paint: add drawing program from 9front (#112)

Paint first appeared in 9front. The 9front license is reproduced
in the related source files - the original repository is located at
https://code.9front.org/hg/plan9front.

3 files changed, 1128 insertions, 0 deletions

diff --git a/src/cmd/paint/eenter.c b/src/cmd/paint/eenter.c
new file mode 100644
index 00000000..6645820c
--- /dev/null
+++ b/src/cmd/paint/eenter.c
@@ -0,0 +1,258 @@
+/*
+This code was taken from 9front repository (https://code.9front.org/hg/plan9front).
+It is subject to license from 9front, below is a reproduction of the license.
+
+Copyright (c) 20XX 9front
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <event.h>
+#include <keyboard.h>
+
+/* additional keyboard codes needed - defined here to avoid API change */
+enum {
+	Spec=   0xF800,
+	Knack=  0x15,
+	Ksoh=   0x01,
+	Kenq=   0x05,
+	Ketb=   0x17
+};
+
+int
+eenter(char *ask, char *buf, int len, Mouse *m)
+{
+	int done, down, tick, n, h, w, l, i;
+	Image *b, *save, *backcol, *bordcol;
+	Point p, o, t;
+	Rectangle r, sc;
+	Event ev;
+	Rune k;
+
+	o = screen->r.min;
+	backcol = allocimagemix(display, DPurpleblue, DWhite);
+	bordcol = allocimage(display, Rect(0,0,1,1), screen->chan, 1, DPurpleblue);
+	if(backcol == nil || bordcol == nil)
+		return -1;
+
+	while(ecankbd())
+		ekbd();
+
+	if(m) o = m->xy;
+
+	if(buf && len > 0)
+		n = strlen(buf);
+	else {
+		buf = nil;
+		len = 0;
+		n = 0;
+	}
+
+	k = -1;
+	tick = n;
+	save = nil;
+	done = down = 0;
+
+	p = stringsize(font, " ");
+	h = p.y;
+	w = p.x;
+
+	b = screen;
+	sc = b->clipr;
+	replclipr(b, 0, b->r);
+
+	while(!done){
+		p = stringsize(font, buf ? buf : "");
+		if(ask && ask[0]){
+			if(buf) p.x += w;
+			p.x += stringwidth(font, ask);
+		}
+		r = rectaddpt(insetrect(Rpt(ZP, p), -4), o);
+		p.x = 0;
+		r = rectsubpt(r, p);
+
+		p = ZP;
+		if(r.min.x < screen->r.min.x)
+			p.x = screen->r.min.x - r.min.x;
+		if(r.min.y < screen->r.min.y)
+			p.y = screen->r.min.y - r.min.y;
+		r = rectaddpt(r, p);
+		p = ZP;
+		if(r.max.x > screen->r.max.x)
+			p.x = r.max.x - screen->r.max.x;
+		if(r.max.y > screen->r.max.y)
+			p.y = r.max.y - screen->r.max.y;
+		r = rectsubpt(r, p);
+
+		r = insetrect(r, -2);
+		if(save == nil){
+			save = allocimage(display, r, b->chan, 0, DNofill);
+			if(save == nil){
+				n = -1;
+				break;
+			}
+			draw(save, r, b, nil, r.min);
+		}
+		draw(b, r, backcol, nil, ZP);
+		border(b, r, 2, bordcol, ZP);
+		p = addpt(r.min, Pt(6, 6));
+		if(ask && ask[0]){
+			p = string(b, p, bordcol, ZP, font, ask);
+			if(buf) p.x += w;
+		}
+		if(buf){
+			t = p;
+			p = stringn(b, p, display->black, ZP, font, buf, utfnlen(buf, tick));
+			draw(b, Rect(p.x-1, p.y, p.x+2, p.y+3), display->black, nil, ZP);
+			draw(b, Rect(p.x, p.y, p.x+1, p.y+h), display->black, nil, ZP);
+			draw(b, Rect(p.x-1, p.y+h-3, p.x+2, p.y+h), display->black, nil, ZP);
+			p = string(b, p, display->black, ZP, font, buf+tick);
+		}
+		flushimage(display, 1);
+
+nodraw:
+		i = Ekeyboard;
+		if(m != nil)
+			i |= Emouse;
+
+		replclipr(b, 0, sc);
+		i = eread(i, &ev);
+
+		/* screen might have been resized */
+		if(b != screen || !eqrect(screen->clipr, sc)){
+			freeimage(save);
+			save = nil;
+		}
+		b = screen;
+		sc = b->clipr;
+		replclipr(b, 0, b->r);
+
+		switch(i){
+		default:
+			done = 1;
+			n = -1;
+			break;
+		case Ekeyboard:
+			k = ev.kbdc;
+			if(buf == nil || k == Keof || k == '\n'){
+				done = 1;
+				break;
+			}
+			if(k == Knack || k == Kesc){
+				done = !n;
+				buf[n = tick = 0] = 0;
+				break;
+			}
+			if(k == Ksoh || k == Khome){
+				tick = 0;
+				continue;
+			}
+			if(k == Kenq || k == Kend){
+				tick = n;
+				continue;
+			}
+			if(k == Kright){
+				if(tick < n)
+					tick += chartorune(&k, buf+tick);
+				continue;
+			}
+			if(k == Kleft){
+				for(i = 0; i < n; i += l){
+					l = chartorune(&k, buf+tick);
+					if(i+l >= tick){
+						tick = i;
+						break;
+					}
+				}
+				continue;
+			}
+			if(k == Ketb){
+				while(tick > 0){
+					tick--;
+					if(tick == 0 ||
+					   strchr(" !\"#$%&'()*+,-./:;<=>?@`[\\]^{|}~", buf[tick-1]))
+						break;
+				}
+				buf[n = tick] = 0;
+				break;
+			}
+			if(k == Kbs){
+				if(tick <= 0)
+					continue;
+				for(i = 0; i < n; i += l){
+					l = chartorune(&k, buf+i);
+					if(i+l >= tick){
+						memmove(buf+i, buf+i+l, n - (i+l));
+						buf[n -= l] = 0;
+						tick -= l;
+						break;
+					}
+				}
+				break;
+			}
+			if(k < 0x20 || k == Kdel || (k & 0xFF00) == KF || (k & 0xFF00) == Spec)
+				continue;
+			if((len-n) <= (l = runelen(k)))
+				continue;
+			memmove(buf+tick+l, buf+tick, n - tick);
+			runetochar(buf+tick, &k);
+			buf[n += l] = 0;
+			tick += l;
+			break;
+		case Emouse:
+			*m = ev.mouse;
+			if(!ptinrect(m->xy, r)){
+				down = 0;
+				goto nodraw;
+			}
+			if(m->buttons & 7){
+				down = 1;
+				if(buf && m->xy.x >= (t.x - w)){
+					down = 0;
+					for(i = 0; i < n; i += l){
+						l = chartorune(&k, buf+i);
+						t.x += stringnwidth(font, buf+i, 1);
+						if(t.x > m->xy.x)
+							break;
+					}
+					tick = i;
+				}
+				continue;
+			}
+			done = down;
+			break;
+		}
+		if(save){
+			draw(b, save->r, save, nil, save->r.min);
+			freeimage(save);
+			save = nil;
+		}
+	}
+
+	replclipr(b, 0, sc);
+
+	freeimage(backcol);
+	freeimage(bordcol);
+	flushimage(display, 1);
+
+	return n;
+}
+
diff --git a/src/cmd/paint/mkfile b/src/cmd/paint/mkfile
new file mode 100644
index 00000000..272db4b4
--- /dev/null
+++ b/src/cmd/paint/mkfile
@@ -0,0 +1,11 @@
+<$PLAN9/src/mkhdr
+
+TARG=paint
+
+OFILES=\
+	eenter.$O\
+	paint.$O\
+
+HFILES=paint.h\
+
+<$PLAN9/src/mkone
diff --git a/src/cmd/paint/paint.c b/src/cmd/paint/paint.c
new file mode 100644
index 00000000..7dce3710
--- /dev/null
+++ b/src/cmd/paint/paint.c
@@ -0,0 +1,859 @@
+/*
+This code was taken from 9front repository (https://code.9front.org/hg/plan9front).
+It is subject to license from 9front, below is a reproduction of the license.
+
+Copyright (c) 20XX 9front
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <event.h>
+#include <keyboard.h>
+
+/* additional libdraw function needed - defined here to avoid API change */
+extern int             eenter(char*, char*, int, Mouse*);
+
+char *filename;
+int zoom = 1;
+int brush = 1;
+Point spos;		/* position on screen */
+Point cpos;		/* position on canvas */
+Image *canvas;
+Image *ink;
+Image *back;
+Image *pal[16];		/* palette */
+Rectangle palr;		/* palette rect on screen */
+Rectangle penr;		/* pen size rect on screen */
+
+enum {
+	NBRUSH = 10+1,
+};
+
+int nundo = 0;
+Image *undo[1024];
+
+int c64[] = {		/* c64 color palette */
+	0x000000,
+	0xFFFFFF,
+	0x68372B,
+	0x70A4B2,
+	0x6F3D86,
+	0x588D43,
+	0x352879,
+	0xB8C76F,
+	0x6F4F25,
+	0x433900,
+	0x9A6759,
+	0x444444,
+	0x6C6C6C,
+	0x9AD284,
+	0x6C5EB5,
+	0x959595,
+};
+
+/*
+ * get bounding rectnagle for stroke from r.min to r.max with
+ * specified brush (size).
+ */
+static Rectangle
+strokerect(Rectangle r, int brush)
+{
+	r = canonrect(r);
+	return Rect(r.min.x-brush, r.min.y-brush, r.max.x+brush+1, r.max.y+brush+1);
+}
+
+/*
+ * draw stroke from r.min to r.max to dst with color ink and
+ * brush (size).
+ */
+static void
+strokedraw(Image *dst, Rectangle r, Image *ink, int brush)
+{
+	if(!eqpt(r.min, r.max))
+		line(dst, r.min, r.max, Enddisc, Enddisc, brush, ink, ZP);
+	fillellipse(dst, r.max, brush, brush, ink, ZP);
+}
+
+/*
+ * A draw operation that touches only the area contained in bot but not in top.
+ * mp and sp get aligned with bot.min.
+ */
+static void
+gendrawdiff(Image *dst, Rectangle bot, Rectangle top, 
+	Image *src, Point sp, Image *mask, Point mp, int op)
+{
+	Rectangle r;
+	Point origin;
+	Point delta;
+
+	if(Dx(bot)*Dy(bot) == 0)
+		return;
+
+	/* no points in bot - top */
+	if(rectinrect(bot, top))
+		return;
+
+	/* bot - top ≡ bot */
+	if(Dx(top)*Dy(top)==0 || rectXrect(bot, top)==0){
+		gendrawop(dst, bot, src, sp, mask, mp, op);
+		return;
+	}
+
+	origin = bot.min;
+	/* split bot into rectangles that don't intersect top */
+	/* left side */
+	if(bot.min.x < top.min.x){
+		r = Rect(bot.min.x, bot.min.y, top.min.x, bot.max.y);
+		delta = subpt(r.min, origin);
+		gendrawop(dst, r, src, addpt(sp, delta), mask, addpt(mp, delta), op);
+		bot.min.x = top.min.x;
+	}
+
+	/* right side */
+	if(bot.max.x > top.max.x){
+		r = Rect(top.max.x, bot.min.y, bot.max.x, bot.max.y);
+		delta = subpt(r.min, origin);
+		gendrawop(dst, r, src, addpt(sp, delta), mask, addpt(mp, delta), op);
+		bot.max.x = top.max.x;
+	}
+
+	/* top */
+	if(bot.min.y < top.min.y){
+		r = Rect(bot.min.x, bot.min.y, bot.max.x, top.min.y);
+		delta = subpt(r.min, origin);
+		gendrawop(dst, r, src, addpt(sp, delta), mask, addpt(mp, delta), op);
+		bot.min.y = top.min.y;
+	}
+
+	/* bottom */
+	if(bot.max.y > top.max.y){
+		r = Rect(bot.min.x, top.max.y, bot.max.x, bot.max.y);
+		delta = subpt(r.min, origin);
+		gendrawop(dst, r, src, addpt(sp, delta), mask, addpt(mp, delta), op);
+		bot.max.y = top.max.y;
+	}
+}
+
+int
+alphachan(ulong chan)
+{
+	for(; chan; chan >>= 8)
+		if(TYPE(chan) == CAlpha)
+			return 1;
+	return 0;
+}
+
+void
+zoomdraw(Image *d, Rectangle r, Rectangle top, Image *b, Image *s, Point sp, int f)
+{
+	Rectangle dr;
+	Image *t;
+	Point a;
+	int w;
+
+	a = ZP;
+	if(r.min.x < d->r.min.x){
+		sp.x += (d->r.min.x - r.min.x)/f;
+		a.x = (d->r.min.x - r.min.x)%f;
+		r.min.x = d->r.min.x;
+	}
+	if(r.min.y < d->r.min.y){
+		sp.y += (d->r.min.y - r.min.y)/f;
+		a.y = (d->r.min.y - r.min.y)%f;
+		r.min.y = d->r.min.y;
+	}
+	rectclip(&r, d->r);
+	w = s->r.max.x - sp.x;
+	if(w > Dx(r))
+		w = Dx(r);
+	dr = r;
+	dr.max.x = dr.min.x+w;
+	if(!alphachan(s->chan))
+		b = nil;
+	if(f <= 1){
+		if(b) gendrawdiff(d, dr, top, b, sp, nil, ZP, SoverD);
+		gendrawdiff(d, dr, top, s, sp, nil, ZP, SoverD);
+		return;
+	}
+	if((t = allocimage(display, dr, s->chan, 0, 0)) == nil)
+		return;
+	for(; dr.min.y < r.max.y; dr.min.y++){
+		dr.max.y = dr.min.y+1;
+		draw(t, dr, s, nil, sp);
+		if(++a.y == f){
+			a.y = 0;
+			sp.y++;
+		}
+	}
+	dr = r;
+	for(sp=dr.min; dr.min.x < r.max.x; sp.x++){
+		dr.max.x = dr.min.x+1;
+		if(b) gendrawdiff(d, dr, top, b, sp, nil, ZP, SoverD);
+		gendrawdiff(d, dr, top, t, sp, nil, ZP, SoverD);
+		for(dr.min.x++; ++a.x < f && dr.min.x < r.max.x; dr.min.x++){
+			dr.max.x = dr.min.x+1;
+			gendrawdiff(d, dr, top, d, Pt(dr.min.x-1, dr.min.y), nil, ZP, SoverD);
+		}
+		a.x = 0;
+	}
+	freeimage(t);
+}
+
+Point
+s2c(Point p){
+	p = subpt(p, spos);
+	if(p.x < 0) p.x -= zoom-1;
+	if(p.y < 0) p.y -= zoom-1;
+	return addpt(divpt(p, zoom), cpos);
+}
+
+Point
+c2s(Point p){
+	return addpt(mulpt(subpt(p, cpos), zoom), spos);
+}
+
+Rectangle
+c2sr(Rectangle r){
+	return Rpt(c2s(r.min), c2s(r.max));
+}
+
+void
+update(Rectangle *rp){
+	if(canvas==nil)
+		draw(screen, screen->r, back, nil, ZP);
+	else {
+		if(rp == nil)
+			rp = &canvas->r;
+		gendrawdiff(screen, screen->r, c2sr(canvas->r), back, ZP, nil, ZP, SoverD);
+		zoomdraw(screen, c2sr(*rp), ZR, back, canvas, rp->min, zoom);
+	}
+	flushimage(display, 1);
+}
+
+void
+expand(Rectangle r)
+{
+	Rectangle nr;
+	Image *tmp;
+
+	if(canvas==nil){
+		if((canvas = allocimage(display, r, screen->chan, 0, DNofill)) == nil)
+			sysfatal("allocimage: %r");
+		draw(canvas, canvas->r, back, nil, ZP);
+		return;
+	}
+	nr = canvas->r;
+	combinerect(&nr, r);
+	if(eqrect(nr, canvas->r))
+		return;
+	if((tmp = allocimage(display, nr, canvas->chan, 0, DNofill)) == nil)
+		return;
+	draw(tmp, canvas->r, canvas, nil, canvas->r.min);
+	gendrawdiff(tmp, tmp->r, canvas->r, back, ZP, nil, ZP, SoverD);
+	freeimage(canvas);
+	canvas = tmp;
+}
+
+void
+save(Rectangle r, int mark)
+{
+	Image *tmp;
+	int x;
+
+	if(mark){
+		x = nundo++ % nelem(undo);
+		if(undo[x])
+			freeimage(undo[x]);
+		undo[x] = nil;
+	}
+	if(canvas==nil || nundo<0)
+		return;
+	if(!rectclip(&r, canvas->r))
+		return;
+	if((tmp = allocimage(display, r, canvas->chan, 0, DNofill)) == nil)
+		return;
+	draw(tmp, r, canvas, nil, r.min);
+	x = nundo++ % nelem(undo);
+	if(undo[x])
+		freeimage(undo[x]);
+	undo[x] = tmp;
+}
+
+void
+restore(int n)
+{
+	Image *tmp;
+	int x;
+
+	while(nundo > 0){
+		if(n-- == 0)
+			return;
+		x = --nundo % nelem(undo);
+		if((tmp = undo[x]) == nil)
+			return;
+		undo[x] = nil;
+		if(canvas == nil || canvas->chan != tmp->chan){
+			freeimage(canvas);
+			canvas = tmp;
+			update(nil);
+		} else {
+			expand(tmp->r);
+			draw(canvas, tmp->r, tmp, nil, tmp->r.min);
+			update(&tmp->r);
+			freeimage(tmp);
+		}
+	}
+}
+
+typedef struct {
+	Rectangle	r;
+	Rectangle	r0;
+	Image*		dst;
+
+	int		yscan;	/* current scanline */
+	int		wscan;	/* bscan width in bytes */
+	Image*		iscan;	/* scanline image */
+	uchar*		bscan;	/* scanline buffer */
+
+	int		nmask;	/* size of bmask in bytes */
+	int		wmask;	/* width of bmask in bytes */
+	Image*		imask;	/* mask image */
+	uchar*		bmask;	/* mask buffer */
+
+	int		ncmp;
+	uchar		bcmp[4];
+} Filldata;
+
+void
+fillscan(Filldata *f, Point p0)
+{
+	int x, y;
+	uchar *b;
+
+	x = p0.x;
+	y = p0.y;
+	b = f->bmask + y*f->wmask;
+	if(b[x/8] & 0x80>>(x%8))
+		return;
+
+	if(f->yscan != y){
+		draw(f->iscan, f->iscan->r, f->dst, nil, Pt(f->r.min.x, f->r.min.y+y));
+		if(unloadimage(f->iscan, f->iscan->r, f->bscan, f->wscan) < 0)
+			return;
+		f->yscan = y;
+	}
+
+	for(x = p0.x; x >= 0; x--){
+		if(memcmp(f->bscan + x*f->ncmp, f->bcmp, f->ncmp))
+			break;
+		b[x/8] |= 0x80>>(x%8);
+	}
+	for(x = p0.x+1; x < f->r0.max.x; x++){
+		if(memcmp(f->bscan + x*f->ncmp, f->bcmp, f->ncmp))
+			break;
+		b[x/8] |= 0x80>>(x%8);
+	}
+
+	y = p0.y-1;
+	if(y >= 0){
+		for(x = p0.x; x >= 0; x--){
+			if((b[x/8] & 0x80>>(x%8)) == 0)
+				break;
+			fillscan(f, Pt(x, y));
+		}
+		for(x = p0.x+1; x < f->r0.max.x; x++){
+			if((b[x/8] & 0x80>>(x%8)) == 0)
+				break;
+			fillscan(f, Pt(x, y));
+		}
+	}
+
+	y = p0.y+1;
+	if(y < f->r0.max.y){
+		for(x = p0.x; x >= 0; x--){
+			if((b[x/8] & 0x80>>(x%8)) == 0)
+				break;
+			fillscan(f, Pt(x, y));
+		}
+		for(x = p0.x+1; x < f->r0.max.x; x++){
+			if((b[x/8] & 0x80>>(x%8)) == 0)
+				break;
+			fillscan(f, Pt(x, y));
+		}
+	}
+}
+
+void
+floodfill(Image *dst, Rectangle r, Point p, Image *src)
+{
+	Filldata f;
+
+	if(!rectclip(&r, dst->r))
+		return;
+	if(!ptinrect(p, r))
+		return;
+	memset(&f, 0, sizeof(f));
+	f.dst = dst;
+	f.r = r;
+	f.r0 = rectsubpt(r, r.min);
+	f.wmask = bytesperline(f.r0, 1);
+	f.nmask = f.wmask*f.r0.max.y;
+	if((f.bmask = mallocz(f.nmask, 1)) == nil)
+		goto out;
+	if((f.imask = allocimage(display, f.r0, GREY1, 0, DNofill)) == nil)
+		goto out;
+
+	r = f.r0;
+	r.max.y = 1;
+	if((f.iscan = allocimage(display, r, RGB24, 0, DNofill)) == nil)
+		goto out;
+	f.yscan = -1;
+	f.wscan = bytesperline(f.iscan->r, f.iscan->depth);
+	if((f.bscan = mallocz(f.wscan, 0)) == nil)
+		goto out;
+
+	r = Rect(0,0,1,1);
+	f.ncmp = (f.iscan->depth+7) / 8;
+	draw(f.iscan, r, dst, nil, p);
+	if(unloadimage(f.iscan, r, f.bcmp, sizeof(f.bcmp)) < 0)
+		goto out;
+
+	fillscan(&f, subpt(p, f.r.min));
+
+	loadimage(f.imask, f.imask->r, f.bmask, f.nmask);
+	draw(f.dst, f.r, src, f.imask, f.imask->r.min);
+out:
+	free(f.bmask);
+	free(f.bscan);
+	if(f.iscan)
+		freeimage(f.iscan);
+	if(f.imask)
+		freeimage(f.imask);
+}
+
+void
+translate(Point d)
+{
+	Rectangle r, nr;
+
+	if(canvas==nil || d.x==0 && d.y==0)
+		return;
+	r = c2sr(canvas->r);
+	nr = rectaddpt(r, d);
+	rectclip(&r, screen->clipr);
+	draw(screen, rectaddpt(r, d), screen, nil, r.min);
+	zoomdraw(screen, nr, rectaddpt(r, d), back, canvas, canvas->r.min, zoom);
+	gendrawdiff(screen, screen->r, nr, back, ZP, nil, ZP, SoverD);
+	spos = addpt(spos, d);
+	flushimage(display, 1);
+}
+
+void
+setzoom(Point o, int z)
+{
+	if(z < 1)
+		return;
+	cpos = s2c(o);
+	spos = o;
+	zoom = z;
+	update(nil);
+}
+
+void
+center(void)
+{
+	cpos = ZP;
+	if(canvas)
+		cpos = addpt(canvas->r.min, 
+			divpt(subpt(canvas->r.max, canvas->r.min), 2));
+	spos = addpt(screen->r.min,
+		divpt(subpt(screen->r.max, screen->r.min), 2));
+	update(nil);
+}
+
+void
+drawpal(void)
+{
+	Rectangle r, rr;
+	int i;
+
+	r = screen->r;
+	r.min.y = r.max.y - 20;
+	replclipr(screen, 0, r);
+
+	penr = r;
+	penr.min.x = r.max.x - NBRUSH*Dy(r);
+
+	palr = r;
+	palr.max.x = penr.min.x;
+
+	r = penr;
+	draw(screen, r, back, nil, ZP);
+	for(i=0; i<NBRUSH; i++){
+		r.max.x = penr.min.x + (i+1)*Dx(penr) / NBRUSH;
+		rr = r;
+		if(i == brush)
+			rr.min.y += Dy(r)/3;
+		if(i == NBRUSH-1){
+			/* last is special brush for fill draw */
+			draw(screen, rr, ink, nil, ZP);
+		} else {
+			rr.min = addpt(rr.min, divpt(subpt(rr.max, rr.min), 2));
+			rr.max = rr.min;
+			strokedraw(screen, rr, ink, i);
+		}
+		r.min.x = r.max.x;
+	}
+
+	r = palr;
+	for(i=1; i<=nelem(pal); i++){
+		r.max.x = palr.min.x + i*Dx(palr) / nelem(pal);
+		rr = r;
+		if(ink == pal[i-1])
+			rr.min.y += Dy(r)/3;
+		draw(screen, rr, pal[i-1], nil, ZP);
+		gendrawdiff(screen, r, rr, back, ZP, nil, ZP, SoverD);
+		r.min.x = r.max.x;
+	}
+
+	r = screen->r;
+	r.max.y -= Dy(palr);
+	replclipr(screen, 0, r);
+}
+
+int
+hitpal(Mouse m)
+{
+	if(ptinrect(m.xy, penr)){
+		if(m.buttons & 7){
+			brush = ((m.xy.x - penr.min.x) * NBRUSH) / Dx(penr);
+			drawpal();
+		}
+		return 1;
+	}
+	if(ptinrect(m.xy, palr)){
+		Image *col;
+
+		col = pal[(m.xy.x - palr.min.x) * nelem(pal) / Dx(palr)];
+		switch(m.buttons & 7){
+		case 1:
+			ink = col;
+			drawpal();
+			break;
+		case 2:
+			back = col;
+			drawpal();
+			update(nil);
+			break;
+		}
+		return 1;
+	}
+	return 0;
+}
+
+void
+catch(void * _, char *msg)
+{
+	USED(_);
+	if(strstr(msg, "closed pipe"))
+		noted(NCONT);
+	noted(NDFLT);
+}
+
+int
+pipeline(char *fmt, ...)
+{
+	char buf[1024];
+	va_list a;
+	int p[2];
+
+	va_start(a, fmt);
+	vsnprint(buf, sizeof(buf), fmt, a);
+	va_end(a);
+	if(pipe(p) < 0)
+		return -1;
+	switch(rfork(RFPROC|RFMEM|RFFDG|RFNOTEG)){ // RFEND not available in libc port
+	case -1:
+		close(p[0]);
+		close(p[1]);
+		return -1;
+	case 0:
+		close(p[1]);
+		dup(p[0], 0);
+		dup(p[0], 1);
+		close(p[0]);
+		execl("/bin/rc", "rc", "-c", buf, nil);
+		exits("exec");
+	}
+	close(p[0]);
+	return p[1];
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s [ file ]\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	char *s, buf[1024];
+	Rectangle r;
+	Image *img;
+	int i, fd;
+	Event e;
+	Mouse m;
+	Point p, d;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if(argc == 1)
+		filename = strdup(argv[0]);
+	else if(argc != 0)
+		usage();	
+
+	if(initdraw(0, 0, "paint") < 0)
+		sysfatal("initdraw: %r");
+
+	if(filename){
+		if((fd = open(filename, OREAD)) < 0)
+			sysfatal("open: %r");
+		if((canvas = readimage(display, fd, 0)) == nil)
+			sysfatal("readimage: %r");
+		close(fd);
+	}
+
+	/* palette initialization */
+	for(i=0; i<nelem(pal); i++){
+		pal[i] = allocimage(display, Rect(0, 0, 1, 1), RGB24, 1,
+			c64[i % nelem(c64)]<<8 | 0xFF);
+		if(pal[i] == nil)
+			sysfatal("allocimage: %r");
+	}
+	ink = pal[0];
+	back = pal[1];
+	drawpal();
+	center();
+
+	einit(Emouse | Ekeyboard);
+
+	notify(catch);
+	for(;;) {
+		switch(event(&e)){
+		case Emouse:
+			if(hitpal(e.mouse))
+				continue;
+
+			img = ink;
+			switch(e.mouse.buttons & 7){
+			case 2:
+				img = back;
+				/* no break */
+			case 1:
+				p = s2c(e.mouse.xy);
+				if(brush == NBRUSH-1){
+					/* flood fill brush */
+					if(canvas == nil || !ptinrect(p, canvas->r)){
+						back = img;
+						drawpal();
+						update(nil);
+						break;
+					}
+					r = canvas->r;
+					save(r, 1);
+					floodfill(canvas, r, p, img);
+					update(&r);
+
+					/* wait for mouse release */
+					while(event(&e) == Emouse && (e.mouse.buttons & 7) != 0)
+						;
+					break;
+				}
+				r = strokerect(Rpt(p, p), brush);
+				expand(r);
+				save(r, 1);
+				strokedraw(canvas, Rpt(p, p), img, brush);
+				update(&r);
+				for(;;){
+					m = e.mouse;
+					if(event(&e) != Emouse)
+						break;
+					if((e.mouse.buttons ^ m.buttons) & 7)
+						break;
+					d = s2c(e.mouse.xy);
+					if(eqpt(d, p))
+						continue;
+					r = strokerect(Rpt(p, d), brush);
+					expand(r);
+					save(r, 0);
+					strokedraw(canvas, Rpt(p, d), img, brush);
+					update(&r);
+					p = d;
+				}
+				break;
+			case 4:
+				for(;;){
+					m = e.mouse;
+					if(event(&e) != Emouse)
+						break;
+					if((e.mouse.buttons & 7) != 4)
+						break;
+					translate(subpt(e.mouse.xy, m.xy));
+				}
+				break;
+			}
+			break;
+		case Ekeyboard:
+			switch(e.kbdc){
+			case Kesc:
+				zoom = 1;
+				center();
+				break;
+			case '+':
+				if(zoom < 0x1000)
+					setzoom(e.mouse.xy, zoom*2);
+				break;
+			case '-':
+				if(zoom > 1)
+					setzoom(e.mouse.xy, zoom/2);
+				break;
+			case 'c':
+				if(canvas == nil)
+					break;
+				save(canvas->r, 1);
+				freeimage(canvas);
+				canvas = nil;
+				update(nil);
+				break;
+			case 'u':
+				restore(16);
+				break;
+			case 'f':
+				brush = NBRUSH-1;
+				drawpal();
+				break;
+			case '0': case '1': case '2': case '3': case '4':
+			case '5': case '6': case '7': case '8': case '9':
+				brush = e.kbdc - '0';
+				drawpal();
+				break;
+			default:
+				if(e.kbdc == Kdel)
+					e.kbdc = 'q';
+				buf[0] = 0;
+				if(filename && (e.kbdc == 'r' || e.kbdc == 'w'))
+					snprint(buf, sizeof(buf), "%C %s", e.kbdc, filename);
+				else if(e.kbdc > 0x20 && e.kbdc < 0x7f)
+					snprint(buf, sizeof(buf), "%C", e.kbdc);
+				if(eenter("Cmd", buf, sizeof(buf), &e.mouse) <= 0)
+					break;
+				if(strcmp(buf, "q") == 0)
+					exits(nil);
+				s = buf+1;
+				while(*s == ' ' || *s == '\t')
+					s++;
+				if(*s == 0)
+					break;
+				switch(buf[0]){
+				case 'r':
+					if((fd = open(s, OREAD)) < 0){
+					Error:
+						snprint(buf, sizeof(buf), "%r");
+						eenter(buf, nil, 0, &e.mouse);
+						break;
+					}
+					free(filename);
+					filename = strdup(s);
+				Readimage:
+					unlockdisplay(display);
+					img = readimage(display, fd, 1);
+					close(fd);
+					lockdisplay(display);
+					if(img == nil){
+						werrstr("readimage: %r");
+						goto Error;
+					}
+					if(canvas){
+						save(canvas->r, 1);
+						freeimage(canvas);
+					}
+					canvas = img;
+					center();
+					break;
+				case 'w':
+					if((fd = create(s, OWRITE, 0660)) < 0)
+						goto Error;
+					free(filename);
+					filename = strdup(s);
+				Writeimage:
+					if(canvas)
+					if(writeimage(fd, canvas, 0) < 0){
+						close(fd);
+						werrstr("writeimage: %r");
+						goto Error;
+					}
+					close(fd);
+					break;
+				case '<':
+					if((fd = pipeline("%s", s)) < 0)
+						goto Error;
+					goto Readimage;
+				case '>':
+					if((fd = pipeline("%s", s)) < 0)
+						goto Error;
+					goto Writeimage;
+				case '|':
+					if(canvas == nil)
+						break;
+					if((fd = pipeline("%s", s)) < 0)
+						goto Error;
+					switch(rfork(RFMEM|RFPROC|RFFDG)){
+					case -1:
+						close(fd);
+						werrstr("rfork: %r");
+						goto Error;
+					case 0:
+						writeimage(fd, canvas, 1);
+						exits(nil);
+					}
+					goto Readimage;
+				}
+				break;
+			}
+			break;
+		}
+	}
+}
+
+void
+eresized(int _)
+{
+	USED(_);
+	if(getwindow(display, Refnone) < 0)
+		sysfatal("resize failed");
+	drawpal();
+	update(nil);
+}