Hi there.
In this article I will briefly describe the process of using Windows' functions to load a bitmap (.bmp) file of any type, and place it on a newly-created DirectDraw surface. In this particular article, we will be using the DirectX 7.0 SDK.
[size="5"]DirectDraw Surface Creation
Creating a new DirectDraw surface is very easy, and this function will create a surface of any size. This can also be used as a general-purpose surface creation function, and if you were writing an engine class you'd probably put it in there somewhere.
Listing 1
void CreateSurface(LPDIRECTDRAWSURFACE7 *lpSource, int xs, int ys)
{
DDSURFACEDESC2 ddsd;
ZeroMemory(&ddsd, sizeof(ddsd));
ddsd.dwSize = sizeof(ddsd);
ddsd.dwFlags = DDSD_CAPS | DDSD_WIDTH | DDSD_HEIGHT;
ddsd.ddsCaps.dwCaps = DDSCAPS_OFFSCREENPLAIN;
ddsd.dwWidth = xs;
ddsd.dwHeight = ys;
lpdd->CreateSurface(&ddsd, lpSource, NULL);
}[size="5"]Bitmap Loading
To load .bmp files we will use the standard Windows graphics library (GDI). This is best because if we're in a mode with a palette then Windows will automatically re-map the bitmap colours to the nearest in the palette. Here is the code that blits a loaded bitmap to a surface....
Listing 2
void DrawHBitmap(IDirectDrawSurface7 *lpSurface, HBITMAP hBitmap, int x, int y, int width, int height)
{
HDC hdcImage;
HDC hdc;
BITMAP bm;
if (lpSurface == NULL || hBitmap == NULL)
return;
lpSurface->Restore();
hdcImage = CreateCompatibleDC(NULL);
SelectObject(hdcImage, hBitmap);
GetObject(hBitmap, sizeof(bm), &bm);
width = width == 0 ? bm.bmWidth : width;
height = height == 0 ? bm.bmHeight : height;
lpSurface->GetDC(&hdc);
BitBlt(hdc, x, y, width, height, hdcImage, 0, 0, SRCCOPY);
lpSurface->ReleaseDC(hdc);
DeleteDC(hdcImage);
}and here is the code that loads, blits, then unloads the bitmap:
Listing 3
void CreateBitmapSurface(LPDIRECTDRAWSURFACE7 lpSurface, char *fname, int xs, int ys)
{
HBITMAP hBitmap;
CreateSurface(&lpSurface, xs, ys);
hBitmap = LoadImage(NULL, fname, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
DrawHBitmap(lpSurface, hBitmap, 0, 0, xs, ys);
DeleteObject(hBitmap);
}[size="5"]Quick Example
And to round it all up, here's some example code that loads the file "test.bmp" (width = 128, height = 128) into the lpddsTest surface, and then releases it again:
Listing 4
void Example(void)
{
/*
* Declare the surface object
*/
LPDIRECTDRAWSURFACE7 lpddsTest;
/*
* Load the bitmap file into it
*/
CreateBitmapSurface(lpddsTest, "test.bmp", 128, 128);
/*
* The lpddsTest surface now contains the "test.bmp" file
*/
/*
* Release the surface
*/
lpddsTest->Release();
}
