[ImageResizer] Fix issues with blank Width and Height controls (#37373)

* Allow custom preset's dimensions to be blank in the UI while still persisted as 0.

* XAML formatting - reorder namespaces.

* Add "(auto)" text to zero-value Width/Height in Settings. Ensure Width and Height fields in flyout are formatted to empty when their value is 0.

src/settings-ui/Settings.UI/Converters/ImageResizerDoubleToAutoConverter.cs

@@ -0,0 +1,61 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Globalization;
+using Microsoft.UI.Xaml.Data;
+
+namespace Microsoft.PowerToys.Settings.UI.Converters;
+
+/// <summary>
+/// Converts between double and string for text-based controls bound to Width or Height fields.
+/// Optionally returns localized "Auto" text when the underlying value is 0, letting the UI show,
+/// for example "(auto) x 1024 pixels".
+/// </summary>
+public sealed partial class ImageResizerDoubleToAutoConverter : IValueConverter
+{
+    private static readonly string AutoText =
+        Helpers.ResourceLoaderInstance.ResourceLoader.GetString("ImageResizer_AutoText");
+
+    /// <summary>
+    /// Converts a double to a string, optionally showing "Auto" for 0 values. NaN values are
+    /// converted to empty strings.
+    /// </summary>
+    /// <param name="value">The value to convert from <see cref="double"/> to
+    /// <see cref="string"/>.</param>
+    /// <param name="targetType">The conversion target type. <see cref="string"/> here.</param>
+    /// <param name="parameter">Set to "Auto" to return the localized "Auto" string if the
+    /// value is 0.</param>
+    /// <param name="language">Ignored.</param>
+    /// <returns>The string representation of the passed-in value.</returns>
+    public object Convert(object value, Type targetType, object parameter, string language) =>
+        value switch
+        {
+            double d => d switch
+            {
+                double.NaN => "0",
+                0 => (string)parameter == "Auto" ? AutoText : "0",
+                _ => d.ToString(CultureInfo.CurrentCulture),
+            },
+
+            _ => "0",
+        };
+
+    /// <summary>
+    /// Converts the string representation back to a double, returning 0 if the string is empty,
+    /// null or not a valid number in the specified culture.
+    /// </summary>
+    /// <param name="value">The string value to convert.</param>
+    /// <param name="targetType">The conversion target type. <see cref="double"/> here.</param>
+    /// <param name="parameter">Converter parameter. Unused.</param>
+    /// <param name="language">Ignored.</param>
+    /// <returns>The corresponding double value.</returns>
+    public object ConvertBack(object value, Type targetType, object parameter, string language) =>
+        value switch
+        {
+            null or "" => 0.0,
+            string text when double.TryParse(text, NumberStyles.Any, CultureInfo.CurrentCulture, out double result) => result,
+            _ => 0.0,
+        };
+}

src/settings-ui/Settings.UI/Converters/ImageResizerNumberBoxValueConverter.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using Microsoft.UI.Xaml.Data;
+
+namespace Microsoft.PowerToys.Settings.UI.Converters;
+
+public partial class ImageResizerNumberBoxValueConverter : IValueConverter
+{
+    /// <summary>
+    /// Converts the underlying double value to a display-friendly format. Ensures that NaN values
+    /// are not propagated to the UI.
+    /// </summary>
+    public object Convert(object value, Type targetType, object parameter, string language) =>
+        value is double d && double.IsNaN(d) ? 0.0 : value;
+
+    /// <summary>
+    /// Converts the user input back to the underlying double value. If the input is not a valid
+    /// number, a double with value 0 is returned.
+    /// </summary>
+    public object ConvertBack(object value, Type targetType, object parameter, string language) =>
+        value switch
+        {
+            null => 0.0,
+            double d when double.IsNaN(d) => 0.0,
+            string str when !double.TryParse(str, out _) => 0.0,
+            _ => value,
+        };
+}

src/settings-ui/Settings.UI/Converters/ImageResizerZeroToEmptyStringNumberFormatter.cs

@@ -0,0 +1,39 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Globalization;
+using Microsoft.UI.Xaml.Controls;
+
+namespace Microsoft.PowerToys.Settings.UI.Converters;
+
+public partial class ImageResizerZeroToEmptyStringNumberFormatter
+{
+    public string Format(long value) => throw new NotImplementedException();
+
+    public string Format(ulong value) => throw new NotImplementedException();
+
+    public string Format(double value) => throw new NotImplementedException();
+
+    public string FormatDouble(double? value) => value switch
+    {
+        null => string.Empty,
+        0 => string.Empty,
+        _ => value.Value.ToString(CultureInfo.CurrentCulture),
+    };
+
+    public double? ParseDouble(string text)
+    {
+        if (string.IsNullOrWhiteSpace(text))
+        {
+            return 0.0;
+        }
+
+        return double.TryParse(text, NumberStyles.Any, CultureInfo.CurrentCulture, out double result) ? result : 0.0;
+    }
+
+    public long? ParseInt(string text) => throw new NotImplementedException();
+
+    public ulong? ParseUInt(string text) => throw new NotImplementedException();
+}