bitfilt.h File Reference

(r1785/r1771)

#include "bmpprefs.h"
#include "bmpsrc.h"
#include "filtimop.h"

Go to the source code of this file.

Classes
class	BitmapImportOptions
	Base class for storing import options It's not actually used much though... More...
class	BaseBitmapFilter
	Base class for bitmap filters. (Currently export only). Inherited classes tend to be in the OIL layer. The base class fails on both imports & exports, so you only need to override the half that you implement. More...
Functions
INT32	GridLock (INT32 Position, INT32 GridSize)
	Grid-locks a given plotting position to lie over a grid (usually the output device-pixel grid). The result is shifted by half the grid size to grid-lock to the _center_ of a pixel rather than the edges. Note: stolen from ColourEditDlg/PreviewDialog rendering routines Hoisted into header file, since useful for anything that uses bitmaps.

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Function Documentation

INT32 GridLock (  INT32  Position, INT32  GridSize )  [inline]

Grid-locks a given plotting position to lie over a grid (usually the output device-pixel grid). The result is shifted by half the grid size to grid-lock to the _center_ of a pixel rather than the edges. Note: stolen from ColourEditDlg/PreviewDialog rendering routines Hoisted into header file, since useful for anything that uses bitmaps. Author: Neville_Humphrys (Xara Group Ltd) <camelotdev@xara.com> from Jason code in coldlog.cpp Date: 22/9/97 Parameters: Position  - The X/Y position, in millipoints [INPUTS] GridSize - the size of the grid to lock to, in millipoints Returns: Position, locked (by rounding) to a grid of the given size, and offset by half a grid. Definition at line 541 of file bitfilt.h. { // By truncating down to the nearest grid point, and adding half the grid value, // we achieve rounding to the nearest offset-grid position. // NOTE: // The original algorithm incorrectly rounded negative numbers towards // zero. Negative numbers should be rounded towards negative infinity. // The algorithm has been corrected by always rounding a positive number // and restoring the original sign of the number after rounding. BOOL bNegative = FALSE; // Assume the number is positive if (Position < 0) // If the number if not positive { // note the fact and make positive bNegative = TRUE; Position = -Position; } Position += GridSize / 2; Position -= Position % GridSize; if (bNegative) // If the number was negative Position = -Position; // restore the sign return (Position); }

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