Adds DrawArea sample

compose/snippets/src/main/java/com/example/compose/snippets/SnippetsActivity.kt

@@ -61,6 +61,7 @@ import com.example.compose.snippets.landing.LandingScreen
 import com.example.compose.snippets.layouts.PagerExamples
 import com.example.compose.snippets.navigation.Destination
 import com.example.compose.snippets.navigation.TopComponentsDestination
+import com.example.compose.snippets.touchinput.pointerinput.DrawArea
 import com.example.compose.snippets.ui.theme.SnippetsTheme
 
 class SnippetsActivity : ComponentActivity() {
@@ -94,6 +95,7 @@ class SnippetsActivity : ComponentActivity() {
                                     Destination.ShapesExamples -> ApplyPolygonAsClipImage()
                                     Destination.SharedElementExamples -> PlaceholderSizeAnimated_Demo()
                                     Destination.PagerExamples -> PagerExamples()
+                                    Destination.DrawAreaSample -> DrawArea()
                                 }
                             }
                         }

compose/snippets/src/main/java/com/example/compose/snippets/navigation/Destination.kt

@@ -24,7 +24,8 @@ enum class Destination(val route: String, val title: String) {
     ScreenshotExample("screenshotExample", "Screenshot Examples"),
     ShapesExamples("shapesExamples", "Shapes Examples"),
     SharedElementExamples("sharedElement", "Shared elements"),
-    PagerExamples("pagerExamples", "Pager examples")
+    PagerExamples("pagerExamples", "Pager examples"),
+    DrawAreaSample("drawAreaSample", "Draw Area Sample")
 }
 
 // Enum class for compose components navigation screen.

compose/snippets/src/main/java/com/example/compose/snippets/touchinput/pointerinput/DrawAreaSample.kt

@@ -0,0 +1,151 @@
+/*
+ * Copyright 2025 The Android Open Source Project
+ *
+ * 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
+ *
+ *     https://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 com.example.compose.snippets.touchinput.pointerinput
+
+import android.os.Bundle
+import android.util.Log
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clipToBounds
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.StrokeCap
+import androidx.compose.ui.graphics.drawscope.Stroke
+import androidx.compose.ui.input.pointer.pointerInteropFilter
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewmodel.compose.viewModel
+
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * 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
+ *
+ *     https://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.
+ */
+
+/**
+ * This sample demonstrates a Composable function that provides a canvas for drawing and
+ * processes touch input events to draw lines. It uses a ViewModel to manage the drawing state.
+ *
+ * Gradle Dependencies:
+ * implementation "androidx.compose.ui:ui:1.x.x"
+ * implementation "androidx.compose.foundation:foundation:1.x.x"
+ * implementation "androidx.lifecycle:lifecycle-viewmodel-compose:2.x.x"
+ *
+ * Manifest Permissions:
+ * None
+ */
+
+const val TAG = "DrawAreaSample"
+
+class DrawAreaSampleActivity : ComponentActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            Column(Modifier.fillMaxSize().background(Color.LightGray)) {
+                DrawArea(modifier = Modifier.weight(1f))
+            }
+        }
+    }
+}
+
+// [START android_snippets_compose_draw_area_sample]
+@Composable
+@OptIn(ExperimentalComposeUiApi::class)
+fun DrawArea(modifier: Modifier = Modifier, viewModel: DrawAreaViewModel = viewModel()) {
+    Canvas(
+        modifier = modifier
+            .clipToBounds()
+            .pointerInteropFilter { motionEvent ->
+                viewModel.processMotionEvent(motionEvent)
+                true
+            }
+    ) {
+        viewModel.paths.forEach { path ->
+            drawPath(
+                path = path,
+                color = Color.Black,
+                style = Stroke(width = 8f, cap = StrokeCap.Round)
+            )
+        }
+    }
+}
+// [END android_snippets_compose_draw_area_sample]
+
+class DrawAreaViewModel : ViewModel() {
+    private var currentPath = Path()
+    val paths: SnapshotStateList<Path> = mutableStateListOf()
+
+    @OptIn(ExperimentalComposeUiApi::class)
+    fun processMotionEvent(motionEvent: android.view.MotionEvent) {
+        when (motionEvent.actionMasked) {
+            android.view.MotionEvent.ACTION_DOWN -> {
+                Log.d(TAG, "ACTION_DOWN at (${motionEvent.x}, ${motionEvent.y})")
+                currentPath = Path().apply {
+                    moveTo(motionEvent.x, motionEvent.y)
+                }
+                paths.add(currentPath)
+            }
+            android.view.MotionEvent.ACTION_MOVE -> {
+                Log.d(TAG, "ACTION_MOVE at (${motionEvent.x}, ${motionEvent.y})")
+                // To trigger recomposition, we need to replace the path object
+                // in the list with a new one.
+                val newPath = Path().apply {
+                    addPath(currentPath)
+                    lineTo(motionEvent.x, motionEvent.y)
+                }
+
+                // Replace the last path with the updated one.
+                if (paths.isNotEmpty()) {
+                    paths[paths.size - 1] = newPath
+                }
+                currentPath = newPath
+            }
+            android.view.MotionEvent.ACTION_UP,
+            android.view.MotionEvent.ACTION_CANCEL -> {
+                Log.d(TAG, "ACTION_UP/CANCEL")
+                // Path is complete, no further action needed
+            }
+        }
+    }
+}
+
+@Preview(showBackground = true)
+@Composable
+fun PreviewDrawArea() {
+    Column(Modifier.fillMaxSize().background(Color.LightGray)) {
+        DrawArea(modifier = Modifier.weight(1f))
+    }
+}