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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
namespace Windows.Win32.Graphics.Gdi;
/// <summary>
/// Helper to scope selecting a given foreground mix mode into a HDC. Restores the original mix mode into the
/// HDC when disposed.
/// </summary>
/// <remarks>
/// <para>
/// Use in a <see langword="using" /> statement. If you must pass this around, always pass by
/// <see langword="ref" /> to avoid duplicating the handle and resetting multiple times.
/// </para>
/// </remarks>
#if DEBUG
internal class SetRop2Scope : DisposalTracking.Tracker, IDisposable
#else
internal readonly ref struct SetRop2Scope
#endif
{
private readonly R2_MODE _previousRop;
private readonly HDC _hdc;
/// <summary>
/// Selects <paramref name="rop2"/> into the given <paramref name="hdc"/> using <see cref="PInvokeCore.SetROP2(HDC, R2_MODE)"/>.
/// </summary>
public SetRop2Scope(HDC hdc, R2_MODE rop2)
{
_previousRop = (R2_MODE)PInvokeCore.SetROP2(hdc, rop2);
// If we didn't actually change the ROP, don't keep the HDC so we skip putting back the same state.
_hdc = _previousRop == rop2 ? default : hdc;
}
public void Dispose()
{
if (!_hdc.IsNull)
{
PInvokeCore.SetROP2(_hdc, _previousRop);
}
#if DEBUG
GC.SuppressFinalize(this);
#endif
}
}
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