CheckerBoardFast.cpp

Faster method to create a checkerboard pattern in a memory image view The image is written tile by tile, using a buffer to write the tile values at once.

Faster method to create a checkerboard pattern in a memory image view The image is written tile by tile, using a buffer to write the tile values at once.

#include <chrono>
#include <iostream>
#include <vector>
 
#include <iolink/view/ImageViewFactory.h>
 
using namespace iolink;
 
std::shared_ptr<ImageView>
checkerBoard_Fast(const size_t sideLength)
{
  // a checker board is always square
  const VectorXu64 shape{sideLength, sideLength};
  // a checkerboard is black and white, so we use UINT8 pixel type
  const DataType dt = DataTypeId::UINT8;
 
  // create an image view in memory
  auto image = ImageViewFactory::allocate(shape, dt);
 
  // a checkerboard contains 10 tiles in both direction
  const size_t tileCount = 10;
  const VectorXu64 tileSize = shape / tileCount;
  RegionXu64 tileRegion = RegionXu64::createFullRegion(tileSize);
 
  // allocate a buffer to write a tile (black or white) at once
  std::vector<uint8_t> blackTileBuffer(tileRegion.elementCount(), 0);
  std::vector<uint8_t> whiteTileBuffer(tileRegion.elementCount(), 255);
 
  // draw tiles in the image tile by tile
  for (size_t i = 0; i < tileCount; ++i)
  {
    for (size_t j = 0; j < tileCount; ++j)
    {
      // compute the origin position of the region to write
      VectorXu64 origin = VectorXu64{i, j} * tileSize;
      RegionXu64 currentTileRegion(origin, tileSize);
 
      // write the black or white tile depending on the tile index parity
      if ((i + j) % 2 == 0)
        image->writeRegion(currentTileRegion, blackTileBuffer.data());
      else
        image->writeRegion(currentTileRegion, whiteTileBuffer.data());
    }
  }
 
  return image;
}
 
int
main(int argc, char** argv)
{
  std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
 
  auto image = checkerBoard_Fast(1000);
 
  std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
  std::cout << "Checkerboard (fast method) generated in "
            << std::chrono::duration_cast<std::chrono::microseconds>(end - begin).count() << " microseconds"
            << std::endl;
 
  std::cout << "Generated ImageView: " << image->toString() << std::endl;
 
  return EXIT_SUCCESS;
}