[ADD] - Jpeg to bmp

Added a function jpeg_to_bmp that converts JPEG images to BMP format. The function reads the input JPEG file, initializes a JPEG decompressor, and extracts image dimensions and pixel data. It then constructs a BMP header, calculates the BMP file size, and writes the header to the output BMP file. The JPEG pixel data is rearranged and written in RGB order to the BMP file. Padding is added as needed to align rows on a 4-byte boundary. The function ensures memory is properly managed, closes files, and provides conversion status output.

Author: VerzatileDev

src/converters/jpeg_to_bmp.c

@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <jpeglib.h>
+
+int jpeg_to_bmp(const char *input_filename, const char *output_filename)
+{
+    FILE *input_file = fopen(input_filename, "rb");
+    if (!input_file)
+    {
+        fprintf(stderr, "Error: could not open input file %s\n", input_filename);
+        return 1;
+    }
+    
+    // Initialize JPEG decompressor object
+    struct jpeg_decompress_struct cinfo;
+    struct jpeg_error_mgr jerr;
+    cinfo.err = jpeg_std_error(&jerr);
+    jpeg_create_decompress(&cinfo);
+    
+    // Specify input file for JPEG decompressor
+    jpeg_stdio_src(&cinfo, input_file);
+    jpeg_read_header(&cinfo, TRUE);
+    jpeg_start_decompress(&cinfo);
+    
+    // Get image dimensions
+    int width = cinfo.output_width;
+    int height = cinfo.output_height;
+    
+    // Allocate memory for JPEG image data
+    unsigned char *jpeg_data = (unsigned char *)malloc(width * height * cinfo.output_components);
+    if (!jpeg_data)
+    {
+        fprintf(stderr, "Error: could not allocate memory for JPEG image data\n");
+        fclose(input_file);
+        jpeg_destroy_decompress(&cinfo);
+        return 1;
+    }
+    
+    // Read JPEG image data
+    while (cinfo.output_scanline < cinfo.output_height)
+    {
+        JSAMPROW row_pointer = &jpeg_data[(cinfo.output_height - cinfo.output_scanline - 1) * width * cinfo.output_components];
+        jpeg_read_scanlines(&cinfo, &row_pointer, 1);
+    }
+    
+    // Finish decompression
+    jpeg_finish_decompress(&cinfo);
+    
+    // Close JPEG file
+    fclose(input_file);
+    jpeg_destroy_decompress(&cinfo);
+    
+    // Open output BMP file for writing
+    FILE *output_file = fopen(output_filename, "wb");
+    if (!output_file)
+    {
+        fprintf(stderr, "Error: could not open output file %s\n", output_filename);
+        free(jpeg_data);
+        return 1;
+    }
+    
+    // Write BMP header
+    unsigned char bmp_header[54] = {
+        'B', 'M',                     // Signature
+        0, 0, 0, 0,                   // File size (to be filled later)
+        0, 0, 0, 0,                   // Reserved
+        54, 0, 0, 0,                  // Offset to pixel data
+        40, 0, 0, 0,                  // Header size
+        0, 0, 0, 0,                   // Image width (to be filled later)
+        0, 0, 0, 0,                   // Image height (to be filled later)
+        1, 0,                         // Number of color planes
+        24, 0,                        // Bits per pixel (3 bytes)
+        0, 0, 0, 0,                   // Compression method
+        0, 0, 0, 0,                   // Image size (can be 0)
+        0, 0, 0, 0,                   // Horizontal resolution (can be 0)
+        0, 0, 0, 0,                   // Vertical resolution (can be 0)
+        0, 0, 0, 0,                   // Number of colors in palette (0 for 24-bit)
+        0, 0, 0, 0                    // Number of important colors (can be 0)
+    };
+    
+    int bmp_file_size = sizeof(bmp_header) + width * height * 3;
+    bmp_header[2] = (unsigned char)(bmp_file_size);
+    bmp_header[3] = (unsigned char)(bmp_file_size >> 8);
+    bmp_header[4] = (unsigned char)(bmp_file_size >> 16);
+    bmp_header[5] = (unsigned char)(bmp_file_size >> 24);
+    bmp_header[18] = (unsigned char)(width);
+    bmp_header[19] = (unsigned char)(width >> 8);
+    bmp_header[20] = (unsigned char)(width >> 16);
+    bmp_header[21] = (unsigned char)(width >> 24);
+    bmp_header[22] = (unsigned char)(height);
+    bmp_header[23] = (unsigned char)(height >> 8);
+    bmp_header[24] = (unsigned char)(height >> 16);
+    bmp_header[25] = (unsigned char)(height >> 24);
+    
+    fwrite(bmp_header, sizeof(unsigned char), sizeof(bmp_header), output_file);
+    
+    // Write BMP image data
+    for (int y = height - 1; y >= 0; y--)
+    {
+        for (int x = 0; x < width; x++)
+        {
+            int jpeg_index = (height - y - 1) * width * cinfo.output_components + x * cinfo.output_components;
+            fwrite(&jpeg_data[jpeg_index + 2], sizeof(unsigned char), 1, output_file); // Blue
+            fwrite(&jpeg_data[jpeg_index + 1], sizeof(unsigned char), 1, output_file); // Green
+            fwrite(&jpeg_data[jpeg_index + 0], sizeof(unsigned char), 1, output_file); // Red
+        }
+        
+        // Write padding if necessary (multiple of 4 bytes)
+        for (int p = 0; p < (4 - (width * 3) % 4) % 4; p++)
+        {
+            fputc(0, output_file);
+        }
+    }
+    
+    fclose(output_file);
+    printf("Converted %s to %s\n", input_filename, output_filename);
+    
+    return 0;
+}

src/main.c

@@ -2,13 +2,15 @@
 //#include "converters/bmp_to_jpeg.c" // Include this line to test the bmp_to_jpeg function
 //#include "converters/bmp_to_png.c"
 //#include "converters/png_to_bmp.c"
+//#include "converters/jpeg_to_bmp.c"
 
 int main(int argc, char **argv)
 {
     //Include the following line to test the bmp_to_jpeg function
     //bmp_to_jpeg("assets/images/test_image.bmp", "assets/images/testjpg.jpg");
     //bmp_to_png("assets/images/test_image_negative.bmp", "assets/images/testpng.png");
     //png_to_bmp("assets/images/testpng.png", "assets/images/test_i.bmp");
+    //jpeg_to_bmp("assets/images/testjpg.jpg", "assets/images/test_j.bmp");
 
     GtkApplication *app;
     int status;