Json safe float/power control hub app start

PowerControlHub.sln

@@ -45,6 +45,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		README.md = README.md
 	EndProjectSection
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "PowerControlHubApp", "PowerControlHubApp\PowerControlHubApp.csproj", "{9A5A950B-B42B-40DE-BDA7-299184BB23BA}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -85,6 +87,18 @@ Global
 		{31F2CD6A-B9E7-9FD4-3808-399C52A59619}.Release|ARM.Build.0 = Release|Any CPU
 		{31F2CD6A-B9E7-9FD4-3808-399C52A59619}.Release|ARM64.ActiveCfg = Release|Any CPU
 		{31F2CD6A-B9E7-9FD4-3808-399C52A59619}.Release|ARM64.Build.0 = Release|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Debug|ARM.Build.0 = Debug|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Debug|ARM64.ActiveCfg = Debug|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Debug|ARM64.Build.0 = Debug|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Release|ARM.ActiveCfg = Release|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Release|ARM.Build.0 = Release|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Release|ARM64.ActiveCfg = Release|Any CPU
+		{9A5A950B-B42B-40DE-BDA7-299184BB23BA}.Release|ARM64.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

PowerControlHub/Dht11SensorHandler.h

@@ -250,24 +250,24 @@ class Dht11SensorHandler : public BaseSensor, public BroadcastLoggerSupport
 
 	void formatStatusJson(char* buffer, size_t size) override
 	{
-        // Validate output buffer
+		// Validate output buffer
 		if (!buffer || size == 0)
 		{
 			return;
 		}
 
-		char celsius[8];
-		char humidity[8];
-		char celsiusOffset[8];
-		char humidityOffset[8];
-		dtostrf(_celsius, 1, 1, celsius);
-		dtostrf(_humidity, 1, 1, humidity);
-		dtostrf(_temperatureOffset, 1, 1, celsiusOffset);
-		dtostrf(_humidityOffset, 1, 1, humidityOffset);
+		char celsius[16];
+		char humidity[16];
+		char celsiusOffset[16];
+		char humidityOffset[16];
+		SystemFunctions::safeJsonFloat(_celsius, celsius, sizeof(celsius), 1);
+		SystemFunctions::safeJsonFloat(_humidity, humidity, sizeof(humidity), 1);
+		SystemFunctions::safeJsonFloat(_temperatureOffset, celsiusOffset, sizeof(celsiusOffset), 1);
+		SystemFunctions::safeJsonFloat(_humidityOffset, humidityOffset,sizeof(humidityOffset), 1);
 
 		double dewPt = Environment::dewPoint(_celsius, _humidity);
-		char dewPointStr[8];
-		dtostrf(dewPt, 1, 1, dewPointStr);
+		char dewPointStr[16];
+		SystemFunctions::safeJsonFloat(static_cast<float>(dewPt), dewPointStr, sizeof(dewPointStr), 1);
 
 		char comfortBuf[24];
 		strncpy_P(comfortBuf, Environment::getComfortDescription(_celsius, _humidity, dewPt), sizeof(comfortBuf));

PowerControlHub/GpsSensorHandler.h

@@ -28,6 +28,7 @@
 #include "BaseSensor.h"
 #include "DateTimeManager.h"
 #include "SensorCommandHandler.h"
+#include "SystemFunctions.h"
 
 constexpr unsigned long GpsCheckMs = 10;
 constexpr unsigned long StatusUpdateMs = 1000UL;
@@ -422,17 +423,17 @@ class GpsSensorHandler : public BaseSensor, public BroadcastLoggerSupport
 	{
 		char lat[16];
 		char lon[16];
-		char alt[12];
-		char speed[12];
-		char course[12];
-		
-		dtostrf(_latitude, 1, 6, lat);
-		dtostrf(_longitude, 1, 6, lon);
-		dtostrf(_altitude, 1, 2, alt);
-		dtostrf(_speedKmh, 1, 2, speed);
-		dtostrf(_courseDeg, 1, 2, course);
-
-		snprintf_P(buffer, size, 
+		char alt[16];
+		char speed[16];
+		char course[16];
+
+		SystemFunctions::safeJsonFloat(static_cast<float>(_latitude),  lat,    sizeof(lat),    6);
+		SystemFunctions::safeJsonFloat(static_cast<float>(_longitude), lon,    sizeof(lon),    6);
+		SystemFunctions::safeJsonFloat(static_cast<float>(_altitude),  alt,    sizeof(alt),    2);
+		SystemFunctions::safeJsonFloat(static_cast<float>(_speedKmh),  speed,  sizeof(speed),  2);
+		SystemFunctions::safeJsonFloat(static_cast<float>(_courseDeg), course, sizeof(course), 2);
+
+		snprintf_P(buffer, size,
 			PSTR("\"gps\":{\"lat\":%s,\"lon\":%s,\"alt\":%s,\"speed\":%s,\"course\":%s,\"sats\":%lu,\"valid\":%s}"),
 			lat, lon, alt, speed, course, _satellites, _hasValidFix ? "true" : "false");
 	}

PowerControlHub/SystemFunctions.cpp

@@ -607,4 +607,19 @@ void SystemFunctions::formatTimeParts(char* buffer, size_t bufferSize, const Tim
         (unsigned)timeparts.hours,
         (unsigned)timeparts.minutes,
         (unsigned)timeparts.seconds);
+}
+
+void SystemFunctions::safeJsonFloat(float value, char* output, size_t outputSize, uint8_t decimals)
+{
+    if (!output || outputSize == 0)
+        return;
+
+    if (isnan(value) || isinf(value))
+    {
+        strncpy(output, "null", outputSize);
+        output[outputSize - 1] = '\0';
+        return;
+    }
+
+    dtostrf(value, 1, decimals, output);
 }

PowerControlHub/SystemFunctions.h

@@ -353,6 +353,20 @@ class SystemFunctions
      */
     static void sanitizeJsonString(const char* input, char* output, size_t outputSize);
 
+    /**
+     * @brief Format a float as a JSON number, emitting null for non-finite values.
+     *
+     * IEEE 754 special values (NaN, +Inf, -Inf) are not valid JSON numbers.
+     * This helper emits the literal `null` for any non-finite value so that
+     * the output is always valid JSON.
+     *
+     * @param value      The float value to format.
+     * @param output     Destination buffer.
+     * @param outputSize Size of destination buffer including null terminator.
+     * @param decimals   Number of decimal places (passed to dtostrf).
+     */
+    static void safeJsonFloat(float value, char* output, size_t outputSize, uint8_t decimals = 2);
+
     /**
      * @brief Escape a string for safe embedding in HTML content.
      *

PowerControlHubApp/App.xaml

@@ -0,0 +1,15 @@
+<?xml version = "1.0" encoding = "UTF-8" ?>
+<Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:PowerControlHubApp"
+             x:Class="PowerControlHubApp.App">
+    <Application.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="Resources/Styles/Colors.xaml" />
+                <ResourceDictionary Source="Resources/Styles/AppColorsLight.xaml" />
+                <ResourceDictionary Source="Resources/Styles/Styles.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Application.Resources>
+</Application>

PowerControlHubApp/App.xaml.cs

@@ -0,0 +1,66 @@
+using Microsoft.Extensions.DependencyInjection;
+using PowerControlHubApp.Services;
+
+namespace PowerControlHubApp
+{
+    public partial class App : Application
+    {
+        public App(ThemeService themeService)
+        {
+            InitializeComponent();
+            // Apply after InitializeComponent so Application.Resources is populated.
+            themeService.ApplySaved();
+        }
+
+        protected override Window CreateWindow(IActivationState? activationState)
+        {
+            var window = new Window(new AppShell());
+
+#if WINDOWS
+            window.HandlerChanged += OnWindowHandlerChanged;
+#endif
+
+            return window;
+        }
+
+#if WINDOWS
+        private static void OnWindowHandlerChanged(object? sender, EventArgs e)
+        {
+            if (sender is not Window mauiWindow)
+                return;
+
+            // Detach — only needs to run once
+            mauiWindow.HandlerChanged -= OnWindowHandlerChanged;
+
+            if (mauiWindow.Handler?.PlatformView is not Microsoft.UI.Xaml.Window nativeWindow)
+                return;
+
+            var appWindow = nativeWindow.AppWindow;
+
+            // Restore saved position and size (stored in physical pixels)
+            int savedW = Preferences.Get("win_w", 0);
+            int savedH = Preferences.Get("win_h", 0);
+            int savedX = Preferences.Get("win_x", int.MinValue);
+            int savedY = Preferences.Get("win_y", int.MinValue);
+
+            if (savedW > 0 && savedH > 0)
+                appWindow.Resize(new Windows.Graphics.SizeInt32(savedW, savedH));
+
+            if (savedX != int.MinValue && savedY != int.MinValue)
+                appWindow.Move(new Windows.Graphics.PointInt32(savedX, savedY));
+
+            // Persist position/size whenever the window moves or is resized
+            appWindow.Changed += (aw, args) =>
+            {
+                if (!args.DidPositionChange && !args.DidSizeChange)
+                    return;
+
+                Preferences.Set("win_x", aw.Position.X);
+                Preferences.Set("win_y", aw.Position.Y);
+                Preferences.Set("win_w", aw.Size.Width);
+                Preferences.Set("win_h", aw.Size.Height);
+            };
+        }
+#endif
+    }
+}

PowerControlHubApp/AppShell.xaml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<Shell
+    x:Class="PowerControlHubApp.AppShell"
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:views="clr-namespace:PowerControlHubApp.Views"
+    Title="PowerControlHub"
+    Shell.NavBarIsVisible="False">
+
+    <ShellContent
+        x:Name="DashboardPage"
+        Title="Dashboard"
+        Route="DashboardPage"
+        ContentTemplate="{DataTemplate views:DashboardPage}" />
+
+    <ShellContent
+        x:Name="SettingsPage"
+        Title="Settings"
+        Route="SettingsPage"
+        ContentTemplate="{DataTemplate views:SettingsPage}" />
+
+</Shell>

PowerControlHubApp/AppShell.xaml.cs

@@ -0,0 +1,10 @@
+namespace PowerControlHubApp
+{
+    public partial class AppShell : Shell
+    {
+        public AppShell()
+        {
+            InitializeComponent();
+        }
+    }
+}

PowerControlHubApp/Converters/ValueConverters.cs

@@ -0,0 +1,43 @@
+using System.Globalization;
+
+namespace PowerControlHubApp.Converters;
+
+/// <summary>Returns true when the integer value is greater than zero.</summary>
+public class IntToBoolConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => value is int i && i > 0;
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}
+
+/// <summary>Returns true when the integer value equals zero (inverse of IntToBoolConverter).</summary>
+public class IntToInverseBoolConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => value is not int i || i == 0;
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}
+
+/// <summary>Returns true when the string is non-empty.</summary>
+public class StringToBoolConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => value is string s && !string.IsNullOrEmpty(s);
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}
+
+/// <summary>Returns a green colour for true (connected) and a red colour for false (disconnected).</summary>
+public class BoolToStatusColorConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => value is true ? Color.FromArgb("#44cc44") : Color.FromArgb("#cc4444");
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}

PowerControlHubApp/MainPage.xaml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="PowerControlHubApp.MainPage">
+
+    <ScrollView>
+        <VerticalStackLayout
+            Padding="30,0"
+            Spacing="25">
+            <Image
+                Source="dotnet_bot.png"
+                HeightRequest="185"
+                Aspect="AspectFit"
+                SemanticProperties.Description="dot net bot in a submarine number ten" />
+
+            <Label
+                Text="Hello, World!"
+                Style="{StaticResource Headline}"
+                SemanticProperties.HeadingLevel="Level1" />
+
+            <Label
+                Text="Welcome to &#10;.NET Multi-platform App UI"
+                Style="{StaticResource SubHeadline}"
+                SemanticProperties.HeadingLevel="Level2"
+                SemanticProperties.Description="Welcome to dot net Multi platform App U I" />
+
+            <Button
+                x:Name="CounterBtn"
+                Text="Click me" 
+                SemanticProperties.Hint="Counts the number of times you click"
+                Clicked="OnCounterClicked"
+                HorizontalOptions="Fill" />
+        </VerticalStackLayout>
+    </ScrollView>
+
+</ContentPage>

PowerControlHubApp/MainPage.xaml.cs

@@ -0,0 +1,24 @@
+namespace PowerControlHubApp
+{
+    public partial class MainPage : ContentPage
+    {
+        int count = 0;
+
+        public MainPage()
+        {
+            InitializeComponent();
+        }
+
+        private void OnCounterClicked(object? sender, EventArgs e)
+        {
+            count++;
+
+            if (count == 1)
+                CounterBtn.Text = $"Clicked {count} time";
+            else
+                CounterBtn.Text = $"Clicked {count} times";
+
+            SemanticScreenReader.Announce(CounterBtn.Text);
+        }
+    }
+}