FRAME(2) FRAME(2)
NAME
frinit, frsetrects, frclear, frcharofpt, frptofchar,
frinsert, frdelete, frselect, frselectp, frselectf,
frgetmouse - frames of text
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <libg.h>
#include <frame.h>
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);
DESCRIPTION
This library supports frames of editable text in a single
font on bitmap displays, such as in sam(1) and 8½(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;
struct 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 */
Frbox *box;
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FRAME(2) FRAME(2)
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 main-
tained 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 application 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 dis-
play 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 initialize the geometry for the
Frame. The Bitmap b is where the Frame is to be drawn;
Rectangle 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 win-
dow.
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 display. If a Frame is being moved
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FRAME(2) FRAME(2)
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 charac-
ters, 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.
Frselectf 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
argument m. Frgetmouse should block until the mouse status
has changed.
SOURCE
/sys/src/libframe
SEE ALSO
graphics(2), bitblt(2), cachechars(2).
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