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NPixel2Char

Find the nearest character offset

#include <Script.h> Script Manager

short NPixel2Char(textBuf, textLen, slop, pixelWidth, leadingEdge,

widthRemaining, styleRunPosition, numer, denom );

Ptr textBuf ; address of a text buffer

long textLen ; value for text length

Fixed slop ; value indicating extra pixels

Fixed pixelWidth ; indicates the width of a character

Boolean *leadingEdge ; indicates the beginning of the character

Fixed * widthRemaining ; amount of excess width

JustStyleCode styleRunPosition ; the position of a style run within the line

Point numer ; scaling factor

Point denom ; scaling factor

The NPixel2Char function helps you find the nearest character offset

within a text buffer corresponding to a given pixel width. It returns an integer

that is the offset of the character closest to pixelWidth. It is the inverse of the

NChar2Pixel function.

textBuf is a text buffer indicated by a pointer.

textLen is the length of the buffer.

slop is the number of pixels to add to a string's width after it has been

scaled.

pixelWidth indicates the width of a character.

leadingEdge TRUE if the offset is on the leading edge of the character.

widthRemaining :ÍE

amount of excess width. If the pixelWidth parameter that is passed

into NPixel2Char is greater than the width of the text specified by

the textBuf and textLen parameters, the amount of excess width is

returned in the widthRemaining parameter; otherwise,

widthRemaining is set to -1.

styleRunPosition For correct spacing between multiple style runs, you can specify

the position of a style run within the line by using the

styleRunPosition parameter of type JustStyleCode. See below for a

list of the values and meanings for these constants.

numer is a scaling factor

denom is a scaling factor

Returns: a short, indicating the offset of the character PixelWidth is closest

to.

Notes: The most common application of NPixel2Char is identifying the

character where a mouse-down event occurs in text and whether it is on the

leading or trailing edge of the character. For correct spacing between

multiple style runs, you can specify the position of a style run within the

line by using the styleRunPosition parameter of type JustStyleCode.

To handle the spacing between multiple style runs on a line correctly, the

new justification routines take a styleRunPosition parameter that specifies

the position of the style run on a line.

The values for styleRunPosition are as follows:

Constant Meaning

smOnlyStyleRun This style run is the only one on the line.

smLeftStyleRun Multiple style runs are on the line, and this is the

leftmost.

smRightStyleRun Multiple style runs are on the line, and this is the

rightmost.

smMiddleStyleRun Multiple style runs are on the line, and this is

neither the leftmost nor the rightmost.

If styleRunPosition has the value smOnlyStyleRun, the justification

routines behave exactly like their earlier versions. For other values of

styleRunPosition, the behavior may depend on the script. The behavior for

Roman is in Justifying Text on the Roman Script System.

Note: In the NMeasureJust, NChar2Pixel, and NPixel2Char

routines, the text length should equal the entire visible part of the

style run on a line and should include trailing spaces if and only if

they are displayed. (They may not be displayed for the last style run

in the line, for example.) Otherwise, the results for the last

character on the line may be in valid.

Referenced by (11):