EngPlgBlt function (winddi.h)

Article
10/13/2021

The EngPlgBlt function causes GDI to perform a rotate bit-block transfer.

Syntax

ENGAPI BOOL EngPlgBlt(
       SURFOBJ         *psoTrg,
       SURFOBJ         *psoSrc,
       SURFOBJ         *psoMsk,
       CLIPOBJ         *pco,
       XLATEOBJ        *pxlo,
       COLORADJUSTMENT *pca,
       POINTL          *pptlBrushOrg,
       POINTFIX        *pptfx,
       RECTL           *prcl,
       POINTL          *pptl,
  [in] ULONG           iMode
);

Parameters

psoTrg

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 operation.

psoMsk

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

This mask limits the area of the source that is copied. A mask has an implicit rop4 of 0xCCAA, which means the source should be copied wherever the mask is 1, but the destination should be left alone wherever the mask is zero.

If this parameter is NULL, there is an implicit rop4 of 0xCCCC, which means the source should be copied everywhere in the source rectangle.

The mask will always be large enough to contain the relevant source; tiling is unnecessary.

pco

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

Whenever possible, GDI simplifies the clipping involved. Unlike the DrvBitBlt function, EngPlgBlt may be called with a single clipping rectangle. This prevents rounding errors in clipping the output.

pxlo

Pointer to a XLATEOBJ structure that defines how color indices are translated between the source and target surfaces. This XLATEOBJ structure can be queried to find the RGB color for any source index.

A high quality rotate bit-block transfer is needed to interpolate colors.

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 Microsoft Windows SDK documentation.

pptlBrushOrg

Pointer to a POINTL structure that specifies 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.

pptfx

Pointer to three POINTFIX structures that define a parallelogram in the destination surface. A fourth, implicit, vertex is given as: D = B + C − A. For a description of this data type, see GDI Data Types.

EngPlgBlt is never called with A, B, and C collinear.

prcl

Pointer to a RECTL structure that defines, in the coordinate system of the source surface, the area to be copied. The points of the source rectangle are well ordered. EngPlgBlt will never be given an empty source rectangle.

pptl

Pointer to a POINTL structure that specifies which pixel in the given mask corresponds to the upper-left pixel in the source rectangle. Ignore this parameter if psoMsk is NULL.

[in] iMode

Defines how source pixels are combined to get output pixels. This parameter can be one of the following values:

Value	Meaning
BLACKONWHITE	On a shrinking bit-block transfer, pixels should be combined with an 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 need not be combined. On a stretching bit-block transfer, pixels should be replicated.
HALFTONE	The driver may 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 an OR operation. On a stretching block transfers, pixels should be replicated.

The methods WHITEONBLACK, BLACKONWHITE, and COLORONCOLOR are simple and provide compatibility for old applications, but do not produce the best looking results for color surfaces.

Return value

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

Remarks

EngPlgBlt performs only certain types of rotations.

This function performs bit-block transfers from a rectangle defined by prcl to any parallelogram. The parallelogram is defined by pptfx, which points to an array of three points.

The source rectangle at prcl is considered to be a geometric rectangle whose corners are displaced by (-0.5,-0.5) from the given integer coordinates. This exactly matches the source rectangle for EngStretchBlt. The source rectangle is always well ordered.

The upper-left corner of the source rectangle is mapped to the first point, A. The upper-right corner of the source rectangle is mapped to the second point, B. The lower-left corner of the source rectangle is mapped to the third point, C. The lower-right corner of the source rectangle is mapped to the implicit point in the parallelogram defined by treating the three given points as vectors and computing:

D = B + C - A

Note that a stretch blit can be expressed exactly as a parallelogram blit, but the coordinates given for the destination will be divisible by five.

Requirements

Requirement	Value
Minimum supported client	Available in Windows 2000 and later versions of the Windows operating systems.
Target Platform	Universal
Header	winddi.h (include Winddi.h)
Library	Win32k.lib
DLL	Win32k.sys