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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 lifetime of an HDC retrieved via CreateDC/CreateCompatibleDC.
/// Deletes the HDC (if any) 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 risking a double delete.
/// </para>
/// </remarks>
#if DEBUG
internal class CreateDcScope : DisposalTracking.Tracker, IDisposable
#else
internal readonly ref struct CreateDcScope
#endif
{
public HDC HDC { get; }
/// <summary>
/// Creates a compatible HDC for <paramref name="hdc"/> using <see cref="PInvokeCore.CreateCompatibleDC(HDC)"/>.
/// </summary>
/// <remarks>
/// <para>
/// Passing a <see langword="null"/> HDC will use the current screen.
/// </para>
/// </remarks>
public CreateDcScope(HDC hdc)
{
HDC = PInvokeCore.CreateCompatibleDC(hdc);
}
public unsafe CreateDcScope(
string driverName,
string? deviceName = null,
DEVMODEW* lpInitData = default,
bool informationOnly = true)
{
fixed (char* driver = driverName)
fixed (char* device = deviceName)
{
HDC = informationOnly
? PInvokeCore.CreateICW(driver, device, null, lpInitData)
: PInvokeCore.CreateDCW(driver, device, null, lpInitData);
}
}
public static implicit operator HDC(in CreateDcScope scope) => scope.HDC;
public static implicit operator HGDIOBJ(in CreateDcScope scope) => (HGDIOBJ)(scope.HDC.Value);
public static implicit operator nint(in CreateDcScope scope) => scope.HDC;
public static explicit operator WPARAM(in CreateDcScope scope) => (WPARAM)(nuint)(nint)scope.HDC;
public bool IsNull => HDC.IsNull;
public void Dispose()
{
if (!HDC.IsNull)
{
PInvokeCore.DeleteDC(HDC);
}
#if DEBUG
GC.SuppressFinalize(this);
#endif
}
}
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