LineDDA

← →
__Alx___ (2002-11-16 11:49) [0]

LineDDA
Platform SDK: Windows GDI
LineDDA
The LineDDA function determines which pixels should be highlighted for a line defined by the specified starting and ending points.

BOOL LineDDA(
int nXStart, // x-coordinate of starting point
int nYStart, // y-coordinate of starting point
int nXEnd, // x-coordinate of ending point
int nYEnd, // y-coordinate of ending point
LINEDDAPROC lpLineFunc, // callback function
LPARAM lpData // application-defined data
);
Parameters
nXStart
[in] Specifies the x-coordinate of the line"s starting point.
nYStart
[in] Specifies the y-coordinate of the line"s starting point.
nXEnd
[in] Specifies the x-coordinate of the line"s ending point.
nYEnd
[in] Specifies the y-coordinate of the line"s ending point.
lpLineFunc
[in] Pointer to an application-defined callback function. For more information, see the LineDDAProc callback function.
lpData
[in] Pointer to the application-defined data.
Return Values
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Windows NT/2000: To get extended error information, call GetLastError.

Remarks
The LineDDA function passes the coordinates for each point along the line, except for the line"s ending point, to the application-defined callback function. In addition to passing the coordinates of a point, this function passes any existing application-defined data.

The coordinates passed to the callback function match pixels on a video display only if the default transformations and mapping modes are used.

Requirements
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in Wingdi.h; include Windows.h.
Library: Use Gdi32.lib.

See Also
Lines and Curves Overview, Line and Curve Functions, LineDDAProc

Built on Wednesday, February 09, 2000Requirements
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in Wingdi.h; include Windows.h.
Library: Use Gdi32.lib.
See Also
Lines and Curves Overview, Line and Curve Functions, LineDDAProc

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Что есть LPARAM lpData ??
In addition to passing the coordinates of a point, this function passes any existing application-defined data.
т.е application-defined data??

← →
MBo (2002-11-16 12:12) [1]

свои дополнительные данные для рисования - какие угодно.
Например, можно передавать указатель на ImageList и для каждой точки выбирать из него картинку

← →
__Alx___ (2002-11-16 12:15) [2]

Чуть чуть подробней
А если у меня толко координаты линии ? ТОгда передавать 0?

← →
MBo (2002-11-16 12:17) [3]

если ничего не нужно, то и не передавай - 0 или nil

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