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LibGfx/JPEG: Make generate_huffman_codes be a method of HuffmanTable

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And call it when reading the table definition instead of when starting
to decode the stream.
This commit is contained in:
Lucas CHOLLET 2023-04-29 20:34:33 -04:00 committed by Andreas Kling
parent 8cba8ed25a
commit 9389177e5f
Notes: sideshowbarker 2024-07-17 06:46:15 +09:00 
Author: https://github.com/LucasChollet
Commit: https://github.com/SerenityOS/serenity/commit/9389177e5f
Pull-request: https://github.com/SerenityOS/serenity/pull/18583
Reviewed-by: https://github.com/IdanHo
Reviewed-by: https://github.com/gmta
1 changed files with 12 additions and 17 deletions
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29
Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
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@ -186,6 +186,16 @@ struct HuffmanTable {
u8 code_counts[16] = { 0 };
Vector<u8> symbols;
Vector<u16> codes;
void generate_codes()
{
unsigned code = 0;
for (auto number_of_codes : code_counts) {
for (int i = 0; i < number_of_codes; i++)
codes.append(code++);
code <<= 1;
}
}
};
class HuffmanStream {
@ -378,16 +388,6 @@ struct JPEGLoadingContext {
Optional<ByteBuffer> icc_data;
};
static void generate_huffman_codes(HuffmanTable& table)
{
unsigned code = 0;
for (auto number_of_codes : table.code_counts) {
for (int i = 0; i < number_of_codes; i++)
table.codes.append(code++);
code <<= 1;
}
}
static inline auto* get_component(Macroblock& block, unsigned component)
{
switch (component) {
@ -671,13 +671,6 @@ static void reset_decoder(JPEGLoadingContext& context)
static ErrorOr<void> decode_huffman_stream(JPEGLoadingContext& context, Vector<Macroblock>& macroblocks)
{
// Compute huffman codes for DC and AC tables.
for (auto it = context.dc_tables.begin(); it != context.dc_tables.end(); ++it)
generate_huffman_codes(it->value);
for (auto it = context.ac_tables.begin(); it != context.ac_tables.end(); ++it)
generate_huffman_codes(it->value);
for (u32 vcursor = 0; vcursor < context.mblock_meta.vcount; vcursor += context.vsample_factor) {
for (u32 hcursor = 0; hcursor < context.mblock_meta.hcount; hcursor += context.hsample_factor) {
u32 i = vcursor * context.mblock_meta.hpadded_count + hcursor;
@ -900,6 +893,8 @@ static ErrorOr<void> read_huffman_table(Stream& stream, JPEGLoadingContext& cont
table.symbols.append(symbol);
}
table.generate_codes();
auto& huffman_table = table.type == 0 ? context.dc_tables : context.ac_tables;
huffman_table.set(table.destination_id, table);
VERIFY(huffman_table.size() <= 2);