Si y a pas de moyens "directs, l'API StretchBlt sait faire.
StretchBlt function copies a bitmap from a source rectangle into a destination rectangle, stretching or compressing the bitmap to fit the dimensions of the destination rectangle, if necessary. Windows stretches or compresses the bitmap according to the stretching mode currently set in the destination device context.
BOOL StretchBlt(
HDC hdcDest, // handle of destination device context
int nXOriginDest, // x-coordinate of upper-left corner of dest. rect.
int nYOriginDest, // y-coordinate of upper-left corner of dest. rect.
int nWidthDest, // width of destination rectangle
int nHeightDest, // height of destination rectangle
HDC hdcSrc, // handle of source device context
int nXOriginSrc, // x-coordinate of upper-left corner of source rectangle
int nYOriginSrc, // y-coordinate of upper-left corner of source rectangle
int nWidthSrc, // width of source rectangle
int nHeightSrc, // height of source rectangle
DWORD dwRop // raster operation code
);
Y a peut-être exemples intrinsèques sur site dédié à VB (j'ai pas l'URL en tête, Cf chercher sur le forum...).