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125 lines
4.5 KiB
C
125 lines
4.5 KiB
C
//------------------------------------------------------------------------------
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// picojpeg - Public domain, Rich Geldreich <richgel99@gmail.com>
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//------------------------------------------------------------------------------
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#ifndef PICOJPEG_H
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#define PICOJPEG_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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// Error codes
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enum {
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PJPG_NO_MORE_BLOCKS = 1,
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PJPG_BAD_DHT_COUNTS,
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PJPG_BAD_DHT_INDEX,
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PJPG_BAD_DHT_MARKER,
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PJPG_BAD_DQT_MARKER,
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PJPG_BAD_DQT_TABLE,
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PJPG_BAD_PRECISION,
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PJPG_BAD_HEIGHT,
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PJPG_BAD_WIDTH,
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PJPG_TOO_MANY_COMPONENTS,
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PJPG_BAD_SOF_LENGTH,
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PJPG_BAD_VARIABLE_MARKER,
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PJPG_BAD_DRI_LENGTH,
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PJPG_BAD_SOS_LENGTH,
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PJPG_BAD_SOS_COMP_ID,
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PJPG_W_EXTRA_BYTES_BEFORE_MARKER,
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PJPG_NO_ARITHMITIC_SUPPORT,
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PJPG_UNEXPECTED_MARKER,
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PJPG_NOT_JPEG,
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PJPG_UNSUPPORTED_MARKER,
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PJPG_BAD_DQT_LENGTH,
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PJPG_TOO_MANY_BLOCKS,
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PJPG_UNDEFINED_QUANT_TABLE,
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PJPG_UNDEFINED_HUFF_TABLE,
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PJPG_NOT_SINGLE_SCAN,
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PJPG_UNSUPPORTED_COLORSPACE,
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PJPG_UNSUPPORTED_SAMP_FACTORS,
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PJPG_DECODE_ERROR,
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PJPG_BAD_RESTART_MARKER,
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PJPG_ASSERTION_ERROR,
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PJPG_BAD_SOS_SPECTRAL,
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PJPG_BAD_SOS_SUCCESSIVE,
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PJPG_STREAM_READ_ERROR,
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PJPG_NOTENOUGHMEM,
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PJPG_UNSUPPORTED_COMP_IDENT,
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PJPG_UNSUPPORTED_QUANT_TABLE,
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PJPG_UNSUPPORTED_MODE, // picojpeg doesn't support progressive JPEG's
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};
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// Scan types
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typedef enum { PJPG_GRAYSCALE, PJPG_YH1V1, PJPG_YH2V1, PJPG_YH1V2, PJPG_YH2V2 } pjpeg_scan_type_t;
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typedef struct {
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// Image resolution
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int m_width;
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int m_height;
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// Number of components (1 or 3)
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int m_comps;
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// Total number of minimum coded units (MCU's) per row/col.
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int m_MCUSPerRow;
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int m_MCUSPerCol;
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// Scan type
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pjpeg_scan_type_t m_scanType;
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// MCU width/height in pixels (each is either 8 or 16 depending on the scan type)
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int m_MCUWidth;
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int m_MCUHeight;
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// m_pMCUBufR, m_pMCUBufG, and m_pMCUBufB are pointers to internal MCU Y or RGB pixel component buffers.
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// Each time pjpegDecodeMCU() is called successfully these buffers will be filled with 8x8 pixel blocks of Y or RGB
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// pixels. Each MCU consists of (m_MCUWidth/8)*(m_MCUHeight/8) Y/RGB blocks: 1 for greyscale/no subsampling, 2 for
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// H1V2/H2V1, or 4 blocks for H2V2 sampling factors. Each block is a contiguous array of 64 (8x8) bytes of a single
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// component: either Y for grayscale images, or R, G or B components for color images.
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//
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// The 8x8 pixel blocks are organized in these byte arrays like this:
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//
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// PJPG_GRAYSCALE: Each MCU is decoded to a single block of 8x8 grayscale pixels.
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// Only the values in m_pMCUBufR are valid. Each 8 bytes is a row of pixels (raster order: left to right, top to
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// bottom) from the 8x8 block.
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//
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// PJPG_H1V1: Each MCU contains is decoded to a single block of 8x8 RGB pixels.
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//
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// PJPG_YH2V1: Each MCU is decoded to 2 blocks, or 16x8 pixels.
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// The 2 RGB blocks are at byte offsets: 0, 64
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//
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// PJPG_YH1V2: Each MCU is decoded to 2 blocks, or 8x16 pixels.
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// The 2 RGB blocks are at byte offsets: 0,
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// 128
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//
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// PJPG_YH2V2: Each MCU is decoded to 4 blocks, or 16x16 pixels.
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// The 2x2 block array is organized at byte offsets: 0, 64,
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// 128, 192
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//
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// It is up to the caller to copy or blit these pixels from these buffers into the destination bitmap.
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unsigned char* m_pMCUBufR;
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unsigned char* m_pMCUBufG;
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unsigned char* m_pMCUBufB;
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} pjpeg_image_info_t;
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typedef unsigned char (*pjpeg_need_bytes_callback_t)(unsigned char* pBuf, unsigned char buf_size,
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unsigned char* pBytes_actually_read, void* pCallback_data);
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// Initializes the decompressor. Returns 0 on success, or one of the above error codes on failure.
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// pNeed_bytes_callback will be called to fill the decompressor's internal input buffer.
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// If reduce is 1, only the first pixel of each block will be decoded. This mode is much faster because it skips the AC
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// dequantization, IDCT and chroma upsampling of every image pixel. Not thread safe.
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unsigned char pjpeg_decode_init(pjpeg_image_info_t* pInfo, pjpeg_need_bytes_callback_t pNeed_bytes_callback,
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void* pCallback_data, unsigned char reduce);
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// Decompresses the file's next MCU. Returns 0 on success, PJPG_NO_MORE_BLOCKS if no more blocks are available, or an
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// error code. Must be called a total of m_MCUSPerRow*m_MCUSPerCol times to completely decompress the image. Not thread
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// safe.
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unsigned char pjpeg_decode_mcu(void);
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#ifdef __cplusplus
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}
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#endif
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#endif // PICOJPEG_H
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