Implemented GraphUtil.createPath

app/src/main/java/com/geeksville/mesh/ui/components/DeviceMetrics.kt

@@ -66,7 +66,7 @@ import com.geeksville.mesh.ui.components.CommonCharts.MS_PER_SEC
 import com.geeksville.mesh.ui.components.CommonCharts.DATE_TIME_FORMAT
 import com.geeksville.mesh.ui.theme.Orange
 import com.geeksville.mesh.util.GraphUtil.plotPoint
-import java.util.concurrent.TimeUnit
+import com.geeksville.mesh.util.GraphUtil.createPath
 
 private val DEVICE_METRICS_COLORS = listOf(Color.Green, Color.Magenta, Color.Cyan)
 private const val MAX_PERCENT_VALUE = 100f
@@ -224,45 +224,25 @@ private fun DeviceMetricsChart(
                     )
                 }
 
-                // TODO this works to draw lines only according to it's time
-                //  Can this be made into a function that could be reused for other graphs???
+                /* Battery Line */
                 var index = 0
-                var timeBreak = false
                 while (index < telemetries.size) {
-                    val testPath = Path().apply {
-                        while(index < telemetries.size) {
-                            val telemetry = telemetries[index]
-                            val nextTelemetry = telemetries.getOrNull(index + 1) ?: telemetries.last()
-
-                            /* Check to see if we have a significant time break between telemetries. */
-                            if (nextTelemetry.time - telemetry.time > TimeUnit.HOURS.toSeconds(2)) { // TODO constant
-                                timeBreak = true
-                                index++
-                                break
-                            }
-
-                            val x1Ratio = (telemetry.time - oldest.time).toFloat() / timeDiff
-                            val x1 = x1Ratio * width
-                            val y1Ratio = telemetry.deviceMetrics.batteryLevel / MAX_PERCENT_VALUE
-                            val y1 = height - (y1Ratio * height)
-
-                            val x2Ratio = (nextTelemetry.time - oldest.time).toFloat() / timeDiff
-                            val x2 = x2Ratio * width
-                            val y2Ratio = nextTelemetry.deviceMetrics.batteryLevel / MAX_PERCENT_VALUE
-                            val y2 = height - (y2Ratio * height)
-
-                            if (timeBreak || index == 0) {
-                                timeBreak = false
-                                moveTo(x1, y1)
-                            }
-
-                            quadraticTo(x1, y1, (x1 + x2) / 2f, (y1 + y2) / 2f)
-
-                            index++
-                        }
+                    val path = Path()
+                    index = createPath(
+                        telemetries = telemetries,
+                        index = index,
+                        path = path,
+                        oldestTime = oldest.time,
+                        timeRange = timeDiff,
+                        width = width
+                    ) { i ->
+                        val telemetry = telemetries.getOrNull(i) ?: telemetries.last()
+                        val ratio = telemetry.deviceMetrics.batteryLevel / MAX_PERCENT_VALUE
+                        val y = height - (ratio * height)
+                        return@createPath y
                     }
                     drawPath(
-                        path = testPath,
+                        path = path,
                         color = DEVICE_METRICS_COLORS[Device.BATTERY.ordinal],
                         style = Stroke(
                             width = dataPointRadius,

app/src/main/java/com/geeksville/mesh/util/GraphUtil.kt

@@ -1,8 +1,13 @@
 package com.geeksville.mesh.util
 
+import androidx.compose.ui.graphics.Path
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.drawscope.DrawContext
+import com.geeksville.mesh.TelemetryProtos.Telemetry
+import java.util.concurrent.TimeUnit
+
+private const val TIME_SEPARATION_THRESHOLD = 2L
 
 object GraphUtil {
 
@@ -28,5 +33,56 @@ object GraphUtil {
         )
     }
 
-    // TODO implement drawing line
+    /**
+     * Creates a [Path] that could be used to draw a line from the `index` to the end of `telemetries`
+     * or the last point before a time separation between [Telemetry]s.
+     *
+     * @param telemetries data used to create the [Path]
+     * @param index current place in the [List]
+     * @param path [Path] that will be used to draw
+     * @param timeRange The time range for the data set
+     * @param width of the [DrawContext]
+     * @param calculateY (`index`) -> `y` coordinate
+     */
+    fun createPath(
+        telemetries: List<Telemetry>,
+        index: Int,
+        path: Path,
+        oldestTime: Int,
+        timeRange: Int,
+        width: Float,
+        calculateY: (Int) -> Float
+    ): Int {
+        var i = index
+        var isNewLine = true
+        with (path) {
+            while (i < telemetries.size) {
+                val telemetry = telemetries[i]
+                val nextTelemetry = telemetries.getOrNull(i + 1) ?: telemetries.last()
+
+                /* Check to see if we have a significant time break between telemetries. */
+                if (nextTelemetry.time - telemetry.time > TimeUnit.HOURS.toSeconds(TIME_SEPARATION_THRESHOLD)) {
+                    i++
+                    break
+                }
+
+                val x1Ratio = (telemetry.time - oldestTime).toFloat() / timeRange
+                val x1 = x1Ratio * width
+                val y1 = calculateY(i)
+
+                val x2Ratio = (nextTelemetry.time - oldestTime).toFloat() / timeRange
+                val x2 = x2Ratio * width
+                val y2 = calculateY(i + 1)
+
+                if (isNewLine || i == 0) {
+                    isNewLine = false
+                    moveTo(x1, y1)
+                }
+
+                quadraticTo(x1, y1, (x1 + x2) / 2f, (y1 + y2) / 2f)
+                i++
+            }
+        }
+        return i
+    }
 }