feat(scalable content): add code snippets

compose/snippets/src/main/java/com/example/compose/snippets/accessibility/ScalableContentSnippets.kt

@@ -0,0 +1,196 @@
+/*
+ * 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.accessibility
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.gestures.TransformableState
+import androidx.compose.foundation.gestures.transformable
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+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.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Person
+import androidx.compose.material3.Card
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Switch
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.dp
+
+// [START android_compose_accessibility_scalable_content_density_scaling]
+private class DensityScalingState(
+    // Note: For accessibility, typical min/max values are ~0.75x and ~3.5x.
+    private val minScale: Float = 0.75f,
+    private val maxScale: Float = 3.5f,
+    private val currentDensity: Density
+) {
+    val transformableState = TransformableState { zoomChange, _, _ ->
+        scaleFactor.floatValue =
+            (scaleFactor.floatValue * zoomChange).coerceIn(minScale, maxScale)
+    }
+    val scaleFactor = mutableFloatStateOf(1f)
+    fun scaledDensity(): Density {
+        return Density(
+            currentDensity.density * scaleFactor.floatValue,
+            currentDensity.fontScale
+        )
+    }
+}
+
+// [START_EXCLUDE silent]
+@Preview
+// [END_EXCLUDE silent]
+@Composable
+fun DensityScalingSample() {
+    val currentDensity = LocalDensity.current
+    val scaleState =
+        remember(currentDensity) { DensityScalingState(currentDensity = currentDensity) }
+
+    Box(
+        modifier = Modifier
+            .fillMaxSize()
+            .transformable(state = scaleState.transformableState),
+        contentAlignment = Alignment.TopCenter
+    ) {
+        CompositionLocalProvider(
+            LocalDensity provides scaleState.scaledDensity()
+        ) {
+            DemoCard()
+        }
+    }
+}
+// [END android_compose_accessibility_scalable_content_density_scaling]
+
+// [START android_compose_accessibility_scalable_content_font_scaling]
+class FontScaleState(
+    // Note: For accessibility, typical min/max values are ~0.75x and ~3.5x.
+    private val minScale: Float = 0.75f,
+    private val maxScale: Float = 3.5f,
+    private val currentDensity: Density
+) {
+    val transformableState = TransformableState { zoomChange, _, _ ->
+        scaleFactor.floatValue =
+            (scaleFactor.floatValue * zoomChange).coerceIn(minScale, maxScale)
+    }
+    val scaleFactor = mutableFloatStateOf(1f)
+    fun scaledFont(): Density {
+        return Density(
+            currentDensity.density,
+            currentDensity.fontScale * scaleFactor.floatValue
+        )
+    }
+}
+
+// [START_EXCLUDE silent]
+@Preview
+// [END_EXCLUDE silent]
+@Composable
+fun FontScalingSample() {
+    val currentDensity = LocalDensity.current
+    val scaleState = remember { FontScaleState(currentDensity = currentDensity) }
+
+    Box(
+        modifier = Modifier
+            .fillMaxSize()
+            .transformable(state = scaleState.transformableState),
+        contentAlignment = Alignment.TopCenter
+    ) {
+        CompositionLocalProvider(
+            LocalDensity provides scaleState.scaledFont()
+        ) {
+            DemoCard()
+        }
+    }
+}
+// [END android_compose_accessibility_scalable_content_font_scaling]
+
+// [START android_compose_accessibility_scalable_content_demo_card]
+@Composable
+private fun DemoCard() {
+    Card(
+        modifier = Modifier
+            .width(360.dp)
+            .padding(16.dp),
+        shape = RoundedCornerShape(12.dp)
+    ) {
+        Column(
+            modifier = Modifier.padding(16.dp),
+            verticalArrangement = Arrangement.spacedBy(16.dp)
+        ) {
+            Text("Demo Card", style = MaterialTheme.typography.headlineMedium)
+            var isChecked by remember { mutableStateOf(true) }
+            Row(verticalAlignment = Alignment.CenterVertically) {
+                Text("Demo Switch", Modifier.weight(1f), style = MaterialTheme.typography.bodyLarge)
+                Switch(checked = isChecked, onCheckedChange = { isChecked = it })
+            }
+            Row(verticalAlignment = Alignment.CenterVertically) {
+                Icon(Icons.Filled.Person, "Icon", Modifier.size(32.dp))
+                Spacer(Modifier.width(8.dp))
+                Text("Demo Icon", style = MaterialTheme.typography.bodyLarge)
+            }
+            Row(
+                Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.SpaceBetween
+            ) {
+                Box(
+                    Modifier
+                        .width(100.dp)
+                        .weight(1f)
+                        .height(80.dp)
+                        .background(Color.Blue)
+                )
+                Box(
+                    Modifier
+                        .width(100.dp)
+                        .weight(1f)
+                        .height(80.dp)
+                        .background(Color.Red)
+                )
+            }
+            Text(
+                "Demo Text: Lorem ipsum dolor sit amet, consectetur adipiscing elit," +
+                    " sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
+                style = MaterialTheme.typography.bodyMedium,
+                textAlign = TextAlign.Justify
+            )
+        }
+    }
+}
+// [END android_compose_accessibility_scalable_content_demo_card]