ScanLine (C++)

Description

This example shows how to draw directly to a Bitmap. It loads a bitmap from a file and then copies it to another bitmap twice its size. Then the two bitmaps are displayed on the form canvas.

Code

#include <memory>       //For STL auto_ptr class

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  std::auto_ptr<Graphics::TBitmap> Bitmap(new Graphics::TBitmap);
  std::auto_ptr<Graphics::TBitmap> BigBitmap(new Graphics::TBitmap);
  TRGBTriple *ptr, *bigPtr;   // Use a (byte *) for pf8bit color.
  TPixelFormat pixForm, bigpixForm;
  try
  {
	Bitmap->LoadFromFile("../littlefac.bmp");
	pixForm = Bitmap->PixelFormat;
	bigpixForm  = BigBitmap->PixelFormat;
	Bitmap->PixelFormat = pf24bit;
	BigBitmap->PixelFormat = pf24bit;
	BigBitmap->Height = Bitmap->Height * 2;
	BigBitmap->Width = Bitmap->Width * 2;
	for (int y = 0; y < Bitmap->Height; y++)
    {
	  ptr = reinterpret_cast<TRGBTriple *>(Bitmap->ScanLine[y]);
	  for (int x = 0; x < Bitmap->Width; x++)
	  {
		int bx = x * 2;
		int by = y * 2;
		bigPtr = reinterpret_cast<TRGBTriple *>(BigBitmap->ScanLine[by]);
		bigPtr[bx] = ptr[x];
		bigPtr[bx + 1] = ptr[x];
		bigPtr = reinterpret_cast<TRGBTriple *>(BigBitmap->ScanLine[by + 1]);
		bigPtr[bx] = ptr[x];
		bigPtr[bx + 1] = ptr[x];
	  }
	}
	Canvas->Draw(0, 0, Bitmap.get());
	Canvas->Draw(200, 200, BigBitmap.get());
  }
  catch (...)
  {
    ShowMessage("Could not load or alter bitmap");
  }
}

Uses

• Vcl.Graphics.TBitmap.ScanLine ( fr | de | ja )
• Vcl.Graphics.TGraphic.Height ( fr | de | ja )
• Vcl.Graphics.TGraphic.Width ( fr | de | ja )
• Vcl.Graphics.TBitmap.PixelFormat ( fr | de | ja )