Src/encode.c (LibJPEG_Encoding)

100

101

102

/** ****************************************************************************** * @file LibJPEG/LibJPEG_Encoding/Src/encode.c * @author MCD Application Team * @brief This file contain the compress method. ****************************************************************************** * @attention * * Copyright (c) 2017 STMicroelectronics. * All rights reserved. * * This software is licensed under terms that can be found in the LICENSE file * in the root directory of this software component. * If no LICENSE file comes with this software, it is provided AS-IS. * ****************************************************************************** */ /* Includes ------------------------------------------------------------------*/ #include "encode.h" /* Private typedef -----------------------------------------------------------*/ /* This struct contains the JPEG compression parameters */ static struct jpeg_compress_struct cinfo_; /* This struct represents a JPEG error handler */ struct jpeg_error_mgr jerr_; /* Private define ------------------------------------------------------------*/ /* Private macro -------------------------------------------------------------*/ /* Private variables ---------------------------------------------------------*/ /* Private function prototypes -----------------------------------------------*/ /* Private functions ---------------------------------------------------------*/ /** * @brief Jpeg encode * @param file: pointer to the bmp file * @param file1: pointer to the jpg file * @param width: image width * @param height: image height * @param image_quality: image quality * @param buff: pointer to the image line * @retval None */ void jpeg_encode(JFILE *file, JFILE *file1, uint32_t width, uint32_t height, uint32_t image_quality, uint8_t * buff) { /* Encode BMP Image to JPEG */ /* Pointer to a single row */ JSAMPROW row_pointer; uint32_t bytesread; uint32_t index; /* Step 1: allocate and initialize JPEG compression object */ /* Set up the error handler */ cinfo_.err = jpeg_std_error(&jerr_); /* Initialize the JPEG compression object */ jpeg_create_compress(&cinfo_); /* Step 2: specify data destination */ jpeg_stdio_dest(&cinfo_, file1); /* Step 3: set parameters for compression */ cinfo_.image_width = width; cinfo_.image_height = height; cinfo_.input_components = 3; cinfo_.in_color_space = JCS_RGB; /* Set default compression parameters */ jpeg_set_defaults(&cinfo_); cinfo_.dct_method = JDCT_FLOAT; jpeg_set_quality(&cinfo_, image_quality, TRUE); /* Step 4: start compressor */ jpeg_start_compress(&cinfo_, TRUE); /* Get bitmap data address offset */ f_read(file, buff, 14, (UINT*)&bytesread); index = *(__IO uint16_t *) (buff + 10); index |= (*(__IO uint16_t *) (buff + 12)) << 16; while (cinfo_.next_scanline < cinfo_.image_height) { /* In this application, the input file is a BMP, which first encodes the bottom of the picture */ /* JPEG encodes the highest part of the picture first. We need to read the lines upside down */ /* Move the read pointer to 'last line of the picture - next_scanline' */ f_lseek(file, ((cinfo_.image_height-1-cinfo_.next_scanline)*width*3)+index); if(f_read(file, buff, width*3, (UINT*)&bytesread) == FR_OK) { row_pointer = (JSAMPROW)buff; jpeg_write_scanlines(&cinfo_, &row_pointer, 1); } } /* Step 5: finish compression */ jpeg_finish_compress(&cinfo_); /* Step 6: release JPEG compression object */ jpeg_destroy_compress(&cinfo_); }