localplugin.cs

对gif

		protected virtual bool ValidateProc(ref FreeImageIO io, fi_handle handle) { return false; }
		/// <summary>
		/// Function that can be implemented.
		/// </summary>
		protected virtual string MimeProc() { return ""; }
		/// <summary>
		/// Function that can be implemented.
		/// </summary>
		protected virtual bool SupportsExportBPPProc(int bpp) { return false; }
		/// <summary>
		/// Function that can be implemented.
		/// </summary>
		protected virtual bool SupportsExportTypeProc(FREE_IMAGE_TYPE type) { return false; }
		/// <summary>
		/// Function that can be implemented.
		/// </summary>
		protected virtual bool SupportsICCProfilesProc() { return false; }

		/// <summary>
		/// The constructor automatically registeres the plugin in FreeImage.
		/// To do this it prepares a FreeImage defined structure with function pointers
		/// to the implemented functions or null if not implemented.
		/// Before registing the functions they are pinned in memory so the garbage collector
		/// can't move them around in memory after we passed there addresses to FreeImage.
		/// </summary>
		public LocalPlugin()
		{
			int i = 0;
			implementedMethods = GetImplementedMethods();

			if ((implementedMethods & MethodFlags.DescriptionProc) != 0)
			{
				plugin.descriptionProc = new DescriptionProc(DescriptionProc);
				handles[i++] = GetHandle(plugin.descriptionProc);
			}
			if ((implementedMethods & MethodFlags.ExtensionListProc) != 0)
			{
				plugin.extensionListProc = new ExtensionListProc(ExtensionListProc);
				handles[i++] = GetHandle(plugin.extensionListProc);
			}
			if ((implementedMethods & MethodFlags.RegExprProc) != 0)
			{
				plugin.regExprProc = new RegExprProc(RegExprProc);
				handles[i++] = GetHandle(plugin.regExprProc);
			}
			if ((implementedMethods & MethodFlags.OpenProc) != 0)
			{
				plugin.openProc = new OpenProc(OpenProc);
				handles[i++] = GetHandle(plugin.openProc);
			}
			if ((implementedMethods & MethodFlags.CloseProc) != 0)
			{
				plugin.closeProc = new CloseProc(CloseProc);
				handles[i++] = GetHandle(plugin.closeProc);
			}
			if ((implementedMethods & MethodFlags.PageCountProc) != 0)
			{
				plugin.pageCountProc = new PageCountProc(PageCountProc);
				handles[i++] = GetHandle(plugin.pageCountProc);
			}
			if ((implementedMethods & MethodFlags.PageCapabilityProc) != 0)
			{
				plugin.pageCapabilityProc = new PageCapabilityProc(PageCapabilityProc);
				handles[i++] = GetHandle(plugin.pageCapabilityProc);
			}
			if ((implementedMethods & MethodFlags.LoadProc) != 0)
			{
				plugin.loadProc = new LoadProc(LoadProc);
				handles[i++] = GetHandle(plugin.loadProc);
			}
			if ((implementedMethods & MethodFlags.SaveProc) != 0)
			{
				plugin.saveProc = new SaveProc(SaveProc);
				handles[i++] = GetHandle(plugin.saveProc);
			}
			if ((implementedMethods & MethodFlags.ValidateProc) != 0)
			{
				plugin.validateProc = new ValidateProc(ValidateProc);
				handles[i++] = GetHandle(plugin.validateProc);
			}
			if ((implementedMethods & MethodFlags.MimeProc) != 0)
			{
				plugin.mimeProc = new MimeProc(MimeProc);
				handles[i++] = GetHandle(plugin.mimeProc);
			}
			if ((implementedMethods & MethodFlags.SupportsExportBPPProc) != 0)
			{
				plugin.supportsExportBPPProc = new SupportsExportBPPProc(SupportsExportBPPProc);
				handles[i++] = GetHandle(plugin.supportsExportBPPProc);
			}
			if ((implementedMethods & MethodFlags.SupportsExportTypeProc) != 0)
			{
				plugin.supportsExportTypeProc = new SupportsExportTypeProc(SupportsExportTypeProc);
				handles[i++] = GetHandle(plugin.supportsExportTypeProc);
			}
			if ((implementedMethods & MethodFlags.SupportsICCProfilesProc) != 0)
			{
				plugin.supportsICCProfilesProc = new SupportsICCProfilesProc(SupportsICCProfilesProc);
				handles[i++] = GetHandle(plugin.supportsICCProfilesProc);
			}

			// FormatProc is always implemented
			plugin.formatProc = new FormatProc(FormatProc);
			handles[i++] = GetHandle(plugin.formatProc);

			// InitProc is the register call back.
			initProc = new InitProc(RegisterProc);
			handles[i++] = GetHandle(initProc);

			// Register the plugin. The result will be saved and can be accessed later.
			registered = FreeImage.RegisterLocalPlugin(initProc, null, null, null, null) != FREE_IMAGE_FORMAT.FIF_UNKNOWN;
			if (registered)
			{
				PluginRepository.RegisterLocalPlugin(this);
			}
		}

		/// <summary>
		/// Releases all resources used by the instance.
		/// </summary>
		~LocalPlugin()
		{
			for (int i = 0; i < handles.Length; i++)
			{
				if (handles[i].IsAllocated)
				{
					handles[i].Free();
				}
			}
		}

		private GCHandle GetHandle(Delegate d)
		{
			return GCHandle.Alloc(d, GCHandleType.Normal);
		}

		private void RegisterProc(ref Plugin plugin, int format_id)
		{
			// Copy the function pointers
			plugin = this.plugin;
			// Retrieve the format if assigned to this plugin by FreeImage.
			format = (FREE_IMAGE_FORMAT)format_id;
		}

		/// <summary>
		/// Gets or sets if the plugin is enabled.
		/// </summary>
		public bool Enabled
		{
			get
			{
				if (registered)
				{
					return (FreeImage.IsPluginEnabled(format) > 0);
				}
				else
				{
					throw new ObjectDisposedException("plugin not registered");
				}
			}
			set
			{
				if (registered)
				{
					FreeImage.SetPluginEnabled(format, value);
				}
				else
				{
					throw new ObjectDisposedException("plugin not registered");
				}
			}
		}

		/// <summary>
		/// Gets if the plugin was registered successfully.
		/// </summary>
		public bool Registered
		{
			get { return registered; }
		}

		/// <summary>
		/// Gets the <see cref="FREE_IMAGE_FORMAT"/> FreeImage assigned to this plugin.
		/// </summary>
		public FREE_IMAGE_FORMAT Format
		{
			get
			{
				return format;
			}
		}

		/// <summary>
		/// Reads from an unmanaged stream.
		/// </summary>
		protected unsafe int Read(FreeImageIO io, fi_handle handle, uint size, uint count, ref byte[] buffer)
		{
			fixed (byte* ptr = buffer)
			{
				return (int)io.readProc(new IntPtr(ptr), size, count, handle);
			}
		}

		/// <summary>
		/// Reads a single byte from an unmanaged stream.
		/// </summary>
		protected unsafe int ReadByte(FreeImageIO io, fi_handle handle)
		{
			byte buffer = 0;
			return (int)io.readProc(new IntPtr(&buffer), 1, 1, handle) > 0 ? buffer : -1;
		}

		/// <summary>
		/// Writes to an unmanaged stream.
		/// </summary>
		protected unsafe int Write(FreeImageIO io, fi_handle handle, uint size, uint count, ref byte[] buffer)
		{
			fixed (byte* ptr = buffer)
			{
				return (int)io.writeProc(new IntPtr(ptr), size, count, handle);
			}
		}

		/// <summary>
		/// Writes a single byte to an unmanaged stream.
		/// </summary>
		protected unsafe int WriteByte(FreeImageIO io, fi_handle handle, byte value)
		{
			return (int)io.writeProc(new IntPtr(&value), 1, 1, handle);
		}

		/// <summary>
		/// Seeks in an unmanaged stream.
		/// </summary>
		protected int Seek(FreeImageIO io, fi_handle handle, int offset, SeekOrigin origin)
		{
			return io.seekProc(handle, offset, origin);
		}

		/// <summary>
		/// Retrieves the position of an unmanaged stream.
		/// </summary>
		protected int Tell(FreeImageIO io, fi_handle handle)
		{
			return io.tellProc(handle);
		}
	}
}