=> R0 = initial font handle, or 0 for current
R1 = pointer to string
R2 = flags
R3,4 = (x,y) of mouse click, or max w,h of string
R5 = pointer to block holding spacing, split & bounding box
R6 = pointer to transformation matrix
R7 = length of string
<= R1 = pointer to where the scan ended
R3,4 = (x,y) of where the scan ended
R7 = number of split chars in scanned part of string.
This SWI is used to find various info on a string :
· How wide is a string?
Use large values for R3, R4 and no split character
· Given a width, how much of a string will fit?
AND · Address of a mouse click?
Use correct width in R3, large value in R4 and (if needed) a split char in the buffer at R5
· Graphical position of a caret?
Set R7 to offset into string, use huge values for R3,4, and no split
Registers 0,5,6 and 7 are only used if bits 8,5,6 and 7 are set in R2
If bit 8 of R2 is clear then the current font will be assumed. This call does not alter current font, so if you are scanning several sequential lines, and these can contain font shifts, you should call Font_FutureFont to find which font handle to pass in R0 the next time.
If bit 20 of R2 is set but there is no split character, then R7 will be used to return the number of non-control characters (codes 32 or greater and not within a control sequence)
Unlike Font_Paint, this call only allows millipoints for all coordinates. Convert to/from OS units by dividing/multiplying by 400. (Instead of dividing, you can multiply by (1<<18 / 400) and then shift down 18 to get an approximate answer)
See PRM 3, page 483.
Font_ScanString flags
Bit Meaning if set
0-4 0 (reserved)
5 R5 is pointer to block
6 R6 is pointer to transformation matrix
7 R7 is length of string
8 R0 is initial font handle
9 perform kerning
10 writing direction is Right to Left
11 0 (reserved)
12 R1 points to 16-bit string (bit 13 must be clear) (FontManager 3.41+)
13 R1 points to 32-bit string (bit 12 must be clear) (FontManager 3.41+)
14-16 0 (Reserved)
17 return nearest caret position (If x offset is less than half way through a char, we don't include this char)
18 return bounding box in R5 (bit 5 must also be set)
19 return updated matrix in R6 (bit 6 must also be set)
20 return number of split chars in R7 (bit 7 must also be set)
21-31 0 (reserved)
Font_ScanString block
Offset Contents
0 additional x offset for spaces
4 additional y offset for spaces
8 additional x offset for each letter
12 additional y offset for each letter
16 split character (or -1 for none)
20 returns left of bounding box (if b18 set)
24 returns bottom of bounding box (if b18 set)
28 returns right of bounding box (if b18 set)
32 returns top of bounding box (if b18 set)
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