feat: Scrollable Signal Chart (#1505)

* Removed repeated calculation.

* Centralized the radius used to plot points and draw lines within GraphUtil.kt.

* Updated the signal metrics chart to use the scroll features.

* SignalMetricsChart long method warning suppression.

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

@@ -65,6 +65,7 @@ import com.geeksville.mesh.ui.BatteryInfo
 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
 import com.geeksville.mesh.util.GraphUtil.plotPoint
 import com.geeksville.mesh.util.GraphUtil.createPath
 
@@ -155,12 +156,12 @@ private fun DeviceMetricsChart(
     Spacer(modifier = Modifier.height(16.dp))
 
     val graphColor = MaterialTheme.colors.onSurface
-    val scrollState = rememberScrollState()
 
+    val scrollState = rememberScrollState()
     val configuration = LocalConfiguration.current
     val screenWidth = configuration.screenWidthDp
     val dp by remember(key1 = selectedTime) {
-        mutableStateOf(selectedTime.dp(screenWidth, time = (newest.time - oldest.time).toLong()))
+        mutableStateOf(selectedTime.dp(screenWidth, time = timeDiff.toLong()))
     }
 
     Row {
@@ -195,7 +196,6 @@ private fun DeviceMetricsChart(
 
                 val height = size.height
                 val width = size.width
-                val dataPointRadius = 2.dp.toPx()
                 for (i in telemetries.indices) {
                     val telemetry = telemetries[i]
 
@@ -207,7 +207,6 @@ private fun DeviceMetricsChart(
                     plotPoint(
                         drawContext = drawContext,
                         color = DEVICE_METRICS_COLORS[Device.CH_UTIL.ordinal],
-                        radius = dataPointRadius,
                         x = x,
                         value = telemetry.deviceMetrics.channelUtilization,
                         divisor = MAX_PERCENT_VALUE
@@ -217,7 +216,6 @@ private fun DeviceMetricsChart(
                     plotPoint(
                         drawContext = drawContext,
                         color = DEVICE_METRICS_COLORS[Device.AIR_UTIL.ordinal],
-                        radius = dataPointRadius,
                         x = x,
                         value = telemetry.deviceMetrics.airUtilTx,
                         divisor = MAX_PERCENT_VALUE
@@ -246,7 +244,7 @@ private fun DeviceMetricsChart(
                         path = path,
                         color = DEVICE_METRICS_COLORS[Device.BATTERY.ordinal],
                         style = Stroke(
-                            width = dataPointRadius,
+                            width = GraphUtil.RADIUS,
                             cap = StrokeCap.Round
                         )
                     )

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

@@ -17,9 +17,8 @@
 
 package com.geeksville.mesh.ui.components
 
-import android.graphics.Paint
-import android.graphics.Typeface
 import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.horizontalScroll
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -31,8 +30,10 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.text.selection.SelectionContainer
 import androidx.compose.material.Card
 import androidx.compose.material.Surface
@@ -46,11 +47,8 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.nativeCanvas
-import androidx.compose.ui.graphics.toArgb
-import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
@@ -60,11 +58,10 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.geeksville.mesh.MeshProtos.MeshPacket
 import com.geeksville.mesh.R
 import com.geeksville.mesh.model.MetricsViewModel
+import com.geeksville.mesh.model.TimeFrame
 import com.geeksville.mesh.ui.components.CommonCharts.MS_PER_SEC
-import com.geeksville.mesh.ui.components.CommonCharts.LINE_LIMIT
-import com.geeksville.mesh.ui.components.CommonCharts.TEXT_PAINT_ALPHA
-import com.geeksville.mesh.ui.components.CommonCharts.LEFT_LABEL_SPACING
 import com.geeksville.mesh.ui.components.CommonCharts.DATE_TIME_FORMAT
+import com.geeksville.mesh.util.GraphUtil.plotPoint
 
 private val METRICS_COLORS = listOf(Color.Green, Color.Blue)
 
@@ -108,6 +105,7 @@ fun SignalMetricsScreen(
                 .fillMaxWidth()
                 .fillMaxHeight(fraction = 0.33f),
             meshPackets = data.reversed(),
+            selectedTimeFrame,
             promptInfoDialog = { displayInfoDialog = true }
         )
 
@@ -126,21 +124,30 @@ fun SignalMetricsScreen(
     }
 }
 
+@Suppress("LongMethod")
 @Composable
 private fun SignalMetricsChart(
     modifier: Modifier = Modifier,
     meshPackets: List<MeshPacket>,
+    selectedTime: TimeFrame,
     promptInfoDialog: () -> Unit
 ) {
-
     ChartHeader(amount = meshPackets.size)
     if (meshPackets.isEmpty()) {
         return
     }
 
+    val (oldest, newest) = remember(key1 = meshPackets) {
+        Pair(
+            meshPackets.minBy { it.rxTime },
+            meshPackets.maxBy { it.rxTime }
+        )
+    }
+    val timeDiff = newest.rxTime - oldest.rxTime
+
     TimeLabels(
-        oldest = meshPackets.first().rxTime,
-        newest = meshPackets.last().rxTime
+        oldest = oldest.rxTime,
+        newest = newest.rxTime
     )
 
     Spacer(modifier = Modifier.height(16.dp))
@@ -149,51 +156,75 @@ private fun SignalMetricsChart(
     val snrDiff = Metric.SNR.difference()
     val rssiDiff = Metric.RSSI.difference()
 
-    Box(contentAlignment = Alignment.TopStart) {
+    val scrollState = rememberScrollState()
+    val configuration = LocalConfiguration.current
+    val screenWidth = configuration.screenWidthDp
+    val dp by remember(key1 = selectedTime) {
+        mutableStateOf(selectedTime.dp(screenWidth, time = (newest.rxTime - oldest.rxTime).toLong()))
+    }
 
-        ChartOverlay(
-            modifier = modifier,
-            lineColors = List(size = 5) { graphColor },
-            labelColor = METRICS_COLORS[Metric.SNR.ordinal],
-            minValue = Metric.SNR.min,
-            maxValue = Metric.SNR.max,
-            leaveSpace = true
+    Row {
+        YAxisLabels(
+            modifier = modifier.weight(weight = .1f),
+            METRICS_COLORS[Metric.RSSI.ordinal],
+            minValue = Metric.RSSI.min,
+            maxValue = Metric.RSSI.max,
         )
-        LeftYLabels(modifier = modifier, labelColor = METRICS_COLORS[Metric.RSSI.ordinal])
+        Box(
+            contentAlignment = Alignment.TopStart,
+            modifier = Modifier
+                .horizontalScroll(state = scrollState, reverseScrolling = true)
+                .weight(1f)
+        ) {
+            HorizontalLinesOverlay(
+                modifier.width(dp),
+                lineColors = List(size = 5) { graphColor },
+                minValue = Metric.SNR.min,
+                maxValue = Metric.SNR.max
+            )
 
-        /* Plot SNR and RSSI */
-        Canvas(modifier = modifier) {
+            TimeAxisOverlay(
+                modifier.width(dp),
+                oldest = oldest.rxTime,
+                newest = newest.rxTime,
+                selectedTime.lineInterval()
+            )
 
-            val height = size.height
-            val width = size.width - 28.dp.toPx()
-            val spacing = LEFT_LABEL_SPACING.dp.toPx()
-            val spacePerEntry = (width - spacing) / meshPackets.size
+            /* Plot SNR and RSSI */
+            Canvas(modifier = modifier.width(dp)) {
+                val width = size.width
+                /* Plot */
+                for (packet in meshPackets) {
 
-            /* Plot */
-            val dataPointRadius = 2.dp.toPx()
-            for ((i, packet) in meshPackets.withIndex()) {
+                    val xRatio = (packet.rxTime - oldest.rxTime).toFloat() / timeDiff
+                    val x = xRatio * width
 
-                val x = spacing + i * spacePerEntry
+                    /* SNR */
+                    plotPoint(
+                        drawContext = drawContext,
+                        color = METRICS_COLORS[Metric.SNR.ordinal],
+                        x = x,
+                        value = packet.rxSnr - Metric.SNR.min,
+                        divisor = snrDiff
+                    )
 
-                /* SNR */
-                val snrRatio = (packet.rxSnr - Metric.SNR.min) / snrDiff
-                val ySNR = height - (snrRatio * height)
-                drawCircle(
-                    color = METRICS_COLORS[Metric.SNR.ordinal],
-                    radius = dataPointRadius,
-                    center = Offset(x, ySNR)
-                )
-
-                /* RSSI */
-                val rssiRatio = (packet.rxRssi - Metric.RSSI.min) / rssiDiff
-                val yRssi = height - (rssiRatio * height)
-                drawCircle(
-                    color = METRICS_COLORS[Metric.RSSI.ordinal],
-                    radius = dataPointRadius,
-                    center = Offset(x, yRssi)
-                )
+                    /* RSSI */
+                    plotPoint(
+                        drawContext = drawContext,
+                        color = METRICS_COLORS[Metric.RSSI.ordinal],
+                        x = x,
+                        value = packet.rxRssi - Metric.RSSI.min,
+                        divisor = rssiDiff
+                    )
+                }
             }
         }
+        YAxisLabels(
+            modifier = modifier.weight(weight = .1f),
+            METRICS_COLORS[Metric.SNR.ordinal],
+            minValue = Metric.SNR.min,
+            maxValue = Metric.SNR.max,
+        )
     }
 
     Spacer(modifier = Modifier.height(16.dp))
@@ -203,48 +234,6 @@ private fun SignalMetricsChart(
     Spacer(modifier = Modifier.height(16.dp))
 }
 
-/**
- * Draws a set of Y labels on the left side of the graph.
- * Currently only used for the RSSI labels.
- */
-@Composable
-private fun LeftYLabels(
-    modifier: Modifier,
-    labelColor: Color,
-) {
-    val range = Metric.RSSI.difference()
-    val verticalSpacing = range / LINE_LIMIT
-    val density = LocalDensity.current
-    Canvas(modifier = modifier) {
-
-        val height = size.height
-
-        /* Y Labels */
-
-        val textPaint = Paint().apply {
-            color = labelColor.toArgb()
-            textAlign = Paint.Align.LEFT
-            textSize = density.run { 12.dp.toPx() }
-            typeface = setTypeface(Typeface.create(Typeface.DEFAULT, Typeface.BOLD))
-            alpha = TEXT_PAINT_ALPHA
-        }
-        drawContext.canvas.nativeCanvas.apply {
-            var label = Metric.RSSI.min
-            for (i in 0..LINE_LIMIT) {
-                val ratio = (label - Metric.RSSI.min) / range
-                val y = height - (ratio * height)
-                drawText(
-                    "${label.toInt()}",
-                    4.dp.toPx(),
-                    y + 4.dp.toPx(),
-                    textPaint
-                )
-                label += verticalSpacing
-            }
-        }
-    }
-}
-
 @Composable
 private fun SignalMetricsCard(meshPacket: MeshPacket) {
     val time = meshPacket.rxTime * MS_PER_SEC

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

@@ -17,6 +17,7 @@
 
 package com.geeksville.mesh.util
 
+import android.content.res.Resources
 import androidx.compose.ui.graphics.Path
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Color
@@ -25,6 +26,8 @@ import com.geeksville.mesh.TelemetryProtos.Telemetry
 
 object GraphUtil {
 
+    val RADIUS = Resources.getSystem().displayMetrics.density * 2
+
     /**
      * @param value Must be zero-scaled before passing.
      * @param divisor The range for the data set.
@@ -32,7 +35,6 @@ object GraphUtil {
     fun plotPoint(
         drawContext: DrawContext,
         color: Color,
-        radius: Float,
         x: Float,
         value: Float,
         divisor: Float,
@@ -42,7 +44,7 @@ object GraphUtil {
         val y = height - (ratio * height)
         drawContext.canvas.drawCircle(
             center = Offset(x, y),
-            radius = radius,
+            radius = RADIUS,
             paint = androidx.compose.ui.graphics.Paint().apply { this.color = color }
         )
     }