.TH DRAW-EXAMPLE 2.SH NAMEdraw: example \-simple program illustrating image primitives.SH DESCRIPTIONThis manual page presents a self-contained simple program that illustrates mostof the feature of the basic draw library.It must be run at the top-level Inferno shell prompt, not within a window system,as it establishes its own connection to the display and writes directlyon the display, not in a private window..PPThe program exercises the drawing primitives, taking particular careto maintain a consistent coordinate system for the combinations ofimages on the display.  Comments in the code introduce each step..PP.EXimplement Test; include "sys.m"; include "draw.m"; Test: module{	init:	fn(ctxt: ref Draw->Context, argv: list of string);}; init(nil: ref Draw->Context, nil: list of string){	sys := load Sys Sys->PATH;	draw := load Draw Draw->PATH;	Display, Font, Rect, Point, Image, Screen: import draw; 	#	# Set up connection to display and initialize colours.	#	display := draw->Display.allocate(nil);	disp := display.image;	red := display.color(Draw->Red);	blue := display.color(Draw->Blue);	white := display.color(Draw->White);	yellow := display.color(Draw->Yellow); 	#	# Paint the screen red.	#	disp.draw(disp.r, red, nil, disp.r.min);	sys->sleep(5000); 	#	# Texture a region with rectangular tiles.	#	texture := display.newimage(((0,0),(2,3)),		disp.chans, 1, Draw->Black);	texture.clipr = ((-10000,-10000),(10000,10000));	# put something in the texture	texture.draw(((0,0),(1,3)), white, nil, (0,0));	texture.draw(((0,0),(2, 1)), white, nil, (0,0));	# use texture as both source and mask to let	# destination colour show through	disp.draw(((100,100),(200,300)), texture,		texture, (0,0));	sys->sleep(5000); 	#	# White-out a quarter of the pixels in a region,	# to make the region appear shaded.	#	stipple := display.newimage(((0,0),(2,2)),				disp.chans, 1, Draw->Transparent);	stipple.draw(((0,0),(1,1)), display.opaque,				nil, (0,0));	disp.draw(((100,100),(300,250)), white,				stipple, (0,0));	sys->sleep(5000); 	#	# Draw textured characters.	#	font := Font.open(display, "*default*");	disp.text((100,310), texture, (0,0), font,			"Hello world");	sys->sleep(5000); 	#	# Draw picture in elliptical frame.	#	delight := display.open("/icons/delight.bit");	piccenter := delight.r.min.add(delight.r.max).div(2);	disp.fillellipse((250,250), 150, 50,		delight, piccenter);	disp.ellipse((250,250), 150, 50, 3, yellow, (0,0));	sys->sleep(5000); 	#	# Draw a parabolic brush stroke using an elliptical brush	# to reveal more of the picture, consistent with what's	# already visible.	#	dx : con 15;	dy : con 3;	brush := display.newimage(((0,0),(2*dx+1,2*dy+1)), disp.chans,                               0, Draw->Black);	brush.fillellipse((dx,dy), dx, dy, display.white,				(0,0));	for(x:=delight.r.min.x; x<delight.r.max.x; x++){		y := (x-piccenter.x)*(x-piccenter.x)/80;		y += 2*dy+1;	# so whole brush is visible at top		xx := x+(250-piccenter.x)-dx;		yy := y+(250-piccenter.y)-dy;		disp.gendraw(((xx,yy),(xx+2*dx+1,yy+2*dy+1)),                       delight, (x-dx, y-dy), brush,			(0,0));	}}.EE