#include <windows.h>
#include <string.h>

Include dependency graph for alphablend.c:

Macros
#define	AC_SRC_ALPHA (0x1)

Functions
BOOL WINAPI	GdiAlphaBlend (HDC hdcDst, int xDst, int yDst, int widthDst, int heightDst, HDC hdcSrc, int xSrc, int ySrc, int widthSrc, int heightSrc, BLENDFUNCTION blendFunction)

LRESULT CALLBACK	MainWndProc (HWND HWnd, UINT Msg, WPARAM WParam, LPARAM LParam)

int APIENTRY	WinMain (HINSTANCE HInstance, HINSTANCE HPrevInstance, LPTSTR lpCmdLine, int nCmdShow)

BOOL	ConvertBitmapTo32Bpp (HDC hDC, BITMAP *bmp)

Variables
HINSTANCE	HInst

const char *	WndClassName = "GMainWnd"

BITMAP	bmp

LPCSTR	filename = TEXT("lena.bmp")

HDC	HMemDC = NULL

HDC	HMemDC2 = NULL

HBITMAP	HOldBmp = NULL

PVOID	pBmpBits = NULL

HBITMAP	H32BppBitmap = NULL

BITMAPINFO	bmpi

Macro Definition Documentation

◆ AC_SRC_ALPHA

#define AC_SRC_ALPHA (0x1)

Definition at line 9 of file alphablend.c.

Function Documentation

◆ ConvertBitmapTo32Bpp()

BOOL ConvertBitmapTo32Bpp	(	HDC	hDC,
		BITMAP *	bmp
	)

Definition at line 70 of file alphablend.c.

{
  ZeroMemory(&bmpi, sizeof(BITMAPINFO));
  bmpi.bmiHeader.biSize = sizeof(BITMAPINFO);
  bmpi.bmiHeader.biWidth = bmp->bmWidth;
  bmpi.bmiHeader.biHeight = bmp->bmHeight;
  bmpi.bmiHeader.biPlanes = 1;
  bmpi.bmiHeader.biBitCount = 32;
  bmpi.bmiHeader.biCompression = BI_RGB;
  bmpi.bmiHeader.biSizeImage = 4 * bmpi.bmiHeader.biWidth * bmpi.bmiHeader.biHeight;
  H32BppBitmap = CreateDIBSection(hDC, &bmpi, DIB_RGB_COLORS, &pBmpBits, 0, 0);
  if(H32BppBitmap)
  {
    HBITMAP bmpalpha;
    SelectObject(hDC, H32BppBitmap);
    BitBlt(hDC, 0, 0, bmp->bmWidth, bmp->bmHeight, HMemDC, 0, 0, SRCCOPY);
 
    /* load and apply alpha channel */
    bmpalpha = LoadImage(HInst, MAKEINTRESOURCE(2000), IMAGE_BITMAP,
                            0, 0, 0);
    if(bmpalpha)
    {
      COLORREF *col = pBmpBits;
      int x, y;
      HDC hdcTemp = CreateCompatibleDC(NULL);
      if(!hdcTemp)
      {
        DeleteObject(bmpalpha);
        return FALSE;
      }
      SelectObject(hdcTemp, bmpalpha);
 
      for(y = 0; y < bmp->bmHeight; y++)
      {
        for(x = 0; x < bmp->bmWidth; x++)
        {
          COLORREF Color = (COLORREF)GetRValue(GetPixel(hdcTemp, x, y)) << 24;
          *col++ |= Color;
        }
      }
 
      DeleteObject(bmpalpha);
      DeleteDC(hdcTemp);
      return TRUE;
    }
    return FALSE;
  }
  return FALSE;
}

Referenced by MainWndProc().

◆ GdiAlphaBlend()

BOOL WINAPI GdiAlphaBlend	(	HDC	hdcDst,
		int	xDst,
		int	yDst,
		int	widthDst,
		int	heightDst,
		HDC	hdcSrc,
		int	xSrc,
		int	ySrc,
		int	widthSrc,
		int	heightSrc,
		BLENDFUNCTION	blendFunction
	)

Referenced by alpha_blend_image(), draw_graphics(), DrawShadowText(), gdi_alpha_blend(), MainWndProc(), OnDrawItem(), and PlayEnhMetaFileRecord().

◆ MainWndProc()

LRESULT CALLBACK MainWndProc	(	HWND	HWnd,
		UINT	Msg,
		WPARAM	WParam,
		LPARAM	LParam
	)

Definition at line 120 of file alphablend.c.

{
   switch (Msg)
   {
      case WM_CREATE:
      {
         /* create a memory DC */
         HMemDC = CreateCompatibleDC(NULL);
         if (HMemDC)
         {
            /* load a bitmap from file */
            HBITMAP HBmp =
               /* static_cast<HBITMAP> */(
                  LoadImage(HInst, MAKEINTRESOURCE(1000), IMAGE_BITMAP,
                            0, 0, 0)
                            );
            if (HBmp)
            {
               /* extract dimensions of the bitmap */
               GetObject(HBmp, sizeof(BITMAP), &bmp);
 
               /* associate the bitmap with the memory DC */
               /* HOldBmp = static_cast<HBITMAP> */
        (SelectObject(HMemDC, HBmp)
                  );
                HMemDC2 = CreateCompatibleDC(NULL);
                if(!ConvertBitmapTo32Bpp(HMemDC2, &bmp))
                {
                  PostQuitMessage(0);
                  return 0;
                }
            }
         }
      }
      case WM_PAINT:
      {
         PAINTSTRUCT ps;
         BLENDFUNCTION BlendFunc;
         HDC Hdc = BeginPaint(HWnd, &ps);
#if 0
         try
#endif
         {
 
            BlendFunc.BlendOp = AC_SRC_OVER;
            BlendFunc.BlendFlags = 0;
            BlendFunc.SourceConstantAlpha = 128;
            BlendFunc.AlphaFormat = 0;
 
            BitBlt(Hdc, 100, 90,
                   bmp.bmWidth, bmp.bmHeight,
                   HMemDC2, 0, 0,
                   SRCCOPY);
            GdiAlphaBlend(Hdc, 0, 0, bmp.bmWidth, bmp.bmHeight,
                          HMemDC2, 0, 0, bmp.bmWidth, bmp.bmHeight,
                          BlendFunc);
            GdiAlphaBlend(Hdc, bmp.bmWidth - 15, 10, bmp.bmWidth / 2, bmp.bmHeight / 2,
                          HMemDC2, 0, 0, bmp.bmWidth, bmp.bmHeight,
                          BlendFunc);
 
            BlendFunc.SourceConstantAlpha = 255;
            BlendFunc.AlphaFormat = AC_SRC_ALPHA;
 
            GdiAlphaBlend(Hdc, 140, 200, bmp.bmWidth, bmp.bmHeight,
                          HMemDC2, 0, 0, bmp.bmWidth, bmp.bmHeight,
                          BlendFunc);
            GdiAlphaBlend(Hdc, 20, 210, (bmp.bmWidth / 3) * 2, (bmp.bmHeight / 3) * 2,
                          HMemDC2, 0, 0, bmp.bmWidth, bmp.bmHeight,
                          BlendFunc);
         }
#if 0
         catch (...)
         {
            EndPaint(HWnd, &ps);
         }
#endif
         EndPaint(HWnd, &ps);
         break;
      }
      case WM_DESTROY:
      {
         /* clean up */
         DeleteObject(SelectObject(HMemDC, HOldBmp));
         DeleteDC(HMemDC);
         DeleteDC(HMemDC2);
 
         PostQuitMessage(0);
         return 0;
      }
   }
   return DefWindowProc(HWnd, Msg, WParam, LParam);
}

Referenced by WinMain().

◆ WinMain()

int APIENTRY WinMain	(	HINSTANCE	HInstance,
		HINSTANCE	HPrevInstance,
		LPTSTR	lpCmdLine,
		int	nCmdShow
	)

Definition at line 17 of file alphablend.c.

{
   WNDCLASS wc;
   MSG msg;
 
   HInst = HInstance;
 
   memset(&wc, 0, sizeof(WNDCLASS));
 
   wc.style = CS_VREDRAW | CS_HREDRAW | CS_DBLCLKS;
   wc.lpfnWndProc = MainWndProc;
   wc.hInstance = HInstance;
   wc.hCursor = LoadCursor(NULL, (LPCTSTR)IDC_ARROW);
  /* wc.hbrBackground = reinterpret_cast<HBRUSH>(COLOR_BTNFACE + 1); */
   wc.hbrBackground = (HBRUSH)(COLOR_BTNFACE + 1);
   wc.lpszClassName = WndClassName;
 
   if (RegisterClass(&wc))
   {
      HWND HWnd =
         CreateWindow(
            WndClassName, TEXT("AlphaBlend Rendering Demo"),
            WS_OVERLAPPED | WS_SYSMENU | WS_CAPTION |
            WS_VISIBLE | WS_CLIPSIBLINGS,
            0, 0, 320, 430,
            NULL, NULL, HInst, NULL
            );
 
      if (HWnd)
      {
         ShowWindow(HWnd, nCmdShow);
         UpdateWindow(HWnd);
 
         while (GetMessage(&msg, NULL, 0, 0))
         {
             TranslateMessage(&msg);
             DispatchMessage(&msg);
         }
      }
    }
    return 0;
}