(C++ CLX) Graphics

Graphics in the CLX can be accomplished using a TPaintBox or a TImage component. The first is easier, yet slower and gives flicker.

Example using TPaintBox

const unsigned int maxx = PaintBox1->Width;
const unsigned int maxy = PaintBox1->Height;
for (unsigned int y = 0; y < maxy; ++y)
{
  for (unsigned int x = 0; x < maxx; ++x)
  {
    PaintBox1->Canvas->Pixels[x][y] = RGB(x,y,x+y);
  } //Next y 
} //Next x

RGB is a macro. TPaintBox gets updated after every change in pixel. This makes it slow.

Example using TImage

Put a TImage on the Form called Image1 (this is the default name). Set the Picture Property to a 32 bitmap (created in for example MS Paint).

assert(Image1->Picture->Bitmap->PixelFormat == pf32bit); //Assume a 32 bitmap
const unsigned int maxx = Image1->Picture->Bitmap->Width;
const unsigned int maxy = Image1->Picture->Bitmap->Height;
for (unsigned int y = 0; y != maxy; ++y)
{
  unsigned char * const myLine 
    = static_cast<unsigned char* const>(
      Image1->Picture->Bitmap->ScanLine[y]); //CLX is not const correct. Grumble, grumble...
  for (unsigned int x = 0; x != maxx; ++x)
  {
    //myLine[x*4+3] = (x+y)%256; //Alpha blending?
    myLine[x*4+2] = (x  )%256; //Red
    myLine[x*4+1] = (  y)%256; //Green
    myLine[x*4+0] = (x+y)%256; //Blue
  }
}
//Add these lines below if you want to StretchDraw it on your Form
//assert(Image1->Visible == false);
//this->Canvas->StretchDraw(this->ClientRect, Image1->Picture->Graphic); //Assumes you work in a Form's method

The function ScanLine returns a void pointer, therefore it needs to be cast to an unsigned char pointer. Note that red, green and blue are reversed in the obtained pointer.

Example using double-buffering

Work in progress...

'Graphics' links

general
C
C++
C++ Builder
C++ VCL
Pascal CLX
Pascal VCL

last edited (July 3, 2007) by bilderbikkel, Number of views: 2158, Current Rev: 5 (Diff)

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