Improve bar chart code (#121)

dautovicharis · Jun 17, 2024 · 2d6228d · 2d6228d
1 parent 9765d39
commit 2d6228d
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Showing 2 changed files with 87 additions and 43 deletions.
diff --git a/charts/src/commonMain/kotlin/io/github/dautovicharis/charts/internal/barchart/BarChart.kt b/charts/src/commonMain/kotlin/io/github/dautovicharis/charts/internal/barchart/BarChart.kt
@@ -1,6 +1,7 @@
 package io.github.dautovicharis.charts.internal.barchart
 
 import androidx.compose.animation.core.Animatable
+import androidx.compose.animation.core.AnimationVector1D
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.gestures.detectDragGestures
 import androidx.compose.runtime.Composable
@@ -11,6 +12,8 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.util.lerp
 import io.github.dautovicharis.charts.internal.AnimationSpec
@@ -63,30 +66,52 @@ internal fun BarChart(
                 onValueChanged(NO_SELECTION)
             }
         )
-    }) {
-        val baselineY = size.height * (maxValue / (maxValue - minValue))
-        val dataSize = chartData.points.size
+    }, onDraw = {
+        drawBars(
+            style = style,
+            size = size,
+            chartData = chartData,
+            progress = progress,
+            selectedIndex = selectedIndex,
+            barColor = barColor,
+            maxValue = maxValue,
+            minValue = minValue
+        )
+    })
+}
+
+private fun DrawScope.drawBars(
+    style: BarChartStyle,
+    size: Size,
+    chartData: ChartData,
+    progress: List<Animatable<Float, AnimationVector1D>>,
+    selectedIndex: Int,
+    barColor: Color,
+    maxValue: Double,
+    minValue: Double
+) {
+    val baselineY = size.height * (maxValue / (maxValue - minValue))
+    val dataSize = chartData.points.size
 
-        chartData.points.forEachIndexed { index, value ->
-            val spacing = style.space.toPx()
-            val barWidth = (size.width - spacing * (dataSize - 1)) / dataSize
+    chartData.points.forEachIndexed { index, value ->
+        val spacing = style.space.toPx()
+        val barWidth = (size.width - spacing * (dataSize - 1)) / dataSize
 
-            val finalBarHeight = size.height * (abs(value) / (maxValue - minValue))
-            val barHeight = lerp(0f, finalBarHeight.toFloat(), progress[index].value)
+        val finalBarHeight = size.height * (abs(value) / (maxValue - minValue))
+        val barHeight = lerp(0f, finalBarHeight.toFloat(), progress[index].value)
 
-            val top = if (value >= 0) baselineY - barHeight else baselineY
-            val left = (barWidth + spacing) * index
+        val top = if (value >= 0) baselineY - barHeight else baselineY
+        val left = (barWidth + spacing) * index
 
-            val selectedBarScale = if (index == selectedIndex) MAX_SCALE else DEFAULT_SCALE
+        val selectedBarScale = if (index == selectedIndex) MAX_SCALE else DEFAULT_SCALE
 
-            drawRect(
-                color = barColor,
-                topLeft = Offset(x = left, y = top.toFloat()),
-                size = Size(
-                    width = barWidth * selectedBarScale,
-                    height = barHeight * selectedBarScale
-                )
+        drawRect(
+            color = barColor,
+            topLeft = Offset(x = left, y = top.toFloat()),
+            size = Size(
+                width = barWidth * selectedBarScale,
+                height = barHeight * selectedBarScale
             )
-        }
+        )
     }
 }
diff --git a/...monMain/kotlin/io/github/dautovicharis/charts/internal/barstackedchart/BarStackedChart.kt b/...monMain/kotlin/io/github/dautovicharis/charts/internal/barstackedchart/BarStackedChart.kt
@@ -1,6 +1,7 @@
 package io.github.dautovicharis.charts.internal.barstackedchart
 
 import androidx.compose.animation.core.Animatable
+import androidx.compose.animation.core.AnimationVector1D
 import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.gestures.detectDragGestures
 import androidx.compose.runtime.Composable
@@ -12,6 +13,7 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.util.lerp
 import io.github.dautovicharis.charts.internal.AnimationSpec
@@ -33,6 +35,7 @@ internal fun StackedBarChart(
     val progress = remember {
         data.items.map { Animatable(0f) }
     }
+    var selectedIndex by remember { mutableIntStateOf(-1) }
 
     progress.forEachIndexed { index, _ ->
         LaunchedEffect(index) {
@@ -43,8 +46,6 @@ internal fun StackedBarChart(
         }
     }
 
-    var selectedIndex by remember { mutableIntStateOf(-1) }
-
     Canvas(
         modifier = style.modifier.pointerInput(Unit) {
             detectDragGestures(
@@ -62,32 +63,50 @@ internal fun StackedBarChart(
                     onValueChanged(NO_SELECTION)
                 }
             )
+        }, onDraw = {
+            drawBars(
+                style = style,
+                size = size,
+                data = data,
+                progress = progress,
+                selectedIndex = selectedIndex,
+                colors = colors
+            )
         }
-    ) {
-        val totalMaxValue = data.items.maxOf { it.item.points.sum() }
-        val spacing = style.space.toPx()
-        val barWidth = (size.width - spacing * (data.items.size - 1)) / data.items.size
+    )
+}
 
-        data.items.forEachIndexed { index, item ->
-            var topOffset = size.height
-            val selectedBarScale = if (index == selectedIndex) MAX_SCALE else DEFAULT_SCALE
-            item.item.points.forEachIndexed { dataIndex, value ->
-                val height = lerp(
-                    0f,
-                    (value.toFloat() / totalMaxValue.toFloat()) * size.height,
-                    progress[index].value
-                )
-                topOffset -= height
+private fun DrawScope.drawBars(
+    style: StackedBarChartStyle,
+    size: Size,
+    data: MultiChartData,
+    progress: List<Animatable<Float, AnimationVector1D>>,
+    selectedIndex: Int,
+    colors: List<Color>
+) {
+    val totalMaxValue = data.items.maxOf { it.item.points.sum() }
+    val spacing = style.space.toPx()
+    val barWidth = (size.width - spacing * (data.items.size - 1)) / data.items.size
 
-                drawRect(
-                    color = colors[dataIndex],
-                    topLeft = Offset(x = index * (barWidth + spacing), y = topOffset),
-                    size = Size(
-                        width = barWidth * selectedBarScale,
-                        height = height * selectedBarScale
-                    )
+    data.items.forEachIndexed { index, item ->
+        var topOffset = size.height
+        val selectedBarScale = if (index == selectedIndex) MAX_SCALE else DEFAULT_SCALE
+        item.item.points.forEachIndexed { dataIndex, value ->
+            val height = lerp(
+                0f,
+                (value.toFloat() / totalMaxValue.toFloat()) * size.height,
+                progress[index].value
+            )
+            topOffset -= height
+
+            drawRect(
+                color = colors[dataIndex],
+                topLeft = Offset(x = index * (barWidth + spacing), y = topOffset),
+                size = Size(
+                    width = barWidth * selectedBarScale,
+                    height = height * selectedBarScale
                 )
-            }
+            )
         }
     }
 }