Merge pull request #459 from xamarin/feature/issue-348

GH-348: Add Barometer Sensor API

DeviceTests/DeviceTests.Shared/Barometer_Shared.cs

@@ -0,0 +1,84 @@
+using System.Threading.Tasks;
+using Xamarin.Essentials;
+using Xunit;
+
+namespace DeviceTests
+{
+    public class Barometer_Tests
+    {
+        [Fact]
+        public void IsSupported()
+            => Assert.Equal(HardwareSupport.HasBarometer, Barometer.IsSupported);
+
+        [Fact]
+        [Trait(Traits.Hardware.Barometer, Traits.FeatureSupport.Supported)]
+        public async Task Monitor()
+        {
+            // TODO: the test runner app (UI version) should do this, until then...
+            if (!HardwareSupport.HasBarometer)
+                return;
+
+            var tcs = new TaskCompletionSource<BarometerData>();
+
+            Barometer.ReadingChanged += Barometer_ReadingChanged;
+            void Barometer_ReadingChanged(object sender, BarometerChangedEventArgs e)
+            {
+                tcs.TrySetResult(e.Reading);
+            }
+            Barometer.Start(SensorSpeed.UI);
+
+            var d = await tcs.Task;
+
+            Assert.True(d.Pressure >= 0);
+            Barometer.Stop();
+            Barometer.ReadingChanged -= Barometer_ReadingChanged;
+        }
+
+        [Fact]
+        [Trait(Traits.Hardware.Barometer, Traits.FeatureSupport.Supported)]
+        public async Task IsMonitoring()
+        {
+            // TODO: the test runner app (UI version) should do this, until then...
+            if (!HardwareSupport.HasBarometer)
+                return;
+
+            var tcs = new TaskCompletionSource<BarometerData>();
+            Barometer.ReadingChanged += Barometer_ReadingChanged;
+            void Barometer_ReadingChanged(object sender, BarometerChangedEventArgs e)
+            {
+                tcs.TrySetResult(e.Reading);
+            }
+            Barometer.Start(SensorSpeed.UI);
+
+            var d = await tcs.Task;
+            Assert.True(Barometer.IsMonitoring);
+
+            Barometer.Stop();
+            Barometer.ReadingChanged -= Barometer_ReadingChanged;
+        }
+
+        [Fact]
+        [Trait(Traits.Hardware.Barometer, Traits.FeatureSupport.Supported)]
+        public async Task Stop_Monitor()
+        {
+            // TODO: the test runner app (UI version) should do this, until then...
+            if (!HardwareSupport.HasBarometer)
+                return;
+
+            var tcs = new TaskCompletionSource<BarometerData>();
+            Barometer.ReadingChanged += Barometer_ReadingChanged;
+            void Barometer_ReadingChanged(object sender, BarometerChangedEventArgs e)
+            {
+                tcs.TrySetResult(e.Reading);
+            }
+            Barometer.Start(SensorSpeed.UI);
+
+            var d = await tcs.Task;
+
+            Barometer.Stop();
+            Barometer.ReadingChanged -= Barometer_ReadingChanged;
+
+            Assert.False(Barometer.IsMonitoring);
+        }
+    }
+}

DeviceTests/DeviceTests.Shared/HardwareSupport.cs

@@ -74,5 +74,16 @@ static class HardwareSupport
             // TODO: most UWP devices don't have a camera lamp (mobile devices do, we we don't care about those)
             false;
 #endif
+
+        public static bool HasBarometer =>
+#if __ANDROID__
+      true;
+#elif __IOS__
+            // iphone 6 and never have a barometer. looking in how to test this.
+            Xamarin.Essentials.DeviceInfo.DeviceType == Xamarin.Essentials.DeviceType.Physical;
+#elif WINDOWS_UWP
+            // TODO: most UWP devices don't have a barometer (mobile devices do, we we don't care about those)
+            false;
+#endif
     }
 }

DeviceTests/DeviceTests.Shared/Traits.cs

@@ -14,6 +14,7 @@ static class Traits
         internal static class Hardware
         {
             public const string Accelerometer = "HardwareAccelerometer";
+            public const string Barometer = "HardwareBarometer";
             public const string Compass = "HardwareCompass";
             public const string Gyroscope = "HardwareGyroscope";
             public const string Magnetometer = "HardwareMagnetometer";

Samples/Samples/View/AllSensorsPage.xaml

@@ -141,7 +141,7 @@
                     <Button Grid.Row="5" Grid.Column="1" Text="Stop" Command="{Binding StopCommand}"
                             IsEnabled="{Binding IsActive}" />
                 </Grid>
-                
+
                 <Label Text="Orientation Sensor" FontAttributes="Bold" Margin="0,6,0,0" />
                 <Grid x:Name="GridOrientation">
                     <Grid.BindingContext>
@@ -176,6 +176,29 @@
                     <Button Grid.Row="5" Grid.Column="1" Text="Stop" Command="{Binding StopCommand}"
                             IsEnabled="{Binding IsActive}" />
                 </Grid>
+                <Label Text="Monitor barometer for changes." FontAttributes="Bold" Margin="12" />
+                <Grid  x:Name="GridBarometer">
+                    <Grid.BindingContext>
+                        <viewmodels:BarometerViewModel />
+                    </Grid.BindingContext>
+                    <Grid.RowDefinitions>
+                        <RowDefinition Height="Auto" />
+                        <RowDefinition Height="Auto" />
+                    </Grid.RowDefinitions>
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="*" />
+                        <ColumnDefinition Width="*" />
+                    </Grid.ColumnDefinitions>
+
+                    <Label Grid.Row="0" Grid.ColumnSpan="2"
+                       Text="{Binding BaromterValue, StringFormat='Barometer pressure (hPA): {0:N}'}" />
+
+                    <Button Grid.Row="1" Grid.Column="0" Text="Start" Command="{Binding StartBarometerComand}"
+                        IsEnabled="{Binding BarometerIsActive, Converter={StaticResource NegativeConverter}}" />
+
+                    <Button Grid.Row="1"  Grid.Column="1" Text="Stop" Command="{Binding StopBarometerCommand}"
+                        IsEnabled="{Binding BarometerIsActive}" />
+                </Grid>
             </StackLayout>
         </ScrollView>
     </StackLayout>

Samples/Samples/View/AllSensorsPage.xaml.cs

@@ -20,6 +20,7 @@ protected override void OnAppearing()
             SetupBinding(GridGyro.BindingContext);
             SetupBinding(GridMagnetometer.BindingContext);
             SetupBinding(GridOrientation.BindingContext);
+            SetupBinding(GridBarometer.BindingContext);
         }
 
         protected override void OnDisappearing()
@@ -29,7 +30,7 @@ protected override void OnDisappearing()
             TearDownBinding(GridGyro.BindingContext);
             TearDownBinding(GridMagnetometer.BindingContext);
             TearDownBinding(GridOrientation.BindingContext);
-
+            TearDownBinding(GridBarometer.BindingContext);
             base.OnDisappearing();
         }
     }

Samples/Samples/View/BarometerPage.xaml

@@ -0,0 +1,48 @@
+<views:BasePage xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:views="clr-namespace:Samples.View"
+             xmlns:viewmodels="clr-namespace:Samples.ViewModel"
+             x:Class="Samples.View.BarometerPage"
+             Title="Barometer">
+    <views:BasePage.BindingContext>
+        <viewmodels:BarometerViewModel />
+    </views:BasePage.BindingContext>
+
+    <StackLayout>
+        <Label Text="Monitor barometer for changes." FontAttributes="Bold" Margin="12" />
+
+        <ScrollView>
+            <Grid Padding="12,0,12,12">
+                <Grid.RowDefinitions>
+                    <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
+                </Grid.RowDefinitions>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="*" />
+                    <ColumnDefinition Width="*" />
+                </Grid.ColumnDefinitions>
+
+                <Label Grid.Row="0" Grid.ColumnSpan="2"
+                       Text="{Binding Pressure, StringFormat='Barometer pressure (hPA): {0:N}'}" />
+
+                <Label Grid.Row="1" Grid.ColumnSpan="2" Text="Speed:" />
+
+                <Picker Grid.Row="2" Grid.ColumnSpan="2" HorizontalOptions="FillAndExpand"
+                    ItemsSource="{Binding Speeds}" 
+                    SelectedIndex="{Binding Speed, Mode=TwoWay}"
+                    IsEnabled="{Binding IsActive, Converter={StaticResource NegativeConverter}}"
+                    Margin="0,0,0,10"/>
+
+
+                <Button Grid.Row="3" Grid.Column="0" Text="Start" Command="{Binding StartCommand}"
+                        IsEnabled="{Binding IsActive, Converter={StaticResource NegativeConverter}}" />
+
+                <Button Grid.Row="3"  Grid.Column="1" Text="Stop" Command="{Binding StopCommand}"
+                        IsEnabled="{Binding IsActive}" />
+            </Grid>
+        </ScrollView>
+    </StackLayout>
+
+</views:BasePage>

Samples/Samples/View/BarometerPage.xaml.cs

@@ -0,0 +1,13 @@
+using Xamarin.Forms;
+using Xamarin.Forms.Xaml;
+
+namespace Samples.View
+{
+    public partial class BarometerPage : BasePage
+    {
+        public BarometerPage()
+        {
+            InitializeComponent();
+        }
+    }
+}

Samples/Samples/ViewModel/BarometerViewModel.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Collections.Generic;
+using System.Windows.Input;
+using Xamarin.Essentials;
+using Xamarin.Forms;
+
+namespace Samples.ViewModel
+{
+    public class BarometerViewModel : BaseViewModel
+    {
+        bool isActive;
+        double pressure;
+        int speed = 2;
+
+        public BarometerViewModel()
+        {
+            StartCommand = new Command(OnStartBarometer);
+            StopCommand = new Command(OnStop);
+        }
+
+        public ICommand StartCommand { get; }
+
+        public ICommand StopCommand { get; }
+
+        public bool IsActive
+        {
+            get => isActive;
+            set => SetProperty(ref isActive, value);
+        }
+
+        public double Pressure
+        {
+            get => pressure;
+            set => SetProperty(ref pressure, value);
+        }
+
+        public List<string> Speeds { get; } =
+           new List<string>
+           {
+                        "Fastest",
+                        "Game",
+                        "Normal",
+                        "User Interface"
+           };
+
+        public int Speed
+        {
+            get => speed;
+            set => SetProperty(ref speed, value);
+        }
+
+        public override void OnAppearing()
+        {
+            Barometer.ReadingChanged += OnBarometerReadingChanged;
+            base.OnAppearing();
+        }
+
+        public override void OnDisappearing()
+        {
+            OnStop();
+            Barometer.ReadingChanged -= OnBarometerReadingChanged;
+
+            base.OnDisappearing();
+        }
+
+        async void OnStartBarometer()
+        {
+            try
+            {
+                Barometer.Start((SensorSpeed)Speed);
+                IsActive = true;
+            }
+            catch (Exception ex)
+            {
+                await DisplayAlertAsync($"Unable to start barometer: {ex.Message}");
+            }
+        }
+
+        void OnBarometerReadingChanged(object sender, BarometerChangedEventArgs e)
+        {
+            Pressure = e.Reading.Pressure;
+        }
+
+        void OnStop()
+        {
+            IsActive = false;
+            Barometer.Stop();
+            Barometer.ReadingChanged -= OnBarometerReadingChanged;
+        }
+    }
+}

Samples/Samples/ViewModel/CompassViewModel.cs

@@ -102,9 +102,8 @@ async void OnStartCompass1()
                 if (Compass.IsMonitoring)
                     OnStopCompass2();
 
-                Compass.ReadingChanged += OnCompass1ReadingChanged;
-
                 Compass.Start((SensorSpeed)Speed1);
+                Compass.ReadingChanged += OnCompass1ReadingChanged;
                 Compass1IsActive = true;
             }
             catch (Exception ex)
@@ -141,8 +140,8 @@ async void OnStartCompass2()
                 if (Compass.IsMonitoring)
                     OnStopCompass1();
 
-                Compass.ReadingChanged += OnCompass2ReadingChanged;
                 Compass.Start((SensorSpeed)Speed2);
+                Compass.ReadingChanged += OnCompass2ReadingChanged;
                 Compass2IsActive = true;
             }
             catch (Exception ex)

Samples/Samples/ViewModel/HomeViewModel.cs

@@ -28,14 +28,20 @@ public HomeViewModel()
                     "📏",
                     "All Sensors",
                     typeof(AllSensorsPage),
-                    "Have a look at the accelerometer, compass, gyroscope, magnetometer, and orientation sensors.",
-                    new[] { "accelerometer", "compass", "gyroscope", "magnetometer", "orientation", "sensors", "hardware", "device" }),
+                    "Have a look at the accelerometer, barometer, compass, gyroscope, magnetometer, and orientation sensors.",
+                    new[] { "accelerometer", "barometer", "compass", "gyroscope", "magnetometer", "orientation", "sensors", "hardware", "device" }),
                 new SampleItem(
                     "📦",
                     "App Info",
                     typeof(AppInfoPage),
                     "Find out about the app with ease.",
                     new[] { "app", "info" }),
+                new SampleItem(
+                    "📏",
+                    "Barometer",
+                    typeof(BarometerPage),
+                    "Easily detect pressure level, via the device barometer.",
+                    new[] { "barometer", "hardware", "device", "sensor" }),
                 new SampleItem(
                     "🔋",
                     "Battery",