(C++) HDC

Windows data type for a handle to a device context.

An HDC can be obtained by GetDC (among others) and must be released by ReleaseDC. Use Scoped_hdc for safe memory use.

HDC is declared in windef.h (at least in the library that shipped with C++ Builder 6.0).

Example: MakeScreenshot

MakeScreenshot retrieves the HDC of the desktop and copies it (using BitBlt) on a bitmap (or more specific: a Graphics::TBitmap).

MakeScreenshot uses the VCL data type Graphics::TBitmap supplied with C++ Builder 6.0.


#include <cassert>

#include <windows.h>

#include <Extctrls.hpp>

//From http://www.richelbilderbeek.nl/CppMakeScreenshot.htm

void MakeScreenshot(Graphics::TBitmap * const b)

{

  assert(b);

  assert(b->PixelFormat == pf32bit);

  const HDC desktop = GetDC(0);

  b->Width  = Screen->Width;

  b->Height = Screen->Height;

  BitBlt(b->Canvas->Handle, 0, 0, b->Width, b->Height, desktop, 0, 0, SRCCOPY);

  b->Modified = true;

  ReleaseDC(0, desktop);

}

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