GreSetStyleRatio

GreSetStyleRatio sets the style ratio used by the presentation driver's line-drawing algorithm to determine which pels are turned ON to draw a sloping line.

Simulation support: This function is mandatory for display drivers. For other drivers, it is simulated by a handling routine in the graphics engine.

Syntax

GreSetStyleRatio(hdc, pRatio, pInstance, lFunction);

Parameters

hdc (HDC) - input: The device context handle.

pRatio (PBYTE) - input: Pointer to two unsigned bytes corresponding to the aspect of the pels on which a line is drawn. The style ratio is defined as a two-byte value. The low-order byte indicates a step in the X-direction, and the high-order byte a step in the Y-direction. Typical values for style ratios are:

For EGA devices, X-direction equals 64 and Y-direction equals 85.
For one-to-one devices, X-direction equals 64 and Y-direction equals 64. In this case, the style ratio steps are set to 64:64 rather than 1:1 to ensure that a single dot in a line-style pattern is a sensible length. The length of a single dot in the pattern is (256/step_value) pels.

pInstance (PVOID) - input: A pointer to instance data.

lFunction (ULONG) - input: High-order WORD=flags; low-order WORD=NGreSetStyleRatio.

Return Code

fSuccess (BOOL) - returns: Return codes.

On completion, the handling routine must return BOOLEAN (fSuccess).

TRUE Successful
FALSE Error

Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. Error codes for conditions that the handling routine is expected to check include:

PMERR_DEV_FUNC_NOT_INSTALLED
PMERR_INV_HDC

Remarks

Display drivers must support this function so that a hardcopy driver (whose device can have a different style ratio) can use the display driver to draw into a bit map that the hardcopy driver can use.

Declaration

#define INCL_GRE_DEVMISC2
#include <os2.h>

HDC      hdc;        /*  The device context handle. */
PBYTE    pRatio;
PVOID    pInstance;  /*  A pointer to instance data. */
ULONG    lFunction;  /*  High-order WORD=flags; low-order WORD=NGreSetStyleRatio. */
BOOL     fSuccess;   /*  Return codes. */

fSuccess = GreSetStyleRatio(hdc, pRatio, pInstance,
             lFunction);