(C++ VCL) ScanLine

TBitmap method returning a void* to the indexed row of a bitmap, which can be used for quick low-level graphics.

Example using TImage

Image1->Visible = false;
const int maxx = Image1->Width;
const int maxy = Image1->Height;
for (int y = 0; y != maxy; ++y)
{
  unsigned char * myLine = 
    static_cast<unsigned char*>(Image1->Picture->Bitmap->ScanLine[y]);
  for (int x = 0; x != maxx; ++x)
  {
    myLine[x*3+2] = x  ; //Red  
    myLine[x*3+1] = y  ; //Green  
    myLine[x*3+0] = x+y; //Blue  
  }
}
//Actually draw it on Form1
Form1->Canvas->Draw(0,0,Image1->Picture->Graphic);

The function ScanLine returns a void*, therefore it needs to be cast to an unsigned char pointer. Note that red, green and blue are reversed in the obtained pointer. Also note that the image can be drawn on the screen entirely after the graphical operation. I've made the TImage invisible in the first line. This avoids flicker.

ScanLine links

C++ CLX ScanLine
Pascal VCL ScanLine
Pascal CLX ScanLine

Code links

char
const
for
?Form1
int

last edited (November 18, 2006) by bilderbikkel, Number of views: 2098, Current Rev: 5 (Diff)

[Edit this page] [Page history] [What links here] [Discuss this topic] [Printer Friendly]