TBitmap.ReleaseHandle Method

Returns the handle to the bitmap so that the TBitmap object no longer knows about the handle.

Pascal

function ReleaseHandle: HBITMAP;

C++

__fastcall HBITMAP ReleaseHandle();

Description

Use ReleaseHandle to disassociate the bitmap from the bitmap handle. Use it when you need to give a bitmap handle to a routine or object that will assume ownership (or destroy) the bitmap handle.

C++ Examples:

Copy Code

/*
This example uses a button on a form and creates two bitmaps
dynamically.  One bitmap is monchrome, which means all
non-white colors become black.  The bitmap file path is
relative to the Debug directory.
Note: For the C++ Builder, capitalization matters for the file
name and path.
*/

#include <memory>       //for STL auto_ptr class

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  std::auto_ptr<Graphics::TBitmap> Bitmap1(new Graphics::TBitmap());
  std::auto_ptr<Graphics::TBitmap> Bitmap2(new Graphics::TBitmap());
  try
  {
    Bitmap1->LoadFromFile("..\\FACTORY.BMP");
    Bitmap2->Assign(Bitmap1.get());     // Copy Bitmap1 into Bitmap2
    Bitmap2->Dormant();           // Free up GDI resources
    Bitmap2->FreeImage();         // Free up Memory.
    Canvas->Draw(20, 20, Bitmap2.get());  // Note that previous calls don't lose the image
    Bitmap2->Monochrome = true;
    Canvas->Draw(80, 80, Bitmap2.get());
    Bitmap2->ReleaseHandle();       // This will actually lose the bitmap;
  }
  catch (...)
  {
    MessageBeep(0);
  }
}

Delphi Examples:

Copy Code

{
This example uses a button on a form and creates two bitmaps
dynamically.  One bitmap is monchrome, which means all
non-white colors become black.  The bitmap file path is
relative to the Debug directory.
}
procedure TForm1.Button1Click(Sender: TObject);
var
 BitMap1,BitMap2 : TBitMap;
 MyFormat : Word;
begin
   BitMap2 := TBitMap.Create;
   BitMap1 := TBitMap.Create;
try
   BitMap1.LoadFromFile('factory.bmp');
   BitMap2.Assign(BitMap1);     // Copy BitMap1 into BitMap2
   BitMap2.Dormant;             // Free up GDI resources
   BitMap2.FreeImage;           // Free up Memory.
   Canvas.Draw(20,20,BitMap2);  // Note that previous calls don't lose the image
   BitMap2.Monochrome := true;
   Canvas.Draw(80,80,BitMap2);
   BitMap2.ReleaseHandle;       // This will actually lose the bitmap;
 finally
   BitMap1.Free;
   BitMap2.Free;
 end;
end;