LibGfx/TIFF: Extract metadata-related definition to their own file

Userland/Libraries/LibGfx/ImageFormats/TIFFMetadata.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2023, Lucas Chollet <lucas.chollet@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Variant.h>
+#include <AK/Vector.h>
+#include <LibGfx/Size.h>
+
+namespace Gfx {
+
+namespace TIFF {
+
+enum class Type {
+    Byte = 1,
+    ASCII = 2,
+    UnsignedShort = 3,
+    UnsignedLong = 4,
+    UnsignedRational = 5,
+    Undefined = 7,
+    SignedLong = 9,
+    SignedRational = 10,
+    Float = 11,
+    Double = 12,
+    UTF8 = 129,
+};
+
+template<OneOf<u32, i32> x32>
+struct Rational {
+    using Type = x32;
+    x32 numerator;
+    x32 denominator;
+};
+
+using Value = Variant<u8, String, u16, u32, Rational<u32>, i32, Rational<i32>>;
+
+// This enum is progessively defined across sections but summarized in:
+// Appendix A: TIFF Tags Sorted by Number
+enum class Compression {
+    NoCompression = 1,
+    CCITT = 2,
+    Group3Fax = 3,
+    Group4Fax = 4,
+    LZW = 5,
+    JPEG = 6,
+    PackBits = 32773,
+};
+
+enum class Predictor {
+    None = 1,
+    HorizontalDifferencing = 2,
+};
+
+}
+
+struct Metadata {
+    IntSize size {};
+    Array<u16, 3> bits_per_sample {};
+    TIFF::Compression compression {};
+    TIFF::Predictor predictor {};
+    Vector<u32> strip_offsets {};
+    u32 rows_per_strip {};
+    Vector<u32> strip_bytes_count {};
+};
+
+}