frinit, frsetrects, frclear, frcharofpt, frptofchar, frinsert, frdelete, frselect, frse-
lectp, frselectf, frgetmouse - frames of text
void frinit(Frame *f, Rectangle r, Font *ft, Bitmap *b);
void frsetrects(Frame *f, Rectangle r, Bitmap *b);
void frclear(Frame *f);
ulong frcharofpt(Frame *f, Point pt);
Point frptofchar(Frame *f, ulong p);
void frinsert(Frame *f, Rune *r0, Rune *r1, ulong p);
int frdelete(Frame *f, ulong p0, ulong p1);
void frselect(Frame *f, Mouse *m);
void frselectp(Frame *f, Fcode fc);
void frselectf(Frame *f, Point p0, Point p1, Fcode c);
extern void frgetmouse(void);
This library supports frames of editable text in a single font on bitmap displays, such as
in sam(1) and 81/2(1). Frames may hold any character except NUL (0). Long lines are
folded and tabs are at fixed intervals.
The user-visible data structure, a Frame, is defined in <frame.h>:
typedef struct Frame Frame;
Font *font; /* of chars in the frame */
Bitmap *b; /* on which frame appears */
Rectangle r; /* in which text appears */
Rectangle entire; /* of full frame */
ulong p0, p1; /* selection */
short left; /* left edge of text */
ushort nbox, nalloc;
ushort maxtab; /* max size of tab,in pixels */
ushort nchars; /* # runes in frame */
ushort nlines; /* # lines with text */
ushort maxlines; /* total # lines in frame */
ushort lastlinefull; /* last line fills frame */
ushort modified; /* changed since frselect() */
Frbox is an internal type and is not used by the interface. P0 and p1 may be changed by
the application provided the selection routines are called afterwards to maintain a con-
sistent display. Maxtab determines the size of tab stops. Frinit sets it to 8 times the
width of a 0 (zero) character in the font; it may be changed before any text is added to
the frame. The other elements of the structure are maintained by the library and should
not be modified directly.
The text within frames is not directly addressable; instead frames are designed to work
alongside another structure that holds the text. The typical application is to display a
section of a longer document such as a text file or terminal session. Usually the appli-
cation will keep its own copy of the text in the window (probably as an array of Runes)
and pass components of this text to the frame routines to display the visible portion.
Only the text that is visible is held by the Frame; the application must check maxlines,
nlines, and lastlinefull to determine, for example, whether new text needs to be appended
at the end of the Frame after calling frdelete (q.v.).
There are no routines in the library to allocate Frames; instead the interface assumes
that Frames will be components of larger structures. Frinit prepares the Frame f so char-
acters drawn in it will appear in the single Font ft. It then calls frsetrects to ini-
tialize the geometry for the Frame. The Bitmap b is where the Frame is to be drawn; Rec-
tangle r defines the limit of the portion of the Bitmap the text will occupy. The Bitmap
pointer may be null, allowing the other routines to be called to maintain the associated
data structure in, for example, an obscured window.
Frclear frees the internal structures associated with f, permitting another frinit or
frsetrects on the Frame. If f is to be deallocated, the associated Font and Bitmap must
be freed separately.
To reshape a Frame, use frclear and frinit and then frinsert (q.v.) to recreate the dis-
play. If a Frame is being moved but not reshaped, that is, if the shape of its containing
rectangle is unchanged, it is sufficient to bitblt(2) the containing rectangle from the
old to the new location and then call frsetrects to establish the new geometry. No
redrawing is necessary.
Frames hold text as runes, not as bytes. Frptofchar returns the location of the upper
left corner of the p'th rune, starting from 0, in the Frame f. If f holds fewer than p
runes, frptofchar returns the location of the upper right corner of the last character in
f. Frcharofpt is the inverse: it returns the index of the closest rune whose image's
upper left corner is up and to the left of pt.
Frinsert inserts into Frame f starting at rune index p the runes between r0 and r1. If a
NUL (0) character is inserted, chaos will ensue. Tabs and newlines are handled by the
library, but all other characters, including control characters, are just displayed. For
example, backspaces are printed; to erase a character, use frdelete.
Frdelete deletes from the Frame the text between p0 and p1; p1 points at the first rune
beyond the deletion.
Frselect tracks the mouse to select a contiguous string of text in the Frame. When
called, a mouse button is typically down. Frselect will return when the button state has
changed (some buttons may still be down) and will set f->p0 and f->p1 to the selected
range of text. Frselectf and frselectp modify the display of the selected text. Frse-
lectf highlights the text between p0 and p1 (which must have been returned by frptofchar)
using bitblt in mode c. Frselectp is similar but highlights the text from f->p0 to f->p1.
Neither frselectf nor frselectp modifies f->p0 or f->p1.
Upon return from frinsert or frdelete, the display will be consistent but f->p0 and f->p1
may not point to the desired selection. It may be necessary to adjust the selection and
use frselectf or frselectp to fix the display.
Frgetmouse must be provided by the application; frselect calls it to get mouse updates.
Each call to frgetmouse should update the Mouse structure pointed to by frselect's argu-
ment m. Frgetmouse should block until the mouse status has changed.
graphics(2), bitblt(2), cachechars(2).