[xabt] pass in $(SupportedOSPlatformVersion) to <Aapt2Link/>

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Aapt2.targets

@@ -166,6 +166,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
       JavaPlatformJarPath="$(JavaPlatformJarPath)"
       JavaDesignerOutputDirectory="$(ResgenTemporaryDirectory)"
       CompiledResourceFlatFiles="@(_CompiledFlatFiles)"
+      SupportedOSPlatformVersion="$(SupportedOSPlatformVersion)"
       AndroidManifestFile="$(_AndroidManifestAbs)"
       ManifestFiles="$(ResgenTemporaryDirectory)\AndroidManifest.xml"
       AdditionalAndroidResourcePaths="@(_LibraryResourceDirectories)"
@@ -213,6 +214,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
   </PropertyGroup>
   <MakeDir Directories="$(_OutputFileDir)" Condition=" !Exists ('$(_OutputFileDir)') " />
   <Aapt2Link
+      SupportedOSPlatformVersion="$(SupportedOSPlatformVersion)"
       AndroidManifestFile="$(_AndroidManifestAbs)"
       CompiledResourceFlatFiles="@(_CompiledFlatFiles)"
       DaemonMaxInstanceCount="$(Aapt2DaemonMaxInstanceCount)"

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2.cs

@@ -36,7 +36,9 @@ public abstract class Aapt2 : AsyncTask {
 
 		public ITaskItem []? ResourceDirectories { get; set; }
 
-		public ITaskItem? AndroidManifestFile { get; set;}
+		public ITaskItem? AndroidManifestFile { get; set; }
+
+		public string? SupportedOSPlatformVersion { get; set; }
 
 		public string? ResourceSymbolsTextFile { get; set; }
 

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2Link.cs

@@ -2,13 +2,10 @@
 #nullable enable
 
 using System;
-using System.Diagnostics;
 using System.IO;
+using System.Globalization;
 using System.Linq;
 using System.Text;
-using System.Threading;
-using System.Xml;
-using System.Xml.Linq;
 using Microsoft.Build.Utilities;
 using Microsoft.Build.Framework;
 using System.Text.RegularExpressions;
@@ -322,13 +319,21 @@ string [] GenerateCommandLineCommands (string ManifestFile, string? currentAbi,
 			cmd.Add (GetFullPath (currentResourceOutputFile));
 
 			// Add min SDK version from AndroidManifestFile if available
+			string? minSdkVersion = null;
 			if (AndroidManifestFile is { ItemSpec.Length: > 0 }) {
 				var doc = AndroidAppManifest.Load (AndroidManifestFile.ItemSpec, MonoAndroidHelper.SupportedVersions);
 				if (doc.MinSdkVersion.HasValue) {
-					cmd.Add ("--min-sdk-version");
-					cmd.Add (doc.MinSdkVersion.Value.ToString ());
+					minSdkVersion = doc.MinSdkVersion.Value.ToString (CultureInfo.InvariantCulture);
 				}
 			}
+			// Use $(SupportedOSPlatformVersion) if minSdkVersion was not found in the manifest
+			if (minSdkVersion.IsNullOrEmpty () && MonoAndroidHelper.TryParseApiLevel (SupportedOSPlatformVersion, out Version version)) {
+				minSdkVersion = version.Major.ToString (CultureInfo.InvariantCulture);
+			}
+			if (!minSdkVersion.IsNullOrEmpty ()) {
+				cmd.Add ("--min-sdk-version");
+				cmd.Add (minSdkVersion);
+			}
 
 			return cmd.ToArray ();
 		}

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/AndroidResourceTests.cs

@@ -5,7 +5,6 @@
 using System.IO;
 using System.Linq;
 using Microsoft.Build.Framework;
-using System.Text;
 using Xamarin.Android.Tasks;
 using Microsoft.Build.Utilities;
 
@@ -162,6 +161,22 @@ public void AdaptiveIcon ()
 			var proj = new XamarinAndroidApplicationProject {
 				SupportedOSPlatformVersion = "26",
 				AndroidResources = {
+					new AndroidItem.AndroidResource ("Resources\\values\\colors.xml") {
+						TextContent = () => """
+							<resources>
+								<color name="adaptive_icon_background">#2C3E50</color>
+								<color name="adaptive_icon_foreground">#FFFFFF</color>
+							</resources>
+						""",
+					},
+					new AndroidItem.AndroidResource ("Resources\\drawable\\ic_shortcut_add.xml") {
+						TextContent = () => """
+							<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+								<background android:drawable="@color/adaptive_icon_background"/>
+								<foreground android:drawable="@color/adaptive_icon_foreground"/>
+							</adaptive-icon>
+						""",
+					},
 					new AndroidItem.AndroidResource ("Resources\\mipmap-anydpi-v26\\adaptiveicon.xml") {
 						TextContent = () => """
 							<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">

src/Xamarin.Android.Build.Tasks/Utilities/MonoAndroidHelper.cs

@@ -595,6 +595,20 @@ public static int ConvertSupportedOSPlatformVersionToApiLevel (string version)
 			return apiLevel;
 		}
 
+		public static bool TryParseApiLevel (string apiLevel, out Version version)
+		{
+			if (Version.TryParse (apiLevel, out var v)) {
+				version = v;
+				return true;
+			}
+			if (int.TryParse (apiLevel, out var major)) {
+				version = new Version (major, 0);
+				return true;
+			}
+			version = null;
+			return false;
+		}
+
 #if MSBUILD
 		public static string GetAssemblyAbi (ITaskItem asmItem)
 		{