SDLine

SDLine is a preclipped line rendering routine. It processes line operations onto a destination linear address. SDLine is the default when OS2_PM_DRV_ENABLE: QueryDeviceSurface does not hook the pfnLine function directly.

Syntax

SDLine(pInput, pOutput);

Parameters

pInput (PLINEINFO) - input

Pointer to LINEINFO data structure.

ulLength

Length of the LINEINFO data structure.

ulType

Defines line type.

LINE_SOLID : Line will be solid in Foreground color.

LINE_INVISIBLE : Line is not drawn.

LINE_ALTERNATE : Line will be alternating Foreground and Background color; ignores style.

ulStyleMask

A 32-bit style mask.

cLines

Count of lines to be drawn.

ulFGColor

Line Foreground color.

ulBGColor

Line Background color.

usForeROP

Line Foreground mix.

usBackROP

Line Background mix.

pDstBmapInfo

Destination surface (BMAPINFO).

alpkLinePack

Array of line details information.

ulStyleStep : The value to be added to ulStyleValue on each pel stepped along the line style's direction.

ulStyleValue The style value at the current pel. It is composed of an error value and a mask position, as follows:

┌───────────────┬───────────────┬───────────────┬───────────────┐
│high word      │3 bits         │5 bits         │8 bits         │
├───────────────┼───────────────┼───────────────┼───────────────┤
│not used       │not used       │mask pos       │error value    │
└───────────────┴───────────────┴───────────────┴───────────────┘

ulFlags Miscellaneous flags used for the LINEPACK data structure.

LINE_DO_FIRST_PEL Draws the first pel.

LINE_DIR_Y_POSITIVE Indicates line direction is bottom-to-top.

LINE_HORIZONTAL Indicates line is horizontal. No Bresenham algorithm.

LINE_X_MAJOR Line is XMAJOR.

LINE_DIR_X_POSITIVE Indicates line direction is right-to-left.

LINE_VERTICAL Indicates line is vertical. No Bresenham algorithm.

LINE_STYLE_X_MAJOR Line style is XMAJOR.

LINE_DO_LAST_PEL Draws the last pel.

ulAbsDeltaX

Clipped Bresenham Delta X, absolute (ptlStart.x - ptlEnd.x).

ulAbsDeltaY

Clipped Bresenham Delta Y, absolute (ptlStart.y - ptlEnd.y).

ptlClipStart

Pointer to location where device performs the Bresenham algorithm. Sets only the pels from ptlClipStart to ptlClipEnd, inclusive.

ptlClipEnd

Ending location for Bresenham algorithm (see previous parameter, ptlClipStart).

ptlStart

Pointer to starting location for line. The device can perform the Bresenham algorithm from ptlStart or ptlClipStart.

ptlEnd

Ending location for line.

lClipStartError

The standard Bresenham error at the clipped start point. This error is calculated from the initial error at the start point and the error increments for major step and diagonal step. The initial error and the error increments are as follows:

MAX

Maximum (ulAbsDeltaX, ulAbsDeltaY)

MIN

Minimum (ulAbsDeltaX, ulAbsDeltaY)

Major Increment

Increment to the error for stepping along the major axis: 2 * MIN.

Diagonal Increment

Increment to the error for stepping along the major and minor axes: 2 * MIN - 2 * MAX.

Initial Error

Error at the start point: 2 * MIN - MAX, if LINE_DIR_X_POSITIVE is On

2 * MIN - MAX - 1, if LINE_DIR_Y_POSITIVE is Off.

Horizontal and vertical lines. The line is drawn from the clipped start to clipped end. The lClipStartError will not be given.

First pel consideration. Set the first pel at the ptlStart (not ptlClipStart) only if LINE_DO_FIRST_PEL is set and the first pel is not clipped.

Last pel consideration. Set the last pel at the ptlEnd (not ptlClipEnd) only if LINE_DO_LAST_PEL is set and the last pel is not clipped.

Styling. Lines are styled using the ulStyleMask, ulStyleStep and ulStyleValue.

Error Value

Error value at the current pel.

Mask Position

Bit position of the ulStyleMask.

If this bit is on, set the current pel to the ulFGColor through usForeROP; otherwise, set the current pel to the ulBGColor through usBackROP.

prclBounds

Bounding rect of the clipped line.

pOutput (PVOID) - input

Reserved.

Returns

rc (ULONG) - returns

Return codes.

Valid values are:

RC_SUCCESS   
RC_ERROR   

Remarks

Simulation support: This function is simulated by a handling routine in Revision 2.X of the graphics engine.

Example Code

#include <os2.h>

PLINEINFO    pInput;   /*  Pointer to LINEINFO data structure. */
PVOID        pOutput;  /*  Reserved. */
ULONG        rc;       /*  Return codes. */

rc = SDLine(pInput, pOutput);

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