#include <event.h>

#include <u.h>
#include <libc.h>
#include <draw.h>
#include <event.h>
#include <keyboard.h>

enum {
Edge = 5,
Maxmag = 16
};

enum {
Mzoom,
Munzoom,
Mgrid,
Mredraw,
Mexit
};

char *menustr[] = {
"zoom",
"unzoom",
"grid",
"redraw",
"exit",
nil
};

Menu menu = {
menustr,
nil,
-1
};

Point lastp;
Image *red;
Image *tmp;
Image *grid;
Image *chequer;
int screenfd;
int mag = 4;
int showgrid = 0;
Rectangle screenr;
uchar *screenbuf;

void magnify(void);
void makegrid(void);

void
drawit(void)
{
Rectangle r;
border(screen, screen->r, Edge, red, ZP);
magnify();
r = insetrect(screen->r, Edge);
draw(screen, r, tmp, nil, tmp->r.min);
flushimage(display, 1);
}

int bypp;

void
main(int argc, char *argv[])
{
Event e;
char buf[5*12];
ulong chan;
int d;

USED(argc, argv);
if(initdraw(nil, nil, "lens") < 0){
fprint(2, "lens: initdraw failed: %r\n");
exits("initdraw");
}
einit(Emouse|Ekeyboard);
red = allocimage(display, Rect(0, 0, 1, 1), CMAP8, 1, DRed);
chequer = allocimage(display, Rect(0, 0, 2, 2), GREY1, 1, DBlack);
draw(chequer, Rect(0, 0, 1, 1), display->white, nil, ZP);
draw(chequer, Rect(1, 1, 2, 2), display->white, nil, ZP);
lastp = divpt(addpt(screen->r.min, screen->r.max), 2);
screenfd = open("/dev/screen", OREAD);
if(screenfd < 0){
fprint(2, "lens: can't open /dev/screen: %r\n");
exits("screen");
}
if(read(screenfd, buf, sizeof buf) != sizeof buf){
fprint(2, "lens: can't read /dev/screen: %r\n");
exits("screen");
}
chan = strtochan(buf);
d = chantodepth(chan);
if(d < 8){
fprint(2, "lens: can't handle screen format %11.11s\n", buf);
exits("screen");
}
bypp = d/8;
screenr.min.x = atoi(buf+1*12);
screenr.min.y = atoi(buf+2*12);
screenr.max.x = atoi(buf+3*12);
screenr.max.y = atoi(buf+4*12);
screenbuf = malloc(bypp*Dx(screenr)*Dy(screenr));
if(screenbuf == nil){
fprint(2, "lens: buffer malloc failed: %r\n");
exits("malloc");
}
eresized(0);

for(;;)
switch(event(&e)){
case Ekeyboard:
switch(e.kbdc){
case 'q':
case Kdel:
case Keof:
caseexit:
exits(nil);
case '=':
case '+':
casezoom:
if(mag < Maxmag){
mag++;
makegrid();
drawit();
}
break;
case 'g':
casegrid:
showgrid = !showgrid;
makegrid();
drawit();
break;
case '-':
case '_':
caseunzoom:
if(mag > 1){
mag--;
makegrid();
drawit();
}
break;
case '.':
case ' ':
caseredraw:
drawit();
break;
case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': case'0':
mag = e.kbdc-'0';
if(mag == 0)
mag = 10;
makegrid();
drawit();
break;
}
break;
case Emouse:
if(e.mouse.buttons & 1){
lastp = e.mouse.xy;
drawit();
}
if(e.mouse.buttons & 4)
switch(emenuhit(3, &e.mouse, &menu)){
case Mzoom:
goto casezoom;
case Munzoom:
goto caseunzoom;
case Mgrid:
goto casegrid;
case Mredraw:
goto caseredraw;
case Mexit:
goto caseexit;
}
break;
}
}

void
makegrid(void)
{
int m;
if (grid != nil) {
freeimage(grid);
grid = nil;
}
if (showgrid) {
m = mag;
if (m < 5)
m *= 10;
grid = allocimage(display, Rect(0, 0, m, m),
CHAN2(CGrey, 8, CAlpha, 8), 1, DTransparent);
if (grid != nil){
draw(grid, Rect(0, 0, m, 1), chequer, nil, ZP);
draw(grid, Rect(0, 1, 1, m), chequer, nil, ZP);
}
}
}

void
eresized(int new)
{
if(new && getwindow(display, Refnone) < 0){
fprint(2, "lens: can't reattach to window: %r\n");
exits("attach");
}
freeimage(tmp);
tmp = allocimage(display, Rect(0, 0, Dx(screen->r)-Edge, Dy(screen->r)-Edge+Maxmag), screen->chan, 0, DNofill);
if(tmp == nil){
fprint(2, "lens: allocimage failed: %r\n");
exits("allocimage");
}
drawit();
}

void
magnify(void)
{
int x, y, xx, yy, dd, i;
int dx, dy;
int xoff, yoff;
uchar out[8192];
uchar sp[4];

dx = (Dx(tmp->r)+mag-1)/mag;
dy = (Dy(tmp->r)+mag-1)/mag;
xoff = lastp.x-Dx(tmp->r)/(mag*2);
yoff = lastp.y-Dy(tmp->r)/(mag*2);

yy = yoff;
dd = dy;
if(yy < 0){
dd += dy;
yy = 0;
}
if(yy+dd > Dy(screenr))
dd = Dy(screenr)-yy;
seek(screenfd, 5*12+bypp*yy*Dx(screenr), 0);
if(readn(screenfd, screenbuf+bypp*yy*Dx(screenr), bypp*Dx(screenr)*dd) != bypp*Dx(screenr)*dd){
fprint(2, "lens: can't read screen: %r\n");
return;
}

for(y=0; y<dy; y++){
yy = yoff+y;
if(yy>=0 && yy<Dy(screenr))
for(x=0; x<dx; x++){
xx = xoff+x;
if(xx>=0 && xx<Dx(screenr)) /* snarf pixel at xx, yy */
for(i=0; i<bypp; i++)
sp[i] = screenbuf[bypp*(yy*Dx(screenr)+xx)+i];
else
sp[0] = sp[1] = sp[2] = sp[3] = 0;

for(xx=0; xx<mag; xx++)
if(x*mag+xx < tmp->r.max.x)
for(i=0; i<bypp; i++)
out[(x*mag+xx)*bypp+i] = sp[i];
}
else
memset(out, 0, bypp*Dx(tmp->r));
for(yy=0; yy<mag && y*mag+yy<Dy(tmp->r); yy++){
werrstr("no error");
if(loadimage(tmp, Rect(0, y*mag+yy, Dx(tmp->r), y*mag+yy+1), out, bypp*Dx(tmp->r)) != bypp*Dx(tmp->r)){
exits("load");
}
}
}
if (showgrid && mag && grid)
draw(tmp, tmp->r, grid, nil, mulpt(Pt(xoff, yoff), mag));
}