LibGfx/JBIG2Writer+Tests/LibGfx: Add support for files in random access organization

Tests/LibGfx/TestImageDecoder.cpp

@@ -334,6 +334,7 @@ TEST_CASE(test_jbig2_decode)
 
     Array test_inputs = {
         TEST_INPUT("jbig2/bitmap.jbig2"sv),
+        TEST_INPUT("jbig2/bitmap-randomaccess.jbig2"sv),
         TEST_INPUT("jbig2/bitmap-p32-eof.jbig2"sv),
         TEST_INPUT("jbig2/bitmap-initially-unknown-size.jbig2"sv),
         TEST_INPUT("jbig2/bitmap-composite-and-xnor.jbig2"sv),

Tests/LibGfx/test-inputs/jbig2/json/bitmap-randomaccess.json

@@ -0,0 +1,40 @@
+{
+    "global_header": {
+        "organization": "random_access",
+        "number_of_pages": 1
+    },
+    "segments": [
+        {
+            "segment_number": 0,
+            "type": "page_information",
+            "page_association": 1,
+            "data": {
+                "page_width": 399,
+                "page_height": 400,
+                "flags": {
+                    "is_eventually_lossless": true
+                }
+            }
+        },
+        {
+            "segment_number": 1,
+            "type": "lossless_generic_region",
+            "page_association": 1,
+            "data": {
+                "image_data": {
+                    "from_file": "bitmap.bmp"
+                }
+            }
+        },
+        {
+            "segment_number": 2,
+            "type": "end_of_page",
+            "page_association": 1
+        },
+        {
+            "segment_number": 3,
+            "type": "end_of_file",
+            "page_association": 0
+        }
+    ]
+}

Userland/Libraries/LibGfx/ImageFormats/JBIG2Writer.cpp

@@ -1537,9 +1537,16 @@ static ErrorOr<void> encode_jbig2_header(Stream& stream, JBIG2::FileHeaderData c
 
 namespace {
 
+struct SerializedSegmentData {
+    ByteBuffer data;
+    size_t header_size { 0 };
+};
+
 struct JBIG2EncodingContext {
     HashMap<u32, JBIG2::SegmentData const*> segment_by_id;
 
+    HashMap<u32, SerializedSegmentData> segment_data_by_id;
+
     HashMap<u32, Vector<JBIG2::Code>> codes_by_segment_id;
     HashMap<u32, JBIG2::HuffmanTable> tables_by_segment_id;
 
@@ -2487,7 +2494,7 @@ static ErrorOr<void> encode_extension(JBIG2::ExtensionData const& extension, Vec
     return {};
 }
 
-static ErrorOr<void> encode_segment(Stream& stream, JBIG2::SegmentData const& segment_data, JBIG2EncodingContext& context)
+static ErrorOr<SerializedSegmentData> encode_segment(JBIG2::SegmentData const& segment_data, JBIG2EncodingContext& context)
 {
     Vector<u8> scratch_buffer;
 
@@ -2597,16 +2604,23 @@ static ErrorOr<void> encode_segment(Stream& stream, JBIG2::SegmentData const& se
     header.data_length = segment_data.header.is_immediate_generic_region_of_initially_unknown_size ? 0xffff'ffff : encoded_data.size();
 
     auto page_association_size = segment_data.header.force_32_bit_page_association ? PageAssociationSize::Force32Bit : PageAssociationSize::Auto;
-    TRY(encode_segment_header(stream, header, page_association_size));
-    TRY(stream.write_until_depleted(encoded_data));
+    AllocatingMemoryStream header_stream;
+    TRY(encode_segment_header(header_stream, header, page_association_size));
+    auto header_data = TRY(header_stream.read_until_eof());
 
-    return {};
+    SerializedSegmentData data;
+    data.header_size = header_data.size();
+    data.data = TRY(ByteBuffer::create_uninitialized(header_data.size() + encoded_data.size()));
+    header_data.span().copy_to(data.data.span());
+    encoded_data.copy_to(data.data.span().slice(header_data.size()));
+
+    return data;
 }
 
 ErrorOr<void> JBIG2Writer::encode_with_explicit_data(Stream& stream, JBIG2::FileData const& file_data)
 {
-    if (file_data.header.organization != JBIG2::Organization::Sequential)
-        return Error::from_string_literal("JBIG2Writer: Can only encode sequential files yet");
+    if (file_data.header.organization == JBIG2::Organization::Embedded)
+        return Error::from_string_literal("JBIG2Writer: Can only encode sequential or random-access files");
 
     TRY(encode_jbig2_header(stream, file_data.header));
 
@@ -2617,7 +2631,26 @@ ErrorOr<void> JBIG2Writer::encode_with_explicit_data(Stream& stream, JBIG2::File
     }
 
     for (auto const& segment : file_data.segments) {
-        TRY(encode_segment(stream, segment, context));
+        auto data = TRY(encode_segment(segment, context));
+        VERIFY(context.segment_data_by_id.set(segment.header.segment_number, data) == HashSetResult::InsertedNewEntry);
+    }
+
+    if (file_data.header.organization == JBIG2::Organization::Sequential) {
+        for (auto const& segment : file_data.segments) {
+            auto const& data = context.segment_data_by_id.get(segment.header.segment_number);
+            TRY(stream.write_until_depleted(data->data));
+        }
+        return {};
+    }
+
+    VERIFY(file_data.header.organization == JBIG2::Organization::RandomAccess);
+    for (auto const& segment : file_data.segments) {
+        auto const& data = context.segment_data_by_id.get(segment.header.segment_number);
+        TRY(stream.write_until_depleted(data->data.span().slice(0, data->header_size)));
+    }
+    for (auto const& segment : file_data.segments) {
+        auto const& data = context.segment_data_by_id.get(segment.header.segment_number);
+        TRY(stream.write_until_depleted(data->data.span().slice(data->header_size)));
     }
 
     return {};