RenderD7 is now LibRenderD7

source/bmpconverter.cpp

@@ -0,0 +1,106 @@
+#include <renderd7/bmpconverter.hpp>
+
+namespace BitmapConverter{
+
+//returns 0 if all went ok, non-0 if error
+//output image is always given in RGBA (with alpha channel), even if it's a BMP without alpha channel
+unsigned decodeBMP(std::vector<unsigned char>& image, unsigned& w, unsigned& h, const std::vector<unsigned char>& bmp) {
+  static const unsigned MINHEADER = 54; //minimum BMP header size
+
+  if(bmp.size() < MINHEADER) return -1;
+  if(bmp[0] != 'B' || bmp[1] != 'M') return 1; //It's not a BMP file if it doesn't start with marker 'BM'
+  unsigned pixeloffset = bmp[10] + 256 * bmp[11]; //where the pixel data starts
+  //read width and height from BMP header
+  w = bmp[18] + bmp[19] * 256;
+  h = bmp[22] + bmp[23] * 256;
+  //read number of channels from BMP header
+  if(bmp[28] != 24 && bmp[28] != 32) return 2; //only 24-bit and 32-bit BMPs are supported.
+  unsigned numChannels = bmp[28] / 8;
+
+  //The amount of scanline bytes is width of image times channels, with extra bytes added if needed
+  //to make it a multiple of 4 bytes.
+  unsigned scanlineBytes = w * numChannels;
+  if(scanlineBytes % 4 != 0) scanlineBytes = (scanlineBytes / 4) * 4 + 4;
+
+  unsigned dataSize = scanlineBytes * h;
+  if(bmp.size() < dataSize + pixeloffset) return 3; //BMP file too small to contain all pixels
+
+  image.resize(w * h * 4);
+
+  /*
+  There are 3 differences between BMP and the raw image buffer for LodePNG:
+  -it's upside down
+  -it's in BGR instead of RGB format (or BRGA instead of RGBA)
+  -each scanline has padding bytes to make it a multiple of 4 if needed
+  The 2D for loop below does all these 3 conversions at once.
+  */
+  for(unsigned y = 0; y < h; y++)
+  for(unsigned x = 0; x < w; x++) {
+    //pixel start byte position in the BMP
+    unsigned bmpos = pixeloffset + (h - y - 1) * scanlineBytes + numChannels * x;
+    //pixel start byte position in the new raw image
+    unsigned newpos = 4 * y * w + 4 * x;
+    if(numChannels == 3) {
+      image[newpos + 0] = bmp[bmpos + 2]; //R
+      image[newpos + 1] = bmp[bmpos + 1]; //G
+      image[newpos + 2] = bmp[bmpos + 0]; //B
+      image[newpos + 3] = 255;            //A
+    } else {
+      image[newpos + 0] = bmp[bmpos + 2]; //R
+      image[newpos + 1] = bmp[bmpos + 1]; //G
+      image[newpos + 2] = bmp[bmpos + 0]; //B
+      image[newpos + 3] = bmp[bmpos + 3]; //A
+    }
+  }
+  return 0;
+}
+
+std::vector<unsigned char> ConvertFile(std::string filename) {
+
+  std::vector<unsigned char> bmp;
+  lodepng::load_file(bmp, filename);
+  
+  std::vector<unsigned char> image;
+  unsigned w, h;
+  unsigned error = BitmapConverter::decodeBMP(image, w, h, bmp);
+
+  if(error) {
+    std::cout << "BMP decoding error " << error << std::endl;
+    
+  }
+
+  std::vector<unsigned char> png;
+  error = lodepng::encode(png, image, w, h);
+
+  if(error) {
+    std::cout << "PNG encoding error " << error << ": " << lodepng_error_text(error) << std::endl;
+    
+  }
+
+  return png;
+
+}
+
+std::vector<unsigned char> ConvertData(std::vector<unsigned char> data) {
+  
+  std::vector<unsigned char> image;
+  unsigned w, h;
+  unsigned error = BitmapConverter::decodeBMP(image, w, h, data);
+
+  if(error) {
+    std::cout << "BMP decoding error " << error << std::endl;
+    
+  }
+
+  std::vector<unsigned char> png;
+  error = lodepng::encode(png, image, w, h);
+
+  if(error) {
+    std::cout << "PNG encoding error " << error << ": " << lodepng_error_text(error) << std::endl;
+    
+  }
+
+  return png;
+
+}
+}