## Presentation Device Driver Reference for OS/2

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### LINEPACK Field - lClipStartError

lClipStartError (LONG) Standard Bresenham error at the clipped start point.

Error is calculated from the initial error 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_X_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 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 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.
ulStyleMask A 32-bit style mask.

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.