StretchBlt function (wingdi.h)

Article
10/13/2021

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.

Syntax

BOOL StretchBlt(
  [in] HDC   hdcDest,
  [in] int   xDest,
  [in] int   yDest,
  [in] int   wDest,
  [in] int   hDest,
  [in] HDC   hdcSrc,
  [in] int   xSrc,
  [in] int   ySrc,
  [in] int   wSrc,
  [in] int   hSrc,
  [in] DWORD rop
);

Parameters

[in] hdcDest

A handle to the destination device context.

[in] xDest

The x-coordinate, in logical units, of the upper-left corner of the destination rectangle.

[in] yDest

The y-coordinate, in logical units, of the upper-left corner of the destination rectangle.

[in] wDest

The width, in logical units, of the destination rectangle.

[in] hDest

The height, in logical units, of the destination rectangle.

[in] hdcSrc

A handle to the source device context.

[in] xSrc

The x-coordinate, in logical units, of the upper-left corner of the source rectangle.

[in] ySrc

The y-coordinate, in logical units, of the upper-left corner of the source rectangle.

[in] wSrc

The width, in logical units, of the source rectangle.

[in] hSrc

The height, in logical units, of the source rectangle.

[in] rop

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 value

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.

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.

Examples

For an example, see Scaling an Image.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	wingdi.h (include Windows.h)
Library	Gdi32.lib
DLL	Gdi32.dll

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