Simple live waveform implementation.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/media/DrawScopeWaveformExtensions.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.designsystem.components.media
+
+import androidx.compose.ui.geometry.CornerRadius
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.graphics.Brush
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.drawscope.Fill
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import kotlinx.collections.immutable.ImmutableList
+import kotlin.math.max
+
+fun DrawScope.drawWaveform(
+    waveformData: ImmutableList<Float>,
+    canvasSize: DpSize,
+    brush: Brush,
+    minimumGraphAmplitude: Float = 2F,
+    lineWidth: Dp = 2.dp,
+    linePadding: Dp = 2.dp,
+) {
+    val centerY = canvasSize.height.toPx() / 2
+    val cornerRadius = lineWidth / 2
+    waveformData.forEachIndexed { index, amplitude ->
+        val drawingAmplitude = max(minimumGraphAmplitude, amplitude * (canvasSize.height.toPx() - 2))
+        drawRoundRect(
+            brush = brush,
+            topLeft = Offset(
+                x = index * (linePadding + lineWidth).toPx(),
+                y = centerY - drawingAmplitude / 2
+            ),
+            size = Size(
+                width = lineWidth.toPx(),
+                height = drawingAmplitude
+            ),
+            cornerRadius = CornerRadius(cornerRadius.toPx(), cornerRadius.toPx()),
+            style = Fill
+        )
+    }
+}

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/media/WaveformPlaybackView.kt

@@ -48,7 +48,6 @@ import io.element.android.libraries.designsystem.preview.PreviewsDayNight
 import io.element.android.libraries.theme.ElementTheme
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.toPersistentList
-import kotlin.math.max
 
 private const val DEFAULT_GRAPHICS_LAYER_ALPHA: Float = 0.99F
 @OptIn(ExperimentalComposeUiApi::class)
@@ -64,7 +63,6 @@ fun WaveformPlaybackView(
     cursorBrush: Brush  = SolidColor(ElementTheme.colors.iconAccentTertiary),
     lineWidth: Dp = 2.dp,
     linePadding: Dp = 2.dp,
-    minimumGraphAmplitude: Float = 2F,
 ) {
     val seekProgress = remember { mutableStateOf<Float?>(null) }
     var canvasSize by remember { mutableStateOf(DpSize(0.dp, 0.dp)) }
@@ -121,22 +119,13 @@ fun WaveformPlaybackView(
         canvasSizePx = size
         val centerY = canvasSize.height.toPx() / 2
         val cornerRadius = lineWidth / 2
-        normalizedWaveformData.forEachIndexed { index, amplitude ->
-            val drawingAmplitude = max(minimumGraphAmplitude, amplitude * (canvasSize.height.toPx() - 2))
-            drawRoundRect(
-                brush = brush,
-                topLeft = Offset(
-                    x = index * (linePadding + lineWidth).toPx(),
-                    y = centerY - drawingAmplitude / 2
-                ),
-                size = Size(
-                    width = lineWidth.toPx(),
-                    height = drawingAmplitude
-                ),
-                cornerRadius = CornerRadius(cornerRadius.toPx(), cornerRadius.toPx()),
-                style = Fill
-            )
-        }
+        drawWaveform(
+            waveformData = normalizedWaveformData,
+            canvasSize = canvasSize,
+            brush = brush,
+            lineWidth = lineWidth,
+            linePadding = linePadding
+        )
         drawRect(
             brush = progressBrush,
             size = Size(