further dissection of bmp headers

CMakeLists.txt

@@ -9,7 +9,7 @@ FetchContent_Declare(
         GIT_REPOSITORY  https://github.com/fmtlib/fmt
         GIT_TAG         10.2.1
 )
-FETCHCONTENT_MAKEAVAILABLE(fmt)
+FetchContent_MakeAvailable(fmt)
 
 add_executable(steganography main.cpp
         read_picture.h

dib_headers.h

@@ -26,8 +26,8 @@ struct BITMAPINFOHEADER {
     uint32_t header_size;
     int width;
     int height;
-    uint16_t num_color_planes;
-    uint16_t bits_per_pixel; // wikipedia says must be 1
+    uint16_t num_color_planes; // wikipedia says must be 1
+    uint16_t bytes_per_pixel;
     uint32_t compression_method;
     uint32_t raw_bitmap_data_size;
     int horizontal_resolution;

main.cpp

@@ -10,7 +10,7 @@ void display_file_info(std::filesystem::path const& file) {
     fmt::println("Size: {} bytes",file_size(file));
     std::string extension = file.extension().string();
     if(extension == ".bmp"){
-        fmt::println("Extension: {} - The BMP file format or bitmap, is a raster graphics image file format used to store bitmap digital images, independently of the display device (such as a graphics adapter), especially on Microsoft Windows[2] and OS/2[3] operating systems.", file.extension().string());
+        fmt::println("Extension: {} - The BMP file format or bitmap,\nis a raster graphics image file format used to store bitmap digital images, independently of the display device\n(such as a graphics adapter), especially on Microsoft Windows[2] and OS/2[3] operating systems.", file.extension().string());
         auto bmp_info = bmp_reader::read_bmp(file);
     }
     else if(extension == ".ppm"){

read_picture.cpp

@@ -19,6 +19,10 @@ void bmp_reader::parse_header(std::ifstream& stream, file_header& header) {
 void bmp_reader::parse_dib(std::ifstream &stream, dib_header &dib) {
     stream.read((char*)&dib.dib_size, 4);
     fmt::println("DIB Header size: {}", dib.dib_size);
+    auto pos = stream.tellg();
+    pos -= 4;
+    stream.seekg(pos);
+
     switch(dib.dib_size) {
         case 12: // BITMAPCOREHEADER OS21XBITMAPHEADER
 
@@ -28,6 +32,27 @@ void bmp_reader::parse_dib(std::ifstream &stream, dib_header &dib) {
 
             break;
         case 40: // BITMAPINFOHEADER
+            fmt::println("Bitmap header type: BITMAPINFOHEADER");
+            BITMAPINFOHEADER header;
+            stream.read((char*)&header, 40);
+            fmt::println("Bitmap Width: {}\nBitmap Height: {}", header.width, header.height);
+            fmt::println("Color planes: {}", header.num_color_planes);
+            fmt::println("Bytes per pixel: {}", header.bytes_per_pixel);
+            fmt::println("Compression method: {}", header.compression_method);
+            fmt::println("Bitmap data size: {}", header.raw_bitmap_data_size);
+            fmt::println("Horizontal resolution: {}", header.horizontal_resolution);
+            fmt::println("Vertical resolution: {}", header.vertical_resolution);
+            fmt::println("Color pallette: {}", header.num_palette_colors);
+            fmt::println("Important colors: {}", header.num_important_colors);
+
+            // Current offset from file start ->52 = 12 (bmp header) + 40 (DIB BITMAPINFOHEADER)
+
+            if(header.compression_method != 0){
+                fmt::println("Unsupported bitmap compression method: {}", header.compression_method);
+                exit(-1);
+            }
+
+            stream.seekg(stream.tellg()+())
 
             break;
         case 52: // BITMAPV2INFOHEADER

read_picture.h

@@ -31,6 +31,9 @@ namespace bmp_reader {
     void parse_header(std::ifstream& stream, file_header& header);
     void parse_dib(std::ifstream& stream, dib_header& dib);
 
+
+    auto parse_bitmapinfoheader(std::ifstream& stream) -> BITMAPINFOHEADER;
+
     auto read_bmp(std::filesystem::path const& file) -> bmp_data;
 }