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Add MonochromeFile support for Android adaptive icons #34569

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8cc937d
Add MonochromeFile support for Android adaptive icons (#22543)
jfversluis Mar 19, 2026
c0fe91e
Only write adaptive icon XML when content changes
jfversluis Mar 19, 2026
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76 changes: 65 additions & 11 deletions src/SingleProject/Resizetizer/src/AndroidAdaptiveIconGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,16 @@ public AndroidAdaptiveIconGenerator(ResizeImageInfo info, string appIconName, st
<monochrome android:drawable=""@mipmap/{name}_foreground"" />
</adaptive-icon>";

const string AdaptiveIconDrawableWithMonochromeXml =
@"<?xml version=""1.0"" encoding=""utf-8""?>
<adaptive-icon xmlns:android=""http://schemas.android.com/apk/res/android"">
<background android:drawable=""@mipmap/{name}_background""/>
<foreground android:drawable=""@mipmap/{name}_foreground""/>
<monochrome android:drawable=""@mipmap/{name}_monochrome"" />
</adaptive-icon>";

bool HasMonochromeFile => !string.IsNullOrEmpty(Info.MonochromeFilename);

public IEnumerable<ResizedImageInfo> Generate()
{
var sw = new Stopwatch();
Expand All @@ -42,6 +52,8 @@ public IEnumerable<ResizedImageInfo> Generate()

ProcessBackground(results, fullIntermediateOutputPath);
ProcessForeground(results, fullIntermediateOutputPath);
if (HasMonochromeFile)
ProcessMonochrome(results, fullIntermediateOutputPath);
ProcessAdaptiveIcon(results, fullIntermediateOutputPath);

sw.Stop();
Expand Down Expand Up @@ -138,29 +150,71 @@ void ProcessForeground(List<ResizedImageInfo> results, DirectoryInfo fullInterme
}
}

void ProcessMonochrome(List<ResizedImageInfo> results, DirectoryInfo fullIntermediateOutputPath)
{
var monochromeFile = Info.MonochromeFilename;
var (monochromeExists, monochromeModified) = Utils.FileExists(monochromeFile);
var monochromeDestFilename = AppIconName + "_monochrome.png";

if (monochromeExists)
Logger.Log("Converting Monochrome SVG to PNG: " + monochromeFile);
else
Logger.Log("Monochrome was not found (will manufacture): " + monochromeFile);

foreach (var dpi in DpiPath.Android.AppIconParts)
{
var dir = Path.Combine(fullIntermediateOutputPath.FullName, dpi.Path);
var destination = Path.Combine(dir, monochromeDestFilename);
var (destinationExists, destinationModified) = Utils.FileExists(destination);
Directory.CreateDirectory(dir);

if (destinationModified > monochromeModified)
{
Logger.Log($"Skipping `{monochromeFile}` => `{destination}` file is up to date.");
results.Add(new ResizedImageInfo { Dpi = dpi, Filename = destination });
continue;
}

Logger.Log($"App Icon Monochrome Part: " + destination);

if (monochromeExists)
{
var tools = SkiaSharpTools.Create(Info.MonochromeIsVector, Info.MonochromeFilename, dpi.Size, null, null, Logger);
tools.Resize(dpi, destination, dpiSizeIsAbsolute: true);
}
else
{
var tools = SkiaSharpTools.CreateImaginary(null, Logger);
tools.Resize(dpi, destination);
}

results.Add(new ResizedImageInfo { Dpi = dpi, Filename = destination });
}
}

void ProcessAdaptiveIcon(List<ResizedImageInfo> results, DirectoryInfo fullIntermediateOutputPath)
{
var dir = Path.Combine(fullIntermediateOutputPath.FullName, "mipmap-anydpi-v26");
var adaptiveIconDestination = Path.Combine(dir, AppIconName + ".xml");
var adaptiveIconRoundDestination = Path.Combine(dir, AppIconName + "_round.xml");
Directory.CreateDirectory(dir);

if (File.Exists(adaptiveIconDestination) && File.Exists(adaptiveIconRoundDestination))
{
results.Add(new ResizedImageInfo { Dpi = new DpiPath("mipmap-anydpi-v26", 1), Filename = adaptiveIconDestination });
results.Add(new ResizedImageInfo { Dpi = new DpiPath("mipmap-anydpi-v26", 1, "_round"), Filename = adaptiveIconRoundDestination });
return;
}

var adaptiveIconXmlStr = AdaptiveIconDrawableXml
var adaptiveIconXmlStr = (HasMonochromeFile ? AdaptiveIconDrawableWithMonochromeXml : AdaptiveIconDrawableXml)
.Replace("{name}", AppIconName);

// Write out the adaptive icon xml drawables
File.WriteAllText(adaptiveIconDestination, adaptiveIconXmlStr);
File.WriteAllText(adaptiveIconRoundDestination, adaptiveIconXmlStr);
// Only write when content changed to avoid unnecessary timestamp updates
WriteFileIfChanged(adaptiveIconDestination, adaptiveIconXmlStr);
WriteFileIfChanged(adaptiveIconRoundDestination, adaptiveIconXmlStr);

results.Add(new ResizedImageInfo { Dpi = new DpiPath("mipmap-anydpi-v26", 1), Filename = adaptiveIconDestination });
results.Add(new ResizedImageInfo { Dpi = new DpiPath("mipmap-anydpi-v26", 1, "_round"), Filename = adaptiveIconRoundDestination });
}

static void WriteFileIfChanged(string path, string content)
{
if (File.Exists(path) && File.ReadAllText(path) == content)
return;
File.WriteAllText(path, content);
}
}
}
14 changes: 14 additions & 0 deletions src/SingleProject/Resizetizer/src/ResizeImageInfo.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,10 @@ internal class ResizeImageInfo

public double ForegroundScale { get; set; } = 1.0;

public string? MonochromeFilename { get; set; }

public bool MonochromeIsVector => IsVectorFilename(MonochromeFilename);

private static bool IsVectorFilename(string? filename)
=> IsVectorExtension(Path.GetExtension(filename));

Expand Down Expand Up @@ -124,6 +128,16 @@ public static ResizeImageInfo Parse(ITaskItem image)
info.ForegroundFilename = fgFileInfo.FullName;
}

var monoFile = image.GetMetadata("MonochromeFile");
if (!string.IsNullOrEmpty(monoFile))
{
var monoFileInfo = new FileInfo(monoFile);
if (!monoFileInfo.Exists)
throw new FileNotFoundException("Unable to find monochrome file: " + monoFileInfo.FullName, monoFileInfo.FullName);

info.MonochromeFilename = monoFileInfo.FullName;
}

// make sure the image is a foreground if this is an icon
if (info.IsAppIcon && string.IsNullOrEmpty(info.ForegroundFilename))
{
Expand Down
76 changes: 76 additions & 0 deletions src/SingleProject/Resizetizer/test/UnitTests/ResizetizeImagesTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1029,6 +1029,82 @@ public void NonExistantFilesAreDeleted()

// AssertFileSize(DestinationFilename, exWidth, exHeight);
//}

[Fact]
public void AppIconWithMonochromeFileGeneratesMonochromeLayer()
{
var items = new[]
{
new TaskItem("images/dotnet_background.svg", new Dictionary<string, string>
{
["IsAppIcon"] = bool.TrueString,
["ForegroundFile"] = "images/appicon.svg",
["MonochromeFile"] = "images/camera.svg",
}),
};

var task = GetNewTask(items);
var success = task.Execute();
Assert.True(success, LogErrorEvents.FirstOrDefault()?.Message);

// Monochrome PNG should be generated at each density
AssertFileExists("mipmap-mdpi/dotnet_background_monochrome.png");
AssertFileExists("mipmap-xhdpi/dotnet_background_monochrome.png");

// Adaptive icon XML should reference the monochrome layer
AssertFileContains("mipmap-anydpi-v26/dotnet_background.xml",
"<monochrome android:drawable=\"@mipmap/dotnet_background_monochrome\"");
AssertFileContains("mipmap-anydpi-v26/dotnet_background_round.xml",
"<monochrome android:drawable=\"@mipmap/dotnet_background_monochrome\"");
}

[Fact]
public void AppIconWithoutMonochromeFileFallsBackToForeground()
{
var items = new[]
{
new TaskItem("images/dotnet_background.svg", new Dictionary<string, string>
{
["IsAppIcon"] = bool.TrueString,
["ForegroundFile"] = "images/appicon.svg",
}),
};

var task = GetNewTask(items);
var success = task.Execute();
Assert.True(success, LogErrorEvents.FirstOrDefault()?.Message);

// No monochrome PNG should be generated
AssertFileNotExists("mipmap-mdpi/dotnet_background_monochrome.png");

// Adaptive icon XML should reference the foreground as monochrome (backwards compat)
AssertFileContains("mipmap-anydpi-v26/dotnet_background.xml",
"<monochrome android:drawable=\"@mipmap/dotnet_background_foreground\"");
AssertFileContains("mipmap-anydpi-v26/dotnet_background_round.xml",
"<monochrome android:drawable=\"@mipmap/dotnet_background_foreground\"");
}

[Fact]
public void AppIconMonochromeLayerHasCorrectSize()
{
var items = new[]
{
new TaskItem("images/dotnet_background.svg", new Dictionary<string, string>
{
["IsAppIcon"] = bool.TrueString,
["ForegroundFile"] = "images/appicon.svg",
["MonochromeFile"] = "images/camera.svg",
}),
};

var task = GetNewTask(items);
var success = task.Execute();
Assert.True(success, LogErrorEvents.FirstOrDefault()?.Message);

// Monochrome follows the same AppIconParts sizing as foreground/background
AssertFileSize("mipmap-mdpi/dotnet_background_monochrome.png", 108, 108);
AssertFileSize("mipmap-xhdpi/dotnet_background_monochrome.png", 216, 216);
}
}

public class ExecuteForiOS : ExecuteForPlatformApp
Expand Down
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