The 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. The system stretches or compresses the bitmap according to the stretching mode currently set in the destination device context.

BOOL StretchBlt(
  HDC hdcDest,      // handle to destination DC
  int nXOriginDest, // x-coord of destination upper-left corner
  int nYOriginDest, // y-coord of destination upper-left corner
  int nWidthDest,   // width of destination rectangle
  int nHeightDest,  // height of destination rectangle
  HDC hdcSrc,       // handle to source DC
  int nXOriginSrc,  // x-coord of source upper-left corner
  int nYOriginSrc,  // y-coord of source upper-left corner
  int nWidthSrc,    // width of source rectangle
  int nHeightSrc,   // height of source rectangle
  DWORD dwRop       // raster operation code
);

Parameters

hdcDest

[in] Handle to the destination device context.

nXOriginDest

[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle.

nYOriginDest

[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle.

nWidthDest

[in] Specifies the width, in logical units, of the destination rectangle.

nHeightDest

[in] Specifies the height, in logical units, of the destination rectangle.

hdcSrc

[in] Handle to the source device context.

nXOriginSrc

[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle.

nYOriginSrc

[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle.

nWidthSrc

[in] Specifies the width, in logical units, of the source rectangle.

nHeightSrc

[in] Specifies the height, in logical units, of the source rectangle.

dwRop

[in] Specifies the raster operation to be performed. Raster operation codes define how the system combines colors in output operations that involve a brush, a source bitmap, and a destination bitmap.

See BitBlt for a list of common raster operation codes (ROPs). Note that the CAPTUREBLT ROP generally cannot be used for printing device contexts.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Remarks

StretchBlt stretches or compresses the source bitmap in memory and then copies the result to the destination rectangle. This bitmap can be either a compatible bitmap (DDB) or the output from CreateDIBSection. The color data for pattern or destination pixels is merged after the stretching or compression occurs.

When an enhanced metafile is being recorded, an error occurs (and the function returns FALSE) if the source device context identifies an enhanced-metafile device context.

If the specified raster operation requires a brush, the system uses the brush currently selected into the destination device context.

The destination coordinates are transformed by using the transformation currently specified for the destination device context; the source coordinates are transformed by using the transformation currently specified for the source device context.

If the source transformation has a rotation or shear, an error occurs.

If destination, source, and pattern bitmaps do not have the same color format, StretchBlt converts the source and pattern bitmaps to match the destination bitmap.

If StretchBlt must convert a monochrome bitmap to a color bitmap, it sets white bits (1) to the background color and black bits (0) to the foreground color. To convert a color bitmap to a monochrome bitmap, it sets pixels that match the background color to white (1) and sets all other pixels to black (0). The foreground and background colors of the device context with color are used.

StretchBlt creates a mirror image of a bitmap if the signs of the nWidthSrc and nWidthDest parameters or if the nHeightSrc and nHeightDest parameters differ. If nWidthSrc and nWidthDest have different signs, the function creates a mirror image of the bitmap along the x-axis. If nHeightSrc and nHeightDest have different signs, the function creates a mirror image of the bitmap along the y-axis.

Not all devices support the StretchBlt function. For more information, see the GetDeviceCaps.

ICM: No color management is performed when a blit operation occurs.

Windows 98/Me, Windows 2000/XP: When used in a multiple monitor system, both hdcSrc and hdcDest must refer to the same device or the function will fail. To transfer data between DCs for different devices, convert the memory bitmap to a DIB by calling GetDIBits. To display the DIB to the second device, call SetDIBits or StretchDIBits.

Example Code

For an example, see Scaling an Image.

Requirements

  Windows NT/2000/XP/Vista: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.
  Header: Declared in Wingdi.h; include Windows.h.
  Library: Use Gdi32.lib.

See Also

Bitmaps Overview, Bitmap Functions, BitBlt, CreateDIBSection, GetDeviceCaps, GetDIBits, MaskBlt, PlgBlt, SetDIBits, SetStretchBltMode , StretchDIBits