Add support for XCF (#450)

Author: somebody1234

core.d.ts

@@ -10,6 +10,7 @@ declare namespace core {
 		| 'gif'
 		| 'webp'
 		| 'flif'
+		| 'xcf'
 		| 'cr2'
 		| 'cr3'
 		| 'orf'
@@ -146,6 +147,7 @@ declare namespace core {
 		| 'image/gif'
 		| 'image/webp'
 		| 'image/flif'
+		| 'image/x-xcf'
 		| 'image/x-canon-cr2'
 		| 'image/x-canon-cr3'
 		| 'image/tiff'

core.js

@@ -1051,6 +1051,13 @@ async function _fromTokenizer(tokenizer) {
 		};
 	}
 
+	if (checkString('gimp xcf ')) {
+		return {
+			ext: 'xcf',
+			mime: 'image/x-xcf'
+		};
+	}
+
 	// -- 12-byte signatures --
 
 	if (check([0x49, 0x49, 0x55, 0x00, 0x18, 0x00, 0x00, 0x00, 0x88, 0xE7, 0x74, 0xD8])) {

fixture/fixture.xcf

@@ -54,6 +54,7 @@
 		"gif",
 		"webp",
 		"flif",
+		"xcf",
 		"cr2",
 		"cr3",
 		"orf",

package.json

@@ -278,6 +278,7 @@ Returns a set of supported MIME types.
 - [`gif`](https://en.wikipedia.org/wiki/GIF) - Graphics Interchange Format
 - [`webp`](https://en.wikipedia.org/wiki/WebP) - Web Picture format
 - [`flif`](https://en.wikipedia.org/wiki/Free_Lossless_Image_Format) - Free Lossless Image Format
+- [`xcf`](https://en.wikipedia.org/wiki/XCF_(file_format)) - eXperimental Computing Facility
 - [`cr2`](https://fileinfo.com/extension/cr2) - Canon Raw image file (v2)
 - [`cr3`](https://fileinfo.com/extension/cr3) - Canon Raw image file (v3)
 - [`orf`](https://en.wikipedia.org/wiki/ORF_format) - Olympus Raw image file

readme.md

@@ -8,6 +8,7 @@ module.exports = {
 		'gif',
 		'webp',
 		'flif',
+		'xcf',
 		'cr2',
 		'cr3',
 		'orf',
@@ -144,6 +145,7 @@ module.exports = {
 		'image/gif',
 		'image/webp',
 		'image/flif',
+		'image/x-xcf',
 		'image/x-canon-cr2',
 		'image/x-canon-cr3',
 		'image/tiff',