.tooltipFunction
             }
 
             else -> error("Unsupported render spec")

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/ChartComponent.kt

@@ -35,6 +35,9 @@ class ChartComponent(chart: Chart? = null) : JComponent() {
             propertyChangeSupport.firePropertyChange("chart", oldChart, value)
         }
 
+    val toolTipComponent: JComponent?
+        get() = chart?.createToolTipComponent(getBounds(rect), mousePosition)
+
     /** A reusable rectangle to avoid creating work for the garbage collector.  */
     private val rect = Rectangle()
 

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/ChartDataset.kt

@@ -9,11 +9,14 @@
  */
 package io.github.bric3.fireplace.charts
 
+import io.github.bric3.fireplace.charts.XYDataset.XY
+
 interface ChartDataset {
     val label: String
     val rangeOfX: Range<Long>
     val rangeOfY: Range<Double>
     val itemCount: Int
     fun xAt(index: Int): Long
     fun yAt(index: Int): Double?
+    fun xyAt(index: Int): XY<Long, Double>
 }

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/ChartSpecification.kt

@@ -9,7 +9,9 @@
  */
 package io.github.bric3.fireplace.charts
 
+import io.github.bric3.fireplace.charts.XYDataset.XY
 import java.awt.Color
+import javax.swing.*
 
 /**
  * Specifies the various properties of a chart (dataset, label, how it's rendered).
@@ -30,5 +32,6 @@ data class ChartSpecification(
     data class LineRendererDescriptor(
         val lineColor: Color? = null,
         val fillColors: List<Color>? = null,
+        val tooltipFunction: (XY<Long, Double>, String) -> JComponent? = { _, _ -> null },
     ) : RendererDescriptor
 }

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/ChartUtils.kt

@@ -10,6 +10,9 @@
 package io.github.bric3.fireplace.charts
 
 import java.awt.Color
+import java.time.Instant
+import java.time.ZoneId
+import java.time.format.DateTimeFormatter
 import java.util.concurrent.TimeUnit.MILLISECONDS
 
 
@@ -20,13 +23,32 @@ fun Color.withAlpha(alpha: Float) = Color(
     (alpha * 255).toInt()
 )
 
+fun Color.withAlpha(alpha: Int): Color {
+    require(alpha in 0..255) { "Alpha value must be between 0 and 255" }
+    return Color(
+        red,
+        green,
+        blue,
+        alpha
+    )
+}
+
 fun presentableDuration(durationMs: Long): String {
     val millis = durationMs % 1000L
     val seconds = MILLISECONDS.toSeconds(durationMs) % 60L
     val minutes = MILLISECONDS.toMinutes(durationMs) % 60L
     val hours = MILLISECONDS.toHours(durationMs)
     return String.format(
         "%02d:%02d:%02d.%03d",
-        arrayOf(hours, minutes, seconds, millis)
+        hours, minutes, seconds, millis
     )
+}
+
+private val timestampFormatter = DateTimeFormatter.ofPattern("LLL d, H:mm:ss")
+fun presentableTime(epochMs: Long): String {
+    return timestampFormatter.format(Instant.ofEpochMilli(epochMs).atZone(ZoneId.systemDefault()))
+}
+
+fun presentablePercentage(value: Double): String {
+    return String.format("%.2f%%", value * 100)
 }

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/LineChartRenderer.kt

@@ -9,6 +9,7 @@
  */
 package io.github.bric3.fireplace.charts
 
+import io.github.bric3.fireplace.charts.XYDataset.XY
 import io.github.bric3.fireplace.core.ui.Colors
 import io.github.bric3.fireplace.core.ui.LightDarkColor
 import io.github.bric3.fireplace.ui.toolkit.UIUtil
@@ -22,6 +23,7 @@ import java.awt.Stroke
 import java.awt.geom.Ellipse2D
 import java.awt.geom.Path2D
 import java.awt.geom.Rectangle2D
+import javax.swing.*
 import kotlin.math.abs
 
 
@@ -38,7 +40,7 @@ class LineChartRenderer(
         BasicStroke.JOIN_ROUND
     ),
     paint: Paint = LightDarkColor(Color.BLACK, Color.WHITE),
-) : ChartRenderer {
+) : ChartRenderer, ToolTipComponentContributor {
 
     /**
      * The gradient fill colors, either `null`, one color, or at most two colors.
@@ -58,6 +60,11 @@ class LineChartRenderer(
      */
     var linePaint = paint
 
+    /**
+     * The tooltip function that will be called to create a tooltip component for a given XY value.
+     */
+    var tooltipFunction: (XY<Long, Double>, String) -> JComponent? = { _, _ -> null }
+
     /**
      * A shape that will be drawn at the point of the last value in the series.
      * Leave as null if you don't want anything drawn.
@@ -227,6 +234,40 @@ class LineChartRenderer(
         }
     }
 
+    override fun createToolTipComponent(
+        chart: ChartSpecification,
+        plotBounds: Rectangle2D,
+        mousePosition: Point?
+    ): JComponent? {
+        val dataset = chart.dataset
+        val itemCount = dataset.itemCount
+        if (itemCount == 0) return null
+        val xRange = dataset.rangeOfX
+        var yRange = dataset.rangeOfY
+        if (includeZeroInYRange) {
+            yRange = yRange.include(0.0)
+        }
+
+        val hasContributor = mousePosition != null && mousePosition.x >= plotBounds.x && mousePosition.x <= plotBounds.maxX
+        if (!hasContributor) return null
+
+        var closestXY: XY<Long, Double>? = null
+        var closestItemX = Double.MAX_VALUE
+        for (i in 0 until itemCount) {
+            if (yRange.isZeroLength) continue
+            val xy = dataset.xyAt(i)
+            val xx = plotBounds.x + xRange.ratioFor(xy.x) * plotBounds.width
+            // discover the closest item to the mouse adjusted position
+            val distance = abs(xx - mousePosition!!.x)
+            if (distance < closestItemX) {
+                closestItemX = distance
+                closestXY = xy
+            }
+        }
+
+        return closestXY?.let { tooltipFunction(it, chart.label) }
+    }
+
     companion object {
         /**
          * Creates a new [GradientPaint] instance based on the supplied colors and with coordinates

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/ToolTipComponentContributor.kt

@@ -0,0 +1,18 @@
+/*
+ * Fireplace
+ *
+ * Copyright (c) 2021, Today - Brice Dutheil
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+package io.github.bric3.fireplace.charts
+
+import java.awt.Point
+import java.awt.geom.Rectangle2D
+import javax.swing.*
+
+interface ToolTipComponentContributor {
+    fun createToolTipComponent(chart: ChartSpecification, plotArea: Rectangle2D, mousePosition: Point?): JComponent?
+}

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/charts/XYDataset.kt

@@ -58,6 +58,10 @@ open class XYDataset(
     override val itemCount: Int
         get() = items.size
 
+    override fun xyAt(index: Int): XY<Long, Double> {
+        return items[index]
+    }
+
     override fun xAt(index: Int): Long {
         return items[index].x
     }

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/jfr/views/cpu/MethodCpuSample.kt

@@ -15,13 +15,17 @@ import io.github.bric3.fireplace.charts.ChartSpecification
 import io.github.bric3.fireplace.charts.ChartSpecification.LineRendererDescriptor
 import io.github.bric3.fireplace.charts.XYDataset.XY
 import io.github.bric3.fireplace.charts.XYPercentageDataset
+import io.github.bric3.fireplace.charts.presentablePercentage
+import io.github.bric3.fireplace.charts.presentableTime
 import io.github.bric3.fireplace.charts.withAlpha
 import io.github.bric3.fireplace.jfr.support.JFRLoaderBinder
 import io.github.bric3.fireplace.jfr.support.JfrAnalyzer
 import io.github.bric3.fireplace.jfr.support.getMemberFromEvent
 import io.github.bric3.fireplace.ui.CPU_BASE
 import io.github.bric3.fireplace.ui.ThreadFlamegraphView
 import io.github.bric3.fireplace.ui.ViewPanel.Priority
+import io.github.bric3.fireplace.ui.toolkit.ColorIcon
+import io.github.bric3.fireplace.ui.toolkit.FollowingTipService
 import org.openjdk.jmc.common.IDisplayable
 import org.openjdk.jmc.common.unit.UnitLookup
 import org.openjdk.jmc.flightrecorder.JfrAttributes
@@ -41,6 +45,10 @@ class MethodCpuSample(jfrBinder: JFRLoaderBinder) : ThreadFlamegraphView(jfrBind
                 minimumSize = Dimension(99999, 84)
                 size = size.apply { height = 84 }
                 preferredSize = Dimension(99999, 84)
+
+                FollowingTipService.enableFor(this) { chart, _ ->
+                    chart.toolTipComponent
+                }
             }
 
             jfrBinder.bindEvents(
@@ -93,6 +101,12 @@ class MethodCpuSample(jfrBinder: JFRLoaderBinder) : ThreadFlamegraphView(jfrBind
 
                     Chart(
                         buildList {
+                            fun tooltipFunction(color: Color): (XY<Long, Double>, String) -> JComponent = { xy, label ->
+                                JLabel("<html>$label: <strong>${presentablePercentage(xy.y)}</strong> at <strong>${presentableTime(xy.x)}</strong></html>").apply {
+                                    icon = ColorIcon(14, color)
+                                }
+                            }
+
                             if (cpuUserLoadValues.isNotEmpty()) {
                                 add(
                                     ChartSpecification(
@@ -101,6 +115,7 @@ class MethodCpuSample(jfrBinder: JFRLoaderBinder) : ThreadFlamegraphView(jfrBind
                                         LineRendererDescriptor(
                                             lineColor = Color.GREEN,
                                             fillColors = listOf(Color.GREEN.withAlpha(0.4f), Color.GREEN.withAlpha(0.01f)),
+                                            tooltipFunction = tooltipFunction(Color.GREEN)
                                         )
                                     )
                                 )
@@ -113,6 +128,7 @@ class MethodCpuSample(jfrBinder: JFRLoaderBinder) : ThreadFlamegraphView(jfrBind
                                         LineRendererDescriptor(
                                             lineColor = Color.RED,
                                             fillColors = listOf(Color.RED.withAlpha(0.4f), Color.RED.withAlpha(0.01f)),
+                                            tooltipFunction = tooltipFunction(Color.RED)
                                         )
                                     )
                                 )

fireplace-app/src/main/kotlin/io/github/bric3/fireplace/ui/toolkit/ColorIcon.kt

@@ -0,0 +1,70 @@
+/*
+ * Fireplace
+ *
+ * Copyright (c) 2021, Today - Brice Dutheil
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+package io.github.bric3.fireplace.ui.toolkit
+
+import io.github.bric3.fireplace.charts.withAlpha
+import java.awt.Color
+import java.awt.Component
+import java.awt.Graphics
+import java.awt.Graphics2D
+import java.awt.RenderingHints
+import javax.swing.*
+
+open class ColorIcon(
+    private val width: Int,
+    private val height: Int,
+    private val colorWidth: Int,
+    private val colorHeight: Int,
+    private val color: Color,
+    private val isPaintBorder: Boolean,
+    private val arc: Int = 6
+) : Icon {
+    constructor(size: Int, colorSize: Int, color: Color, border: Boolean) : this(
+        size,
+        size,
+        colorSize,
+        colorSize,
+        color,
+        border,
+        6
+    )
+
+    constructor(size: Int, color: Color, border: Boolean = false) : this(size, size, color, border)
+
+    override fun paintIcon(component: Component, g: Graphics, i: Int, j: Int) {
+        val g2d = g.create() as Graphics2D
+        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON)
+        g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_NORMALIZE)
+        g2d.color = color
+
+        val width = colorWidth
+        val height = colorHeight
+        val arc = arc
+        val x = i + (this.width - width) / 2
+        val y = j + (this.height - height) / 2
+
+        g2d.fillRoundRect(x, y, width, height, arc, arc)
+
+        if (isPaintBorder) {
+            g2d.color = Color(0, true).withAlpha(40) // TODO put in Colors
+            g2d.drawRoundRect(x, y, width, height, arc, arc)
+        }
+
+        g2d.dispose()
+    }
+
+    override fun getIconWidth(): Int {
+        return width
+    }
+
+    override fun getIconHeight(): Int {
+        return height
+    }
+}