EngStretchBlt

The EngStretchBlt function causes GDI to do a stretching bit-block transfer.

BOOL
  EngStretchBlt(
    IN SURFOBJ  *psoDest,
    IN SURFOBJ  *psoSrc,
    IN SURFOBJ  *psoMask,
    IN CLIPOBJ  *pco,
    IN XLATEOBJ  *pxlo,
    IN COLORADJUSTMENT  *pca,
    IN POINTL  pptlHTOrg,
    IN RECTL  *prclDest,
    IN RECTL  *prclSrc,
    IN POINTL  *pptlMask,
    IN ULONG  iMode
    );

Parameters

psoDest

Pointer to a SURFOBJ structure that describes the surface on which to draw.

psoSrc

Pointer to a SURFOBJ structure that describes the source surface for the bit-block transfer.

psoMask

Pointer to a SURFOBJ structure that defines a mask for the source. The mask is defined by a logic map, which is a bitmap with one bit per pixel.

The mask limits the area of the source that is copied. If this parameter is specified, it has an implicit rop4 of 0xCCAA, meaning the source should be copied wherever the mask is 1, but the destination should be left alone wherever the mask is 0.

If this parameter is null, the rop4 is implicitly 0xCCCC, which means the source should be copied everywhere in the source rectangle.

pco

Pointer to a CLIPOBJ structure that limits the area to be modified in the destination. GDI services are provided to enumerate the clip region as a set of rectangles.

Whenever possible, GDI simplifies the clipping involved. However, unlike DrvBitBlt, EngStretchBlt can be called with a single clipping rectangle. This prevents rounding errors in clipping the output.

pxlo

Pointer to a XLATEOBJ structure that specifies how color indices are to be translated between the source and target surfaces.

This XLATEOBJ structure can also be queried to find the RGB color for any source index. A high quality stretching bit-block transfer will need to interpolate colors in some cases.

pca

Pointer to a COLORADJUSTMENT structure that defines the color adjustment values to be applied to the source bitmap before stretching the bits. For more information see the Platform SDK documentation.

pptlHTOrg

Pointer to a POINTL structure that defines the origin of the halftone brush. Drivers that use halftone brushes should align the upper left pixel of the brush's pattern with this point on the device surface.

prclDest

Pointer to a RECTL structure that defines the area to be modified in the coordinate system of the destination surface. This rectangle is defined by two points that are not well ordered, meaning the coordinates of the second point are not necessarily larger than those of the first point. The rectangle described does not include the lower and right edges. This function is never called with an empty destination rectangle.

If the destination rectangle is not well ordered, EngStretchBlt makes it well ordered.

prclSrc

Pointer to a RECTL structure that defines the area to be copied, in the coordinate system of the source surface. The rectangle will map to the rectangle defined by prclDest. This function is never given an empty source rectangle, and the points of the source rectangle are always well-ordered.

The mapping is defined by prclSrc and prclDest. The points specified in prclDest and prclSrc lie on integer coordinates, which correspond to pixel centers. A rectangle defined by two such points is considered to be a geometric rectangle with two vertices whose coordinates are the given points, but with 0.5 subtracted from each coordinate. (POINTL structures are shorthand notation for specifying these fractional coordinate vertices.)

The edges of any rectangle never intersect a pixel, but go around a set of pixels. The pixels that are inside the rectangle are those expected for a bottom-right exclusive rectangle. EngStretchBlt maps the geometric source rectangle exactly onto the geometric destination rectangle.

pptlMask

Pointer to a POINTL structure that defines the pixel in the given mask that corresponds to the upper left pixel in the source rectangle. This parameter is ignored if no mask is specified.

iMode

Specifies how source pixels are combined to get output pixels. The HALFTONE mode is slower than the other modes, but produces higher quality images.

Value	Meaning
BLACKONWHITE	On a shrinking bit-block transfer, pixels should be combined with a Boolean AND operation. On a stretching bit-block transfer, pixels should be replicated.
COLORONCOLOR	On a shrinking bit-block transfer, enough pixels should be ignored so that pixels don't need to be combined. On a stretching bit-block transfer, pixels should be replicated.
HALFTONE	The driver can use groups of pixels in the output surface to best approximate the color or gray level of the input.
WHITEONBLACK	On a shrinking bit-block transfer, pixels should be combined with a Boolean OR operation. On a stretching bit-block transfer, pixels should be replicated.

Return Value

The return value is TRUE if the function is successful. Otherwise, it is FALSE and an error code is reported.

Headers

Declared in winddi.h. Include winddi.h.

Comments

This function allows the same halftoning algorithm to be applied to GDI bitmaps and device surfaces.

The driver should call EngStretchBlt if it has hooked DrvStretchBlt and is called to do something the driver does not support.

See Also

CLIPOBJ, DrvBitBlt, DrvStretchBlt, SURFOBJ, XLATEOBJ