term% cat index.txt FRAME(2) System Calls Manual FRAME(2)
NAME
frinit, frsetrects, frinittick, frclear, frcharofpt, frptofchar, frin‐
sert, frdelete, frselect, frtick, frselectpaint, frdrawsel, frdrawsel0,
frgetmouse - frames of text
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <draw.h>
#include <thread.h>
#include <mouse.h>
#include <frame.h>
void frinit(Frame *f, Rectangle r, Font *ft, Image *b, Image **cols)
void frsetrects(Frame *f, Rectangle r, Image *b)
void frinittick(Frame *f)
void frclear(Frame *f, int resize)
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, Mousectl *m)
void frtick(Frame *f, Point pt, int up)
void frselectpaint(Frame *f, Point p0, Point p1, Image *col)
void frdrawsel(Frame *f, Point pt0, ulong p0, ulong p1,
int highlighted)
void frdrawsel0(Frame *f, Point pt0, ulong p0, ulong p1,
Image *back, Image *text)
enum{
BACK,
HIGH,
BORD,
TEXT,
HTEXT,
NCOL
};
DESCRIPTION
This library supports frames of editable text in a single font on
raster displays, such as in sam(1) and rio(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 */
Display *display; /* on which frame appears */
Image *b; /* on which frame appears */
Image *cols[NCOL]; /* text and background colors */
Rectangle r; /* in which text appears */
Rectangle entire; /* of full frame */
Frbox *box;
ulong p0, p1; /* selection */
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() */
Image *tick; /* typing tick */
Image *tickback; /* saved image under tick */
int ticked; /* flag: is tick onscreen? */
};
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 consistent 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 program 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 visi‐
ble 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 characters drawn in it will appear in
the single Font ft. It then calls frsetrects and frinittick to ini‐
tialize the geometry for the Frame. The Image b is where the Frame is
to be drawn; Rectangle r defines the limit of the portion of the Image
the text will occupy. The Image pointer may be null, allowing the
other routines to be called to maintain the associated data structure
in, for example, an obscured window.
The array of Images cols sets the colors in which text and borders will
be drawn. The background of the frame will be drawn in cols[BACK]; the
background of highlighted text in cols[HIGH]; borders and scroll bar in
cols[BORD]; regular text in cols[TEXT]; and highlighted text in
cols[HTEXT].
Frclear frees the internal structures associated with f, permitting an‐
other frinit or frsetrects on the Frame. It does not clear the associ‐
ated display. If f is to be deallocated, the associated Font and Image
must be freed separately. The resize argument should be non-zero if
the frame is to be redrawn with a different font; otherwise the frame
will maintain some data structures associated with the font.
To resize a Frame, use frclear and frinit and then frinsert (q.v.) to
recreate the display. If a Frame is being moved but not resized, that
is, if the shape of its containing rectangle is unchanged, it is suffi‐
cient to use draw(2) to copy the containing rectangle from the old to
the new location and then call frsetrects to establish the new geome‐
try. (It is unnecessary to call frinittick unless the font size has
changed.) No redrawing is necessary.
Frames hold text as runes, not as bytes. Frptofchar returns the loca‐
tion 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 loca‐
tion 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 be‐
tween 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.
Programs that wish to manage the selection themselves have several rou‐
tines to help. They involve the maintenance of the `tick', the verti‐
cal line indicating a null selection between characters, and the col‐
ored region representing a non-null selection. Frtick draws (if up is
non-zero) or removes (if up is zero) the tick at the screen position
indicated by pt. Frdrawsel repaints a section of the frame, delimited
by character positions p0 and p1, either with plain background or en‐
tirely highlighted, according to the flag highlighted, managing the
tick appropriately. The point pt0 is the geometrical location of p0 on
the screen; like all of the selection-helper routines' Point arguments,
it must be a value generated by frptofchar. Frdrawsel0 is a lower-
level routine, taking as arguments a background color, back, and text
color, text. It assumes that the tick is being handled (removed be‐
forehand, replaced afterwards, as required) by its caller. Frselect‐
paint uses a solid color, col, to paint a region of the frame defined
by the Points p0 and p1.
SOURCE
/sys/src/libframe
SEE ALSO
graphics(2), draw(2), cachechars(2).
FRAME(2)