frutil.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <draw.h>
#include <thread.h>
#include <mouse.h>
#include <frame.h>

int
_frcanfit(Frame *f, Point pt, Frbox *b)
{
	int left, w, nr;
	uchar *p;
	Rune r;

	left = f->r.max.x-pt.x;
	if(b->nrune < 0)
		return b->minwid <= left;
	if(left >= b->wid)
		return b->nrune;
	for(nr=0,p=b->ptr; *p; p+=w,nr++){
		r = *p;
		if(r < Runeself)
			w = 1;
		else
			w = chartorune(&r, (char*)p);
		left -= stringnwidth(f->font, (char*)p, 1);
		if(left < 0)
			return nr;
	}
	drawerror(f->display, "_frcanfit can't");
	return 0;
}

void
_frcklinewrap(Frame *f, Point *p, Frbox *b)
{
	if((b->nrune<0? b->minwid : b->wid) > f->r.max.x-p->x){
		p->x = f->r.min.x;
		p->y += f->font->height;
	}
}

void
_frcklinewrap0(Frame *f, Point *p, Frbox *b)
{
	if(_frcanfit(f, *p, b) == 0){
		p->x = f->r.min.x;
		p->y += f->font->height;
	}
}

void
_fradvance(Frame *f, Point *p, Frbox *b)
{
	if(b->nrune<0 && b->bc=='\n'){
		p->x = f->r.min.x;
		p->y += f->font->height;
	}else
		p->x += b->wid;
}

int
_frnewwid(Frame *f, Point pt, Frbox *b)
{
	b->wid = _frnewwid0(f, pt, b);
	return b->wid;
}

int
_frnewwid0(Frame *f, Point pt, Frbox *b)
{
	int c, x;

	c = f->r.max.x;
	x = pt.x;
	if(b->nrune>=0 || b->bc!='\t')
		return b->wid;
	if(x+b->minwid > c)
		x = pt.x = f->r.min.x;
	x += f->maxtab;
	x -= (x-f->r.min.x)%f->maxtab;
	if(x-pt.x<b->minwid || x>c)
		x = pt.x+b->minwid;
	return x-pt.x;
}

void
_frclean(Frame *f, Point pt, int n0, int n1)	/* look for mergeable boxes */
{
	Frbox *b;
	int nb, c;

	c = f->r.max.x;
	for(nb=n0; nb<n1-1; nb++){
		b = &f->box[nb];
		_frcklinewrap(f, &pt, b);
		while(b[0].nrune>=0 && nb<n1-1 && b[1].nrune>=0 && pt.x+b[0].wid+b[1].wid<c){
			_frmergebox(f, nb);
			n1--;
			b = &f->box[nb];
		}
		_fradvance(f, &pt, &f->box[nb]);
	}
	for(; nb<f->nbox; nb++){
		b = &f->box[nb];
		_frcklinewrap(f, &pt, b);
		_fradvance(f, &pt, &f->box[nb]);
	}
	f->lastlinefull = 0;
	if(pt.y >= f->r.max.y)
		f->lastlinefull = 1;
}