[camera] android-rework part 4: Android flash and zoom features

packages/camera/camera/android/build.gradle

@@ -49,7 +49,7 @@ android {
 dependencies {
     compileOnly 'androidx.annotation:annotation:1.1.0'
     testImplementation 'junit:junit:4.12'
-    testImplementation 'org.mockito:mockito-core:3.5.13'
+    testImplementation 'org.mockito:mockito-inline:3.5.13'
     testImplementation 'androidx.test:core:1.3.0'
     testImplementation 'org.robolectric:robolectric:4.3'
 }

packages/camera/camera/android/src/main/java/io/flutter/plugins/camera/features/flash/FlashFeature.java

@@ -0,0 +1,75 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.camera.features.flash;
+
+import android.hardware.camera2.CaptureRequest;
+import io.flutter.plugins.camera.CameraProperties;
+import io.flutter.plugins.camera.features.CameraFeature;
+
+/** Controls the flash configuration on the {@link android.hardware.camera2} API. */
+public class FlashFeature extends CameraFeature<FlashMode> {
+  private FlashMode currentSetting = FlashMode.auto;
+
+  /**
+   * Creates a new instance of the {@link FlashFeature}.
+   *
+   * @param cameraProperties Collection of characteristics for the current camera device.
+   */
+  public FlashFeature(CameraProperties cameraProperties) {
+    super(cameraProperties);
+  }
+
+  @Override
+  public String getDebugName() {
+    return "FlashFeature";
+  }
+
+  @Override
+  public FlashMode getValue() {
+    return currentSetting;
+  }
+
+  @Override
+  public void setValue(FlashMode value) {
+    this.currentSetting = value;
+  }
+
+  @Override
+  public boolean checkIsSupported() {
+    Boolean available = cameraProperties.getFlashInfoAvailable();
+    return available != null && available;
+  }
+
+  @Override
+  public void updateBuilder(CaptureRequest.Builder requestBuilder) {
+    if (!checkIsSupported()) {
+      return;
+    }
+
+    switch (currentSetting) {
+      case off:
+        requestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
+        requestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
+        break;
+
+      case always:
+        requestBuilder.set(
+            CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_ALWAYS_FLASH);
+        requestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
+        break;
+
+      case torch:
+        requestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
+        requestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_TORCH);
+        break;
+
+      case auto:
+        requestBuilder.set(
+            CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
+        requestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);
+        break;
+    }
+  }
+}

packages/camera/camera/android/src/main/java/io/flutter/plugins/camera/features/flash/FlashMode.java

@@ -0,0 +1,31 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.camera.features.flash;
+
+// Mirrors flash_mode.dart
+public enum FlashMode {
+  off("off"),
+  auto("auto"),
+  always("always"),
+  torch("torch");
+
+  private final String strValue;
+
+  FlashMode(String strValue) {
+    this.strValue = strValue;
+  }
+
+  public static FlashMode getValueForString(String modeStr) {
+    for (FlashMode value : values()) {
+      if (value.strValue.equals(modeStr)) return value;
+    }
+    return null;
+  }
+
+  @Override
+  public String toString() {
+    return strValue;
+  }
+}

packages/camera/camera/android/src/main/java/io/flutter/plugins/camera/features/zoomlevel/ZoomLevelFeature.java

@@ -0,0 +1,94 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.camera.features.zoomlevel;
+
+import android.graphics.Rect;
+import android.hardware.camera2.CaptureRequest;
+import io.flutter.plugins.camera.CameraProperties;
+import io.flutter.plugins.camera.features.CameraFeature;
+
+/** Controls the zoom configuration on the {@link android.hardware.camera2} API. */
+public class ZoomLevelFeature extends CameraFeature<Float> {
+  private static final float MINIMUM_ZOOM_LEVEL = 1.0f;
+  private final boolean hasSupport;
+  private final Rect sensorArraySize;
+  private Float currentSetting = MINIMUM_ZOOM_LEVEL;
+  private Float maximumZoomLevel = MINIMUM_ZOOM_LEVEL;
+
+  /**
+   * Creates a new instance of the {@link ZoomLevelFeature}.
+   *
+   * @param cameraProperties Collection of characteristics for the current camera device.
+   */
+  public ZoomLevelFeature(CameraProperties cameraProperties) {
+    super(cameraProperties);
+
+    sensorArraySize = cameraProperties.getSensorInfoActiveArraySize();
+
+    if (sensorArraySize == null) {
+      maximumZoomLevel = MINIMUM_ZOOM_LEVEL;
+      hasSupport = false;
+      return;
+    }
+
+    Float maxDigitalZoom = cameraProperties.getScalerAvailableMaxDigitalZoom();
+    maximumZoomLevel =
+        ((maxDigitalZoom == null) || (maxDigitalZoom < MINIMUM_ZOOM_LEVEL))
+            ? MINIMUM_ZOOM_LEVEL
+            : maxDigitalZoom;
+
+    hasSupport = (Float.compare(maximumZoomLevel, MINIMUM_ZOOM_LEVEL) > 0);
+  }
+
+  @Override
+  public String getDebugName() {
+    return "ZoomLevelFeature";
+  }
+
+  @Override
+  public Float getValue() {
+    return currentSetting;
+  }
+
+  @Override
+  public void setValue(Float value) {
+    currentSetting = value;
+  }
+
+  @Override
+  public boolean checkIsSupported() {
+    return hasSupport;
+  }
+
+  @Override
+  public void updateBuilder(CaptureRequest.Builder requestBuilder) {
+    if (!checkIsSupported()) {
+      return;
+    }
+
+    final Rect computedZoom =
+        ZoomUtils.computeZoom(
+            currentSetting, sensorArraySize, MINIMUM_ZOOM_LEVEL, maximumZoomLevel);
+    requestBuilder.set(CaptureRequest.SCALER_CROP_REGION, computedZoom);
+  }
+
+  /**
+   * Gets the minimum supported zoom level.
+   *
+   * @return The minimum zoom level.
+   */
+  public float getMinimumZoomLevel() {
+    return MINIMUM_ZOOM_LEVEL;
+  }
+
+  /**
+   * Gets the maximum supported zoom level.
+   *
+   * @return The maximum zoom level.
+   */
+  public float getMaximumZoomLevel() {
+    return maximumZoomLevel;
+  }
+}

packages/camera/camera/android/src/main/java/io/flutter/plugins/camera/features/zoomlevel/ZoomUtils.java

@@ -0,0 +1,40 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.camera.features.zoomlevel;
+
+import android.graphics.Rect;
+import androidx.annotation.NonNull;
+import androidx.core.math.MathUtils;
+
+/**
+ * Utility class containing methods that assist with zoom features in the {@link
+ * android.hardware.camera2} API.
+ */
+final class ZoomUtils {
+
+  /**
+   * Computes an image sensor area based on the supplied zoom settings.
+   *
+   * <p>The returned image sensor area can be applied to the {@link android.hardware.camera2} API in
+   * order to control zoom levels.
+   *
+   * @param zoom The desired zoom level.
+   * @param sensorArraySize The current area of the image sensor.
+   * @param minimumZoomLevel The minimum supported zoom level.
+   * @param maximumZoomLevel The maximim supported zoom level.
+   * @return An image sensor area based on the supplied zoom settings
+   */
+  static Rect computeZoom(
+      float zoom, @NonNull Rect sensorArraySize, float minimumZoomLevel, float maximumZoomLevel) {
+    final float newZoom = MathUtils.clamp(zoom, minimumZoomLevel, maximumZoomLevel);
+
+    final int centerX = sensorArraySize.width() / 2;
+    final int centerY = sensorArraySize.height() / 2;
+    final int deltaX = (int) ((0.5f * sensorArraySize.width()) / newZoom);
+    final int deltaY = (int) ((0.5f * sensorArraySize.height()) / newZoom);
+
+    return new Rect(centerX - deltaX, centerY - deltaY, centerX + deltaX, centerY + deltaY);
+  }
+}