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NAME
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frinit, frsetrects, frinittick, frclear, frcharofpt, frptofchar,
frinsert, frdelete, frselect, frtick, frselectpaint, frdrawsel,
frdrawsel0, frgetmouse – frames of text
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SYNOPSIS
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#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,
void frdrawsel0(Frame *f, Point pt0, ulong p0, ulong p1,
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Image *back, Image *text)
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enum{
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BACK,
HIGH,
BORD,
TEXT,
HTEXT,
NCOL
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};
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DESCRIPTION
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This library supports frames of editable text in a single font
on raster displays, such as in sam(1) and 9term(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>:
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typedef struct Frame Frame;
struct Frame
{
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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? */
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};
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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 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 characters drawn in
it will appear in the single Font ft. It then calls frsetrects
and frinittick to initialize 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
another frinit or frsetrects on the Frame. It does not clear the
associated 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 sufficient to use draw(3) to copy the containing rectangle
from the old to the new location and then call frsetrects to establish
the new geometry. (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
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.
Programs that wish to manage the selection themselves have several
routines to help. They involve the maintenance of the ‘tick’,
the vertical line indicating a null selection between characters,
and the colored 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 entirely
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 beforehand, replaced afterwards,
as required) by its caller. Frselectpaint uses a solid color,
col, to paint a region of the frame defined by the Points p0 and
p1.
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SOURCE
SEE ALSO
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