#include <memory>
#include <algorithm>
#include <vector>
#include <cassert>
#include <Classes.hpp>
//---------------------------------------------------------------------------
//Creates a std::vector that holds the ASCII art characters
//ordered from dark to light
std::vector<char> GetChars()
{
std::vector<char> chars;
chars.push_back('M');
chars.push_back('N');
chars.push_back('m');
chars.push_back('d');
chars.push_back('h');
chars.push_back('y');
chars.push_back('s');
chars.push_back('o');
chars.push_back('+');
chars.push_back('/');
chars.push_back(':');
chars.push_back('-');
chars.push_back('.');
chars.push_back('`');
chars.push_back(' ');
return chars;
}
//---------------------------------------------------------------------------
//Generalizes a rectangle to one grey value
double GetFractionGrey(
const TImage* const image,
const int x1,
const int y1,
const int x2,
const int y2)
{
assert(image!=0);
assert(image->Picture->Bitmap != 0);
assert(image->Picture->Bitmap->PixelFormat == pf32bit);
assert(x1 < image->Picture->Bitmap->Width);
assert(y1 < image->Picture->Bitmap->Height);
assert(x2 <= image->Picture->Bitmap->Width);
assert(y2 <= image->Picture->Bitmap->Height);
double sumGrey = 0.0;
int nPixels = 0;
for (int y=y1; y!=y2; ++y)
{
assert(y < image->Picture->Bitmap->Height);
const unsigned char * line
= static_cast<const unsigned char *>(image->Picture->Bitmap->ScanLine[y]);
for (int x=x1; x!=x2; ++x)
{
assert(x < image->Picture->Bitmap->Width);
//Note that in the line below, line[x*4+3] is not used.
//I guess that this is the alpha-blending value?
const int sumPixel = line[x*4+0] + line[x*4+1] + line[x*4+2];
assert( sumPixel < 3 * 256 );
const double grey
= static_cast<double>(sumPixel)
/ (3.0 * 255.0);
sumGrey+=grey;
++nPixels;
}
}
if (nPixels == 0)
{
//When the value is trivial, return a random value...
//Will not occur when nChars >= 5
return std::rand()%256;
}
else
{
const double fractionGrey = sumGrey / static_cast<double>(nPixels);
return fractionGrey;
}
}
//---------------------------------------------------------------------------
TStringList * ImageToAscii(
const TImage* const image,
const int charWidth) //How many chars the ASCII image will be wide
{
static const std::vector<char> chars(GetChars());
//If the number of chars is below 5,
//the calculation would be more complicated due to a too trivial value
assert(charWidth >= 5);
//Check the bitmap
assert(image->Picture->Bitmap != 0);
assert(image->Picture->Bitmap->PixelFormat == pf32bit);
//Maxy is in proportion with the bitmap
const int maxy =
(static_cast<double>(charWidth)
/ static_cast<double>(image->Picture->Bitmap->Width))
* static_cast<double>(image->Picture->Bitmap->Height);
assert(charWidth > 0);
assert(maxy > 0);
const double dX = static_cast<double>(image->Picture->Bitmap->Width)
/ static_cast<double>(charWidth);
const double dY = static_cast<double>(image->Picture->Bitmap->Height)
/ static_cast<double>(maxy);
assert(dX > 0.0);
assert(dY > 0.0);
TStringList * stringList = new TStringList;
for (int y=0; y!=maxy; ++y)
{
String myLine = "";
for (int x=0; x!=charWidth; ++x)
{
const int x1 = std::min(
static_cast<double>(x) * dX,
image->Picture->Bitmap->Width - 1.0) + 0.5;
const int y1 = std::min(
static_cast<double>(y) * dY,
image->Picture->Bitmap->Height - 1.0) + 0.5;
const int x2 = std::min(
(static_cast<double>(x) * dX) + dX,
image->Picture->Bitmap->Width - 1.0) + 0.5;
const int y2 = std::min(
(static_cast<double>(y) * dY) + dY,
image->Picture->Bitmap->Height - 1.0) + 0.5;
assert(x1 >= 0);
assert(x2 >= 0);
assert(y1 >= 0);
assert(y2 >= 0);
assert(x1 < image->Picture->Bitmap->Width);
assert(x2 < image->Picture->Bitmap->Width);
assert(y1 < image->Picture->Bitmap->Height);
assert(y2 < image->Picture->Bitmap->Height);
const double fGrey = std::min(std::max(0.0,
GetFractionGrey(image,x1,y1,x2,y2)),1.0);
assert(fGrey >= 0.0 && fGrey <= 1.0);
const double charIndex = fGrey
* static_cast<double>(chars.size() - 1);
assert(charIndex >= 0);
assert(charIndex < static_cast<int>(chars.size()));
const char thisChar = chars[charIndex];
myLine+=thisChar;
}
stringList->Add(myLine);
}
return stringList;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
const std::auto_ptr<TStringList> ascii(
ImageToAscii(Image1,Image1->Picture->Bitmap->Width));
Memo1->Lines = ascii.get();
}
//---------------------------------------------------------------------------
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