From 17be9007e0572102676a7f21e0cbd9259e5aa94a Mon Sep 17 00:00:00 2001
From: Tianyue Cheng <90072894+tianyue-berkeley@users.noreply.github.com>
Date: Thu, 25 Nov 2021 14:29:09 -0800
Subject: [PATCH 1/2] Horizontal Gridlines

---
 src/main/scala/BTreeChart.scala |  1 +
 src/main/scala/GridCanvas.scala | 17 ++++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/main/scala/BTreeChart.scala b/src/main/scala/BTreeChart.scala
index 881bde3..e86e045 100644
--- a/src/main/scala/BTreeChart.scala
+++ b/src/main/scala/BTreeChart.scala
@@ -87,6 +87,7 @@ case class ChartParameters(width: Int, height: Int, xMin: Long, xMax: Long, yMin
   def xValToPos(value: Long): Double = (value - xMin) * xScale
   def xPosToVal(pos: Double): Long = (pos / xScale).toLong + xMin
   def yValToPos(value: Double): Double = (yMax - value) * yScale
+  def yPosToVal(pos: Double): Double = yMax - (pos / yScale)
 
   // TODO is this the right place for these functions to live?
   def timestampFromDateTime(dateTime: ZonedDateTime): Long = {
diff --git a/src/main/scala/GridCanvas.scala b/src/main/scala/GridCanvas.scala
index 4cb5359..9cf7753 100644
--- a/src/main/scala/GridCanvas.scala
+++ b/src/main/scala/GridCanvas.scala
@@ -38,6 +38,21 @@ class GridCanvas extends ResizableCanvas {
     gc.restore()
   }
 
+
+  protected def drawValueLines(gc: GraphicsContext, scale: ChartParameters): Unit = {
+    gc.save()
+    gc.setStroke(gc.getStroke.asInstanceOf[Color].deriveColor(0, 1, 1, GRIDLINE_ALPHA))
+    gc.setLineWidth(CONTEXT_GRIDLINE_WIDTH)
+    val v_interval = List.range(0,scale.height,64)
+    v_interval.foreach{ value =>
+      gc.strokeLine(0,value,scale.width,value)
+//      println(s"DEBUG: value: $value")
+      RenderHelper.drawContrastText(gc, ChartCommon.CONTRAST_BACKGROUND, scale.yPosToVal(value).toString,
+        20, value)
+    }
+    gc.restore()
+  }
+
   protected def drawRulers(gc: GraphicsContext, scale: ChartParameters,
                            priorContextTime: ZonedDateTime,
                            tickTimes: Seq[ZonedDateTime], contextTimes: Seq[ZonedDateTime]): Unit = {
@@ -86,6 +101,6 @@ class GridCanvas extends ResizableCanvas {
 
     drawGridlines(gc, scale, tickTimes, contextTimes)
     drawRulers(gc, scale, priorContextTime, tickTimes, contextTimes)
-
+    drawValueLines(gc,scale)
   }
 }

From 317c91df458f8ac644f00333fce048fe5d98852d Mon Sep 17 00:00:00 2001
From: Tianyue Cheng <90072894+tianyue-berkeley@users.noreply.github.com>
Date: Thu, 25 Nov 2021 14:44:53 -0800
Subject: [PATCH 2/2] Rounding up

---
 src/main/scala/GridCanvas.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/scala/GridCanvas.scala b/src/main/scala/GridCanvas.scala
index 9cf7753..9ac744a 100644
--- a/src/main/scala/GridCanvas.scala
+++ b/src/main/scala/GridCanvas.scala
@@ -47,7 +47,7 @@ class GridCanvas extends ResizableCanvas {
     v_interval.foreach{ value =>
       gc.strokeLine(0,value,scale.width,value)
 //      println(s"DEBUG: value: $value")
-      RenderHelper.drawContrastText(gc, ChartCommon.CONTRAST_BACKGROUND, scale.yPosToVal(value).toString,
+      RenderHelper.drawContrastText(gc, ChartCommon.CONTRAST_BACKGROUND, ((scale.yPosToVal(value) * 100).round / 100.toDouble).toString,
         20, value)
     }
     gc.restore()