CPF/CPF.Mac/Mac/QuickLook/QLThumbnailImage.cs

using CPF.Mac.CoreFoundation;
using CPF.Mac.CoreGraphics;
using CPF.Mac.Foundation;
using CPF.Mac.ObjCRuntime;
using System;
using System.Runtime.InteropServices;

namespace CPF.Mac.QuickLook
{
	public static class QLThumbnailImage
	{
		private static NSString _OptionScaleFactorKey;

		private static NSString _OptionIconModeKey;

		[Field("kQLThumbnailOptionScaleFactorKey", "QuickLook")]
		internal static NSString OptionScaleFactorKey
		{
			get
			{
				if (_OptionScaleFactorKey == null)
				{
					_OptionScaleFactorKey = Dlfcn.GetStringConstant(Libraries.QuickLook.Handle, "kQLThumbnailOptionScaleFactorKey");
				}
				return _OptionScaleFactorKey;
			}
		}

		[Field("kQLThumbnailOptionIconModeKey", "QuickLook")]
		internal static NSString OptionIconModeKey
		{
			get
			{
				if (_OptionIconModeKey == null)
				{
					_OptionIconModeKey = Dlfcn.GetStringConstant(Libraries.QuickLook.Handle, "kQLThumbnailOptionIconModeKey");
				}
				return _OptionIconModeKey;
			}
		}

		[DllImport("/System/Library/Frameworks/QuickLook.framework/QuickLook")]
		private static extern IntPtr QLThumbnailImageCreate(IntPtr allocator, IntPtr url, CGSize maxThumbnailSize, IntPtr options);

		public static CGImage Create(NSUrl url, CGSize maxThumbnailSize, double scaleFactor = 1.0, bool iconMode = false)
		{
			NSMutableDictionary nSMutableDictionary = null;
			if (scaleFactor != 1.0 && iconMode)
			{
				nSMutableDictionary = new NSMutableDictionary();
				nSMutableDictionary.LowlevelSetObject((NSNumber)scaleFactor, OptionScaleFactorKey.Handle);
				nSMutableDictionary.LowlevelSetObject(iconMode ? CFBoolean.True.Handle : CFBoolean.False.Handle, OptionIconModeKey.Handle);
			}
			IntPtr intPtr = QLThumbnailImageCreate(IntPtr.Zero, url.Handle, maxThumbnailSize, nSMutableDictionary?.Handle ?? IntPtr.Zero);
			GC.KeepAlive(nSMutableDictionary);
			if (intPtr != IntPtr.Zero)
			{
				return new CGImage(intPtr, owns: true);
			}
			return null;
		}
	}
}