Wpf High Dpi Analyzer

wpf-high-dpi-analyzer

Analyze and fix WPF applications for high DPI support. This skill identifies DPI-related issues and provides fixes for per-monitor DPI awareness, bitmap scaling, and layout problems on high-resolution displays.

Capabilities

• Detect DPI awareness configuration issues
• Find hardcoded pixel values
• Identify bitmap scaling problems
• Check for per-monitor DPI support
• Analyze transform and layout issues
• Review app.manifest DPI settings
• Generate fixes for common DPI problems
• Test multi-monitor DPI scenarios

Input Schema

{
  "type": "object",
  "properties": {
    "projectPath": {
      "type": "string",
      "description": "Path to the WPF project"
    },
    "targetDpiMode": {
      "enum": ["system", "per-monitor", "per-monitor-v2"],
      "default": "per-monitor-v2"
    },
    "checkCategories": {
      "type": "array",
      "items": {
        "enum": ["manifest", "hardcoded-pixels", "bitmaps", "layouts", "transforms", "fonts"]
      },
      "default": ["manifest", "hardcoded-pixels", "bitmaps", "layouts"]
    },
    "generateFixes": {
      "type": "boolean",
      "default": true
    }
  },
  "required": ["projectPath"]
}

Output Schema

{
  "type": "object",
  "properties": {
    "success": { "type": "boolean" },
    "dpiMode": { "type": "string" },
    "issues": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "severity": { "enum": ["critical", "high", "medium", "low"] },
          "category": { "type": "string" },
          "file": { "type": "string" },
          "line": { "type": "number" },
          "description": { "type": "string" },
          "fix": { "type": "string" }
        }
      }
    },
    "recommendations": {
      "type": "array",
      "items": { "type": "string" }
    }
  },
  "required": ["success", "issues"]
}

DPI Awareness Modes

System DPI Aware (Legacy)

<!-- app.manifest -->
<application xmlns="urn:schemas-microsoft-com:asm.v3">
  <windowsSettings>
    <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>
  </windowsSettings>
</application>

Per-Monitor DPI Aware (Windows 8.1+)

<application xmlns="urn:schemas-microsoft-com:asm.v3">
  <windowsSettings>
    <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/PM</dpiAware>
  </windowsSettings>
</application>

Per-Monitor V2 DPI Aware (Windows 10 1703+)

<application xmlns="urn:schemas-microsoft-com:asm.v3">
  <windowsSettings>
    <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/PM</dpiAware>
    <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
  </windowsSettings>
</application>

Common Issues and Fixes

Hardcoded Pixel Values

<!-- BAD: Hardcoded pixels -->
<Button Width="100" Height="30"/>
<Grid Margin="10,5,10,5"/>
<TextBlock FontSize="12"/>

<!-- GOOD: Use device-independent units or relative sizing -->
<Button MinWidth="80" MinHeight="24" Padding="16,4"/>
<Grid Margin="{StaticResource StandardMargin}"/>
<TextBlock Style="{StaticResource BodyTextStyle}"/>

Bitmap Images

<!-- BAD: Single resolution bitmap -->
<Image Source="icon.png"/>

<!-- GOOD: Use vector or provide multiple resolutions -->
<Image>
  <Image.Source>
    <DrawingImage>
      <!-- Vector drawing -->
    </DrawingImage>
  </Image.Source>
</Image>

<!-- Or use BitmapScalingMode for crisp scaling -->
<Image Source="icon.png"
       RenderOptions.BitmapScalingMode="HighQuality"/>

Dynamic DPI Handling

// Handle DPI changes at runtime
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        // Get current DPI
        var dpiScale = VisualTreeHelper.GetDpi(this);
        Debug.WriteLine($"DPI: {dpiScale.PixelsPerDip * 96}");
    }

    protected override void OnDpiChanged(DpiScale oldDpi, DpiScale newDpi)
    {
        base.OnDpiChanged(oldDpi, newDpi);

        // Handle DPI change
        Debug.WriteLine($"DPI changed from {oldDpi.PixelsPerDip * 96} to {newDpi.PixelsPerDip * 96}");

        // Reload high-DPI assets if needed
        ReloadAssets(newDpi);
    }

    private void ReloadAssets(DpiScale dpi)
    {
        // Load appropriate resolution assets
        var scale = dpi.PixelsPerDip;
        string suffix = scale >= 2 ? "@2x" : scale >= 1.5 ? "@1.5x" : "";
        // Load assets with suffix
    }
}

Per-Monitor V2 Setup

// App.xaml.cs
public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs e)
    {
        // Enable Per-Monitor V2 DPI awareness (Windows 10 1703+)
        if (Environment.OSVersion.Version >= new Version(10, 0, 15063))
        {
            // Per-Monitor V2 is automatic with manifest, but verify
            var awareness = GetProcessDpiAwareness();
            Debug.WriteLine($"DPI Awareness: {awareness}");
        }

        base.OnStartup(e);
    }

    [DllImport("shcore.dll")]
    private static extern int GetProcessDpiAwareness(IntPtr hprocess, out int awareness);

    private static int GetProcessDpiAwareness()
    {
        GetProcessDpiAwareness(IntPtr.Zero, out int awareness);
        return awareness;
    }
}

Transform Issues

// BAD: Manual scaling calculations
var scale = 96.0 / GetSystemDpi();
transform.ScaleX = scale;
transform.ScaleY = scale;

// GOOD: Let WPF handle scaling
// Use device-independent units, WPF handles the rest
<Canvas>
    <Rectangle Canvas.Left="10" Canvas.Top="10"
               Width="100" Height="50"/>
</Canvas>

Font Scaling

<!-- BAD: Hardcoded font size -->
<TextBlock FontSize="14"/>

<!-- GOOD: Use named styles or relative sizing -->
<TextBlock Style="{DynamicResource MaterialDesignBody1TextBlock}"/>

<!-- Or use system font size -->
<TextBlock FontSize="{x:Static SystemFonts.MessageFontSize}"/>

Project Configuration

<!-- .csproj -->
<PropertyGroup>
  <TargetFramework>net8.0-windows</TargetFramework>
  <UseWPF>true</UseWPF>

  <!-- Enable high DPI support -->
  <ApplicationHighDpiMode>PerMonitorV2</ApplicationHighDpiMode>
</PropertyGroup>

<!-- Include app.manifest -->
<ItemGroup>
  <None Update="app.manifest">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </None>
</ItemGroup>

Testing Multi-DPI

# Change display scaling via PowerShell (requires restart)
Set-ItemProperty -Path "HKCU:\Control Panel\Desktop" -Name "LogPixels" -Value 144  # 150%

# Test with multiple monitors at different DPIs
# Use Windows display settings to set different scales per monitor

Best Practices

1. Use Per-Monitor V2: Best scaling support on Windows 10+
2. Avoid hardcoded pixels: Use relative or auto sizing
3. Use vector graphics: SVG or DrawingImage for icons
4. Provide multi-resolution bitmaps: @1x, @1.5x, @2x
5. Handle OnDpiChanged: Reload assets when DPI changes
6. Test at multiple DPI levels: 100%, 125%, 150%, 200%

Related Skills

• wpf-xaml-style-generator - DPI-aware styles
• desktop-accessibility process - Accessibility testing
• visual-regression-setup - Visual testing at different DPIs

Related Agents

• wpf-dotnet-expert - WPF expertise
• desktop-ux-analyst - UX review