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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 background color into a HDC. Restores the original background color 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>
internal readonly ref struct SetBackgroundColorScope
{
private readonly COLORREF _previousColor;
private readonly HDC _hdc;
/// <summary>
/// Sets text color <paramref name="color"/> in the given <paramref name="hdc"/> using
/// <see cref="PInvokeCore.SetBkColor(HDC, COLORREF)"/>.
/// </summary>
public SetBackgroundColorScope(HDC hdc, COLORREF color)
{
_previousColor = PInvokeCore.SetBkColor(hdc, color);
// If we didn't actually change the color, don't keep the HDC so we skip putting back the same state.
_hdc = color == _previousColor ? default : hdc;
}
public void Dispose()
{
if (!_hdc.IsNull)
{
PInvokeCore.SetBkColor(_hdc, _previousColor);
}
}
}
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