Win API: Bitmaps
Author
I want to create a bitmap in photoshop and use it for my application as the background. How can I load a bitmap and display it using the windows API. An explanation or a link to one would be great. I already tried looking through MSDN but I couldnt find it.
Essentially, the process will be that you load the bitmap (LoadBitmap), create a memory-DC (GetDC on the window, then CreateCompatibleDC), select the bitmap into the memory-DC (SelectObject), then copy from the memory-dc to the window-dc (BitBlt or StretchBlt).
Author
How can I manually add a bitmap to a rc file because Im not using the IDE's resource editor and if i do it will screw up all the other resources.
Author
yea right after i posted i went DUH! lol so ive got that, and ive gotten to the last function call. Im a bit confused on what the destination dc and what the source dc are.
What I have so far:
Confusing Prototype:
What I have so far:
HANDLE hmainbg = LoadBitmap(hmaininstance,"test.bmp");HDC hmaindc = GetDC(hmainwnd);CreatCompatibleDC(hmaindc);SelectObject(hmaindc,hmainbg);Confusing Prototype:
BOOL BitBlt( HDC hdcDest, // handle to destination DC int nXDest, // x-coord of destination upper-left corner int nYDest, // y-coord of destination upper-left corner int nWidth, // width of destination rectangle int nHeight, // height of destination rectangle HDC hdcSrc, // handle to source DC int nXSrc, // x-coordinate of source upper-left corner int nYSrc, // y-coordinate of source upper-left corner DWORD dwRop // raster operation code);
The source DC is the DC that contains the bitmap and the destination DC is the DC that you are going to paint to. Here is an example:
// Add this to your dialog's window procedure - it will be called when the// dialog needs to be repaintedcase WM_PAINT: { PAINTSTRUCT ps; // hmaindc will be the DC of your window HDC hmaindc = BegainPaint(hwnd, &ps); // hmemorydc will hold hmainbg so that we can paint it to the window HDC hmemorydc = CreateCompatibleDC(hmaindc); // Of course we have to load the bitmap itself HBITMAP hmainbg = LoadBitmap(hmaininstance, "test.bmp"); // When we select hmainbg into hmemorydc we must hold the original // bitmap (which is returned) so that we can return the DC to its original // state before we delete it HBITMAP holdbmp = (HBITMAP)SelectObject(hmemorydc, hmainbg); // Before we draw the bitmap, let's get some information about it // This includes its width and height BITMAP bmpinfo; GetObject(hmainbg, sizeof(bmpinfo), &bmpinfo); // Now we can draw hmainbg to the window using BitBlt() BitBlt(hmaindc, 0, 0, bmpinfo.bmWidth, bmpinfo.bmHeight, hmemorydc, 0, 0, SRCCOPY); // Now the painting is done so we begin to clean up // First selelect the original bitmap into the memory DC SelectObject(hmemorydc, holdbmp); // Now delete the bitmap DeleteObject(hmainbg); // And then the memory DC DeleteDC(hmemorydc); // And finally, end the painting process EndPaint(hwnd, &ps); break;}
If you're loading the bitmap from a resource file, HANDLE hmainbg = LoadBitmap(hmaininstance,"test.bmp"); is incorrect. You only specify the file name if you're loading from a file. Otherwise, you have to use some macro (MAKEINTORESOURCE or MAKEINTRESOURCE or something like that)
Author
This is what I have so far, no success.
HBITMAP hmainbg = LoadBitmap(hmaininstance,"test.bmp"); HDC hmaindc = GetDC(hmainwnd); HDC hmemdc = CreateCompatibleDC(hmaindc); HBITMAP holdbmp = (HBITMAP)SelectObject(hmemdc,hmainbg); BitBlt(hmemdc,0,0,325,300,hmaindc,0,0,SRCCOPY); SelectObject(hmemdc, holdbmp); DeleteObject(hmainbg); DeleteDC(hmemdc);
i have no clue if this will work..but here it goes
load the bitmap into the resource file
or have it available to be opened as a file
in the callback for messages put this in there
switch(msg){
...code in there already....
case WM_ERASEBKGND:
HBITMAP bmp=LoadBitmap(hinst,MAKEINTRESORCE(resource id for bitmap));
HDC hDCbg=(HDC)wParam;
RECT rc;
GetClientRect(hwnd,&rc);
HDC hdctemp=CreateCompatibleDC(hDCbg);
SelectObject(hdctemp,bmp);
BitBlt(hDCbg,rc.top,rc.left,rc.bottom-rc.top,rc.right-rc.left,hdctemp,0,0,SRCPAINT);
DeleteObject(hdctemp);
DeleteObject(bmp);
return 0;
that should work...some of the functions may be mixed up, but that is supposed to reapaint the background with a bitmap
to use a file and not a resource use
HBITMAP bmp=LoadBitmap(hinst,"c:/filename.bmp");
load the bitmap into the resource file
or have it available to be opened as a file
in the callback for messages put this in there
switch(msg){
...code in there already....
case WM_ERASEBKGND:
HBITMAP bmp=LoadBitmap(hinst,MAKEINTRESORCE(resource id for bitmap));
HDC hDCbg=(HDC)wParam;
RECT rc;
GetClientRect(hwnd,&rc);
HDC hdctemp=CreateCompatibleDC(hDCbg);
SelectObject(hdctemp,bmp);
BitBlt(hDCbg,rc.top,rc.left,rc.bottom-rc.top,rc.right-rc.left,hdctemp,0,0,SRCPAINT);
DeleteObject(hdctemp);
DeleteObject(bmp);
return 0;
that should work...some of the functions may be mixed up, but that is supposed to reapaint the background with a bitmap
to use a file and not a resource use
HBITMAP bmp=LoadBitmap(hinst,"c:/filename.bmp");
by the way..anybody know how to use the wave api to record?...
off topic i know
the WM_ERASEBKGROUND message is made for drawing the background
wparam is the hdc, beats haveing to fool with WM_PAINT and possibly replacing the entire window with your bitmap, after all you said background
WM_PAINT is to draw the entire window ( even the box, menu, everything)
off topic i know
the WM_ERASEBKGROUND message is made for drawing the background
wparam is the hdc, beats haveing to fool with WM_PAINT and possibly replacing the entire window with your bitmap, after all you said background
WM_PAINT is to draw the entire window ( even the box, menu, everything)
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
