(C++ VCL) SurfacePlotter

The TChart Component does not support a surface plot. Therefore I post this class to draw surface plots.

//---------------------------------------------------------------------------
//#Include guard
ifndef UnitSurfacePlotterSingleH

define UnitSurfacePlotterSingleH

//---------------------------------------------------------------------------
// Surface plotter
// C++ VCL class written by Bilderbikkel
// Feel free to copy it, use it and credit me
//---------------------------------------------------------------------------
//STL headers
include <vector>

include <algorithm>

include <cassert>

//Boost headers
include <boost/scoped_ptr.hpp>

//VCL headers
include <Graphics.hpp>

include <ExtCtrls.hpp>

//---------------------------------------------------------------------------
struct SurfacePlotter
{
  SurfacePlotter()
  : mImage(new Extctrls::TImage(0))
  {
    mImage->AutoSize = true;
    mImage->Visible = false;
    mImage->Stretch = false;
    assert(FileExists("1x1.bmp"));
    mImage->Picture->LoadFromFile("1x1.bmp");
  }
  //Sets the image of the surface plot to the values of the vector
  //The doubles can be in any range
  void setSurfaceGrey(const std::vector<std::vector<double> >& surface)
  {
    //Get the size
    const int maxx = surface.size();
    const int maxy = surface[0].size();
    //Resize Image to the correct size
    mImage->Picture->Bitmap->Width  = maxx;
    mImage->Picture->Bitmap->Height = maxy;
    //Minimum and maximum are not given, so these need to be calculated
    double minVal = *(std::min_element(surface[0].begin(),surface[0].end()));
    double maxVal = *(std::max_element(surface[0].begin(),surface[0].end()));
    for (int x=1; x!=maxx; ++x)
    {
      const double localMinVal = *(std::min_element(surface[x].begin(),surface[x].end()));
      const double localMaxVal = *(std::max_element(surface[x].begin(),surface[x].end()));
      if (localMinVal < minVal) minVal = localMinVal;
      if (localMaxVal > maxVal) maxVal = localMaxVal;
    }
    //Draw the pixels
    for (int y=0; y!=maxy; ++y)
    {
      unsigned char * line
        = static_cast<unsigned char *>(mImage->Picture->Bitmap->ScanLine[y]);
      for (int x=0; x!=maxx; ++x)
      {
        const double greyValueDouble = (surface[x][y] - minVal) / (maxVal - minVal);
        assert(greyValueDouble >= 0.0 && greyValueDouble <= 1.0);
        const char greyValue = greyValueDouble * 255.0;
        line[x*3+0] = greyValue; //Blue
        line[x*3+1] = greyValue; //Green
        line[x*3+2] = greyValue; //Red
      }
    }
  }
  //Sets the image of the surface plot to the values of the vector
  //Assumes that the chars are in the range [0,255] (a char's range)
  //If the chars are in a shorter range, they will NOT be rescaled to [0,255]
  void setSurfaceGrey(const std::vector<std::vector<char> >& surface)
  {
    const int maxx = surface.size();
    const int maxy = surface[0].size();
    mImage->Picture->Bitmap->Width = maxx;
    mImage->Picture->Bitmap->Height = maxy;
    for (int y=0; y!=maxy; ++y)
    {
      unsigned char * line
        = static_cast<unsigned char *>(mImage->Picture->Bitmap->ScanLine[y]);
      for (int x=0; x!=maxx; ++x)
      {
        const char greyValue = surface[x][y];
        line[x*3+0] = greyValue; //Blue
        line[x*3+1] = greyValue; //Green
        line[x*3+2] = greyValue; //Red
      }
    }
  }
  //Draws the surface plot to the canvas given
  void draw(const int& x, const int& y, TCanvas * canvas) const
  {
    canvas->Draw(x,y,mImage->Picture->Graphic);
  }
  private:
  boost::scoped_ptr<TImage> mImage;
};
endif

Usage example:

void __fastcall TForm1::Button1Click(TObject*)
{
  const int maxx = 256;
  const int maxy = 128;
  std::vector<std::vector<double> > test(
    maxx,std::vector<double>(maxy,0.0)); //Black
  for (int y=0; y!=maxy; ++y)
  {
    for (int x=0; x!=maxx; ++x)
    {
      test[x][y] 
        = std::cos(x / 10.0) 
        + std::sin(y / 15.0) 
        + std::cos((x+y)/20.0);
    }
  }
  SurfacePlotter s;
  s.setSurfaceGrey(test);
  s.draw(0,0,Canvas);
}

Code links

last edited (November 18, 2006) by bilderbikkel, Number of views: 2329, Current Rev: 8 (Diff)

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