Merge pull request PintaProject#216 from MrCarroll/MimeTypeFilter

Use MIME filters for file dialogs on non-Windows systems

Pinta.Core/Actions/LayerActions.cs

@@ -181,6 +181,18 @@ private void HandlePintaCoreActionsLayersImportFromFileActivated (object sender,
 				}
 			}
 
+			// On Unix-like systems, file extensions are often considered optional.
+			// Files can often also be identified by their MIME types.
+			// Windows does not understand MIME types natively.
+			// Adding a MIME filter on Windows would break the native file picker and force a GTK file picker instead.
+			if (SystemManager.GetOperatingSystem() != OS.Windows) {
+				foreach (var format in PintaCore.System.ImageFormats.Formats) {
+					foreach (var mime in format.Mimes) {
+						ff.AddMimeType (mime);
+					}
+				}
+			}
+
 			ff.Name = Translations.GetString ("Image files");
 			fcd.AddFilter (ff);
 

Pinta.Core/ImageFormats/FormatDescriptor.cs

@@ -43,6 +43,11 @@ public sealed class FormatDescriptor
 		/// </summary>
 		public string[] Extensions { get; private set; }
 
+		/// <summary>
+		/// A list of supported MIME types (for example, "image/jpg" and "image/png").
+		/// </summary>
+		public string[] Mimes { get; private set; }
+
 		/// <summary>
 		/// The importer for this file format. This may be null if only exporting
 		/// is supported for this format.
@@ -65,16 +70,18 @@ public sealed class FormatDescriptor
 		/// in the file dialog's filter.
 		/// </param>
 		/// <param name="extensions">A list of supported file extensions (for example, "jpeg" and "JPEG").</param>
+		/// <param name="mimes">A list of supported file MIME types (for example, "image/jpeg" and "image/png").</param>
 		/// <param name="importer">The importer for this file format, or null if importing is not supported.</param>
 		/// <param name="exporter">The exporter for this file format, or null if exporting is not supported.</param>
-		public FormatDescriptor (string displayPrefix, string[] extensions,
+		public FormatDescriptor (string displayPrefix, string[] extensions, string[] mimes,
 					 IImageImporter? importer, IImageExporter? exporter)
 		{
 			if (extensions == null || (importer == null && exporter == null)) {
 				throw new ArgumentNullException ("Format descriptor is initialized incorrectly");
 			}
 
 			this.Extensions = extensions;
+			this.Mimes = mimes;
 			this.Importer = importer;
 			this.Exporter = exporter;
 
@@ -90,6 +97,16 @@ public FormatDescriptor (string displayPrefix, string[] extensions,
 				formatNames.Append (wildcard);
 			}
 
+			// On Unix-like systems, file extensions are often considered optional.
+			// Files can often also be identified by their MIME types.
+			// Windows does not understand MIME types natively.
+			// Adding a MIME filter on Windows would break the native file picker and force a GTK file picker instead.
+			if (SystemManager.GetOperatingSystem() != OS.Windows) {
+				foreach (string mime in mimes) {
+					ff.AddMimeType (mime);
+				}
+			}
+
 			ff.Name = string.Format (Translations.GetString ("{0} image ({1})"), displayPrefix, formatNames);
 			this.Filter = ff;
 		}

Pinta.Core/Managers/ImageConverterManager.cs

@@ -70,12 +70,12 @@ public ImageConverterManager ()
 				else
 					exporter = null;
 
-				RegisterFormat (new FormatDescriptor (formatNameUpperCase, extensions, importer, exporter));
+				RegisterFormat (new FormatDescriptor (formatNameUpperCase, extensions, format.MimeTypes, importer, exporter));
 			}
 
 			// Create all the formats we have our own importers/exporters for
 			OraFormat oraHandler = new OraFormat ();
-			RegisterFormat (new FormatDescriptor ("OpenRaster", new string[] { "ora", "ORA" }, oraHandler, oraHandler));
+			RegisterFormat (new FormatDescriptor ("OpenRaster", new string[] { "ora", "ORA" }, new string[] { "image/openraster" }, oraHandler, oraHandler));
 		}
 
 		public IEnumerable<FormatDescriptor> Formats { get { return formats; } }

Pinta/Actions/File/OpenDocumentAction.cs

@@ -65,6 +65,18 @@ private void Activated (object sender, EventArgs e)
 				}
 			}
 
+			// On Unix-like systems, file extensions are often considered optional.
+			// Files can often also be identified by their MIME types.
+			// Windows does not understand MIME types natively.
+			// Adding a MIME filter on Windows would break the native file picker and force a GTK file picker instead.
+			if (SystemManager.GetOperatingSystem() != OS.Windows) {
+				foreach (var format in PintaCore.System.ImageFormats.Formats) {
+					foreach (var mime in format.Mimes) {
+						ff.AddMimeType (mime);
+					}
+				}
+			}
+
 			fcd.AddFilter (ff);
 
 			var ff2 = new FileFilter {