175 lines
6.2 KiB
C++
175 lines
6.2 KiB
C++
// jpge.h - C++ class for JPEG compression.
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// Public Domain or Apache 2.0, Richard Geldreich <richgel99@gmail.com>
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// Alex Evans: Added RGBA support, linear memory allocator.
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#ifndef JPEG_ENCODER_H
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#define JPEG_ENCODER_H
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namespace jpge
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{
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typedef unsigned char uint8;
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typedef signed short int16;
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typedef signed int int32;
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typedef unsigned short uint16;
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typedef unsigned int uint32;
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typedef unsigned int uint;
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// JPEG chroma subsampling factors. Y_ONLY (grayscale images) and H2V2 (color images) are the most common.
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enum subsampling_t { Y_ONLY = 0, H1V1 = 1, H2V1 = 2, H2V2 = 3 };
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// JPEG compression parameters structure.
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struct params
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{
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inline params() : m_quality(85), m_subsampling(H2V2), m_no_chroma_discrim_flag(false), m_two_pass_flag(false), m_use_std_tables(false) { }
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inline bool check() const
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{
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if ((m_quality < 1) || (m_quality > 100)) return false;
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if ((uint)m_subsampling > (uint)H2V2) return false;
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return true;
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}
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// Quality: 1-100, higher is better. Typical values are around 50-95.
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int m_quality;
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// m_subsampling:
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// 0 = Y (grayscale) only
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// 1 = YCbCr, no subsampling (H1V1, YCbCr 1x1x1, 3 blocks per MCU)
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// 2 = YCbCr, H2V1 subsampling (YCbCr 2x1x1, 4 blocks per MCU)
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// 3 = YCbCr, H2V2 subsampling (YCbCr 4x1x1, 6 blocks per MCU-- very common)
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subsampling_t m_subsampling;
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// Disables CbCr discrimination - only intended for testing.
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// If true, the Y quantization table is also used for the CbCr channels.
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bool m_no_chroma_discrim_flag;
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bool m_two_pass_flag;
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// By default we use the same quantization tables as mozjpeg's default.
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// Set to true to use the traditional tables from JPEG Annex K.
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bool m_use_std_tables;
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};
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// Writes JPEG image to a file.
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// num_channels must be 1 (Y) or 3 (RGB), image pitch must be width*num_channels.
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bool compress_image_to_jpeg_file(const char* pFilename, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params = params());
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// Writes JPEG image to memory buffer.
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// On entry, buf_size is the size of the output buffer pointed at by pBuf, which should be at least ~1024 bytes.
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// If return value is true, buf_size will be set to the size of the compressed data.
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bool compress_image_to_jpeg_file_in_memory(void* pBuf, int& buf_size, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params = params());
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// Output stream abstract class - used by the jpeg_encoder class to write to the output stream.
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// put_buf() is generally called with len==JPGE_OUT_BUF_SIZE bytes, but for headers it'll be called with smaller amounts.
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class output_stream
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{
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public:
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virtual ~output_stream() { };
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virtual bool put_buf(const void* Pbuf, int len) = 0;
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template<class T> inline bool put_obj(const T& obj) { return put_buf(&obj, sizeof(T)); }
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};
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// Lower level jpeg_encoder class - useful if more control is needed than the above helper functions.
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class jpeg_encoder
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{
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public:
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jpeg_encoder();
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~jpeg_encoder();
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// Initializes the compressor.
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// pStream: The stream object to use for writing compressed data.
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// params - Compression parameters structure, defined above.
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// width, height - Image dimensions.
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// channels - May be 1, or 3. 1 indicates grayscale, 3 indicates RGB source data.
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// Returns false on out of memory or if a stream write fails.
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bool init(output_stream* pStream, int width, int height, int src_channels, const params& comp_params = params());
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const params& get_params() const { return m_params; }
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// Deinitializes the compressor, freeing any allocated memory. May be called at any time.
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void deinit();
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uint get_total_passes() const { return m_params.m_two_pass_flag ? 2 : 1; }
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inline uint get_cur_pass() { return m_pass_num; }
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// Call this method with each source scanline.
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// width * src_channels bytes per scanline is expected (RGB or Y format).
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// You must call with NULL after all scanlines are processed to finish compression.
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// Returns false on out of memory or if a stream write fails.
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bool process_scanline(const void* pScanline);
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private:
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jpeg_encoder(const jpeg_encoder&);
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jpeg_encoder& operator =(const jpeg_encoder&);
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typedef int32 sample_array_t;
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output_stream* m_pStream;
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params m_params;
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uint8 m_num_components;
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uint8 m_comp_h_samp[3], m_comp_v_samp[3];
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int m_image_x, m_image_y, m_image_bpp, m_image_bpl;
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int m_image_x_mcu, m_image_y_mcu;
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int m_image_bpl_xlt, m_image_bpl_mcu;
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int m_mcus_per_row;
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int m_mcu_x, m_mcu_y;
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uint8* m_mcu_lines[16];
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uint8 m_mcu_y_ofs;
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sample_array_t m_sample_array[64];
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int16 m_coefficient_array[64];
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int32 m_quantization_tables[2][64];
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uint m_huff_codes[4][256];
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uint8 m_huff_code_sizes[4][256];
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uint8 m_huff_bits[4][17];
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uint8 m_huff_val[4][256];
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uint32 m_huff_count[4][256];
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int m_last_dc_val[3];
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enum { JPGE_OUT_BUF_SIZE = 2048 };
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uint8 m_out_buf[JPGE_OUT_BUF_SIZE];
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uint8* m_pOut_buf;
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uint m_out_buf_left;
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uint32 m_bit_buffer;
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uint m_bits_in;
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uint8 m_pass_num;
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bool m_all_stream_writes_succeeded;
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void optimize_huffman_table(int table_num, int table_len);
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void emit_byte(uint8 i);
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void emit_word(uint i);
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void emit_marker(int marker);
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void emit_jfif_app0();
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void emit_dqt();
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void emit_sof();
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void emit_dht(uint8* bits, uint8* val, int index, bool ac_flag);
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void emit_dhts();
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void emit_sos();
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void emit_markers();
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void compute_huffman_table(uint* codes, uint8* code_sizes, uint8* bits, uint8* val);
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void compute_quant_table(int32* dst, int16* src);
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void adjust_quant_table(int32* dst, int32* src);
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void first_pass_init();
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bool second_pass_init();
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bool jpg_open(int p_x_res, int p_y_res, int src_channels);
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void load_block_8_8_grey(int x);
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void load_block_8_8(int x, int y, int c);
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void load_block_16_8(int x, int c);
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void load_block_16_8_8(int x, int c);
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void load_quantized_coefficients(int component_num);
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void flush_output_buffer();
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void put_bits(uint bits, uint len);
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void code_coefficients_pass_one(int component_num);
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void code_coefficients_pass_two(int component_num);
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void code_block(int component_num);
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void process_mcu_row();
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bool terminate_pass_one();
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bool terminate_pass_two();
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bool process_end_of_image();
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void load_mcu(const void* src);
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void clear();
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void init();
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};
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} // namespace jpge
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#endif // JPEG_ENCODER
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