Displaying image in WIN32, Why its not displayed? - c++

Question

I want to load a BitMap image in a pic box I created inside a window...picBoxDisp is created using following mechanism..
picBoxDisp = CreateWindow("STATIC", "image box",
WS_VISIBLE |WS_CHILD | SS_BITMAP |WS_TABSTOP | WS_BORDER,
50, 50, 250, 300, hwnd , (HMENU)10000, NULL, NULL);
Now Next I created a hBitmap object and loaded an image in to it...
hBitmap = (HBITMAP) LoadImage(NULL,szFileName,IMAGE_BITMAP,0,0,
LR_LOADFROMFILE| LR_DEFAULTSIZE);
SendMessage(picBoxDisp,STM_SETIMAGE,(WPARAM) IMAGE_BITMAP,(LPARAM) NULL);
//now assign the new image
//Create a compatible DC for the original size bitmap, for example originalMemDc.
HDC originalDC = GetDC((HWND)hBitmap);
HDC originalMemDC = CreateCompatibleDC(originalDC);
if(originalMemDC==NULL){
MessageBox(NULL,"Problem while creating DC.","Error",MB_OK);
}
//Select hBitmap into originalMemDc.
SelectObject(originalMemDC,hBitmap);
//Create a compatible DC for the resized bitmap, for example resizedMemDc.
HDC picBoxDC = GetDC(picBoxDisp);
HDC resizedMemDC = CreateCompatibleDC(picBoxDC);
//Create a compatible bitmap of the wanted size for the resized bitmap,
HBITMAP hResizedBitmap = CreateCompatibleBitmap(picBoxDC,250,300);
//Select hResizedBitmap into resizedMemDc.
SelectObject(resizedMemDC,hResizedBitmap);
//Stretch-blit from originalMemDc to resizedMemDc.
//BitBlt(resizedMemDC,0,0,250,300,originalMemDC,0,0,SRCCOPY);
BITMAP bmp_old,bmp_new;
GetObject(hBitmap,sizeof(bmp_old),&bmp_old);
GetObject(hResizedBitmap,sizeof(bmp_new),&bmp_new);
StretchBlt ( resizedMemDC,0,0,bmp_new.bmWidth,bmp_new.bmHeight,
originalMemDC,0,0,bmp_old.bmWidth,bmp_new.bmHeight,
SRCCOPY);
////De-select the bitmaps.
if((resizedMemDC==NULL)||(hResizedBitmap == NULL)) {
MessageBox(NULL,"Something is NULL","Error",MB_OK);
}
else
//Set hResizedBitmap as the label image with STM_SETIMAGE
SendMessage(picBoxDisp,STM_SETIMAGE, (WPARAM) IMAGE_BITMAP,(LPARAM) hResizedBitmap);
I just cant understand, why the above code is not working ?
Thanks in advance,

Answer 1

You misunderstood the STM_SETIMAGE usage. Do this:
hBitmap = (HBITMAP)::LoadImage(NULL, szFileName, IMAGE_BITMAP,
0, 0, LR_LOADFROMFILE| LR_DEFAULTSIZE);
if (hBitmap != NULL)
{
::SendMessage(picBoxDisp, STM_SETIMAGE,
(WPARAM)IMAGE_BITMAP, (LPARAM)hBitmap);
}
EDIT: If you want to resize the bitmap before setting it as the label image, then follow this scheme for the simplest possible way to do it (with sub-optimal quality in the resized image...):
Create a compatible DC for the original size bitmap, for example originalMemDc.
Select hBitmap into originalMemDc.
Create a compatible DC for the resized bitmap, for example resizedMemDc.
Create a compatible bitmap of the wanted size for the resized bitmap, for example hResizedBitmap.
Select hResizedBitmap into resizedMemDc.
Stretch-blit from originalMemDc to resizedMemDc.
De-select the bitmaps.
Set hResizedBitmap as the label image with STM_SETIMAGE
Should work!

Answer 2

The static control won't stretch the image to its size. You could use SS_CENTERIMAGE but it either clips or fills the empty space with the color of the top left pixel (see http://msdn.microsoft.com/en-US/library/b7w5x74z.aspx). You'd have to stretch the bitmap yourself before sending it to the static control.

Answer 3

You're trying to assign an image to a static control, so you don't need to draw the image but to set the image on it.
// set the image
HBITMAP hold = (HBITMAP)SendMessage(hpicBoxDc, STM_SETIMAGE, IMAGE_BITMAP, LPARAM(hBitmap));
// clear the old image
if(hold && hold != hBitmap)
DeleteObject(hold );