--- /dev/null
+/*
+ * Copyright (C) 2010 ZXing authors
+ *
+ * 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 com.google.zxing.client.android;
+
+import android.os.IBinder;
+import android.util.Log;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+/**
+ * This class is used to activate the weak light on some camera phones (not flash)
+ * in order to illuminate surfaces for scanning. There is no official way to do this,
+ * but, classes which allow access to this function still exist on some devices.
+ * This therefore proceeds through a great deal of reflection.
+ *
+ * See <a href="http://almondmendoza.com/2009/01/05/changing-the-screen-brightness-programatically/">
+ * http://almondmendoza.com/2009/01/05/changing-the-screen-brightness-programatically/</a> and
+ * <a href="http://code.google.com/p/droidled/source/browse/trunk/src/com/droidled/demo/DroidLED.java">
+ * http://code.google.com/p/droidled/source/browse/trunk/src/com/droidled/demo/DroidLED.java</a>.
+ */
+final class FlashlightManager {
+
+ private static final String TAG = FlashlightManager.class.getName();
+
+ private static Object iHardwareService;
+ private static Method setFlashEnabledMethod;
+ static {
+ iHardwareService = getHardwareService();
+ setFlashEnabledMethod = getSetFlashEnabledMethod(iHardwareService);
+ if (iHardwareService == null) {
+ Log.i(TAG, "This device does supports control of a flashlight");
+ } else {
+ Log.i(TAG, "This device does not support control of a flashlight");
+ }
+ }
+
+ private FlashlightManager() {
+ }
+
+ private static Object getHardwareService() {
+ Class<?> serviceManagerClass = maybeForName("android.os.ServiceManager");
+ if (serviceManagerClass == null) {
+ return null;
+ }
+
+ Method getServiceMethod = maybeGetMethod(serviceManagerClass, "getService", String.class);
+ if (getServiceMethod == null) {
+ return null;
+ }
+
+ Object hardwareService = invoke(getServiceMethod, null, "hardware");
+ if (hardwareService == null) {
+ return null;
+ }
+
+ Class<?> iHardwareServiceStubClass = maybeForName("android.os.IHardwareService$Stub");
+ if (iHardwareServiceStubClass == null) {
+ return null;
+ }
+
+ Method asInterfaceMethod = maybeGetMethod(iHardwareServiceStubClass, "asInterface", IBinder.class);
+ if (asInterfaceMethod == null) {
+ return null;
+ }
+
+ return invoke(asInterfaceMethod, null, hardwareService);
+ }
+
+ private static Method getSetFlashEnabledMethod(Object iHardwareService) {
+ if (iHardwareService == null) {
+ return null;
+ }
+ Class<?> proxyClass = iHardwareService.getClass();
+ return maybeGetMethod(proxyClass, "setFlashlightEnabled", boolean.class);
+ }
+
+ private static Class<?> maybeForName(String name) {
+ try {
+ return Class.forName(name);
+ } catch (ClassNotFoundException cnfe) {
+ // OK
+ return null;
+ } catch (RuntimeException re) {
+ Log.w(TAG, "Unexpected error while finding class " + name, re);
+ return null;
+ }
+ }
+
+ private static Method maybeGetMethod(Class<?> clazz, String name, Class<?>... argClasses) {
+ try {
+ return clazz.getMethod(name, argClasses);
+ } catch (NoSuchMethodException nsme) {
+ // OK
+ return null;
+ } catch (RuntimeException re) {
+ Log.w(TAG, "Unexpected error while finding method " + name, re);
+ return null;
+ }
+ }
+
+ private static Object invoke(Method method, Object instance, Object... args) {
+ try {
+ return method.invoke(instance, args);
+ } catch (IllegalAccessException e) {
+ Log.w(TAG, "Unexpected error while invoking " + method, e);
+ return null;
+ } catch (InvocationTargetException e) {
+ Log.w(TAG, "Unexpected error while invoking " + method, e.getCause());
+ return null;
+ } catch (RuntimeException re) {
+ Log.w(TAG, "Unexpected error while invoking " + method, re);
+ return null;
+ }
+ }
+
+ static void enableFlashlight() {
+ setFlashlight(true);
+ }
+
+ static void disableFlashlight() {
+ setFlashlight(false);
+ }
+
+ private static void setFlashlight(boolean active) {
+ if (iHardwareService != null) {
+ invoke(setFlashEnabledMethod, iHardwareService, active);
+ }
+ }
+
+}