[cairo-commit] cairo-5c/examples pie.5c,NONE,1.1

[Keith Packard]

Committed by: keithp

Update of /cvs/cairo/cairo-5c/examples
In directory gabe:/tmp/cvs-serv12008/examples

Added Files:
	pie.5c 
Log Message:
2004-12-10  Keith Packard  <keithp at keithp.com>

	* examples/pie.5c:
	Add text example
	* init.c: (nickle_init):
	Set return type of text_extents function correctly


--- NEW FILE: pie.5c ---
#!/usr/bin/env nickle

if (!Command::valid_name ((string[]) { "Cairo" }))
    Foreign::load ("libcairo-5c.so");
    
import Cairo;

typedef foreign cairo_t;

real[3] rgb_to_hsv(real[3] rgb)
{
    real min, max, delta;
    int i, w;
    real[3] hsv;

    w = 0;
    min = max = rgb[0];
    for(i=0; i<3; i++) {
	if (rgb[i]<min) min = rgb[i];
	if (rgb[i]>max) { max = rgb[i]; w = i; }
    }

    /* calculate V */
    hsv[2] = max;

    /* calculate S */
    if (max>0.00000001)
	hsv[1] = ((max-min)/max);
    else
	hsv[1] = 0.0;

    /* calculate H */
    if (hsv[1]<=0.000001) {

    } else {
	delta = max-min;
	switch(w) {
	case 0: hsv[0] = 60.0*(0.0 + (rgb[1]-rgb[2])/delta); break;
	case 1: hsv[0] = 60.0*(2.0 + (rgb[2]-rgb[0])/delta); break;
	case 2: hsv[0] = 60.0*(4.0 + (rgb[0]-rgb[1])/delta); break;
	}
	while (hsv[0] < 0.0) hsv[0] += 360.0;
    }
    return hsv;
}

/* convert hsv to rgb */

real[3] hsv_to_rgb(real[3] hsv) 
{
    real h,s,v,f,p,q,t;
    int i;
    real[3] rgb;

    h = hsv[0];
    s = hsv[1];
    v = hsv[2];

    if(s <= 0.0000001) {
	for(i=0; i<3; i++)
	    rgb[i] = v;
    } else {
	while(h<0.0) h+=360.0;
	while(h>=360.0) h-=360.0;

	h /= 60.0;
	i = floor (h);
	f = h - i;
	p = v*(1.0-s);
	q = v*(1.0-(s*f));
	t = v*(1.0-(s*(1.0-f)));

	switch(i) {
	case 0: rgb[0] = v; rgb[1] = t; rgb[2] = p; break;
	case 1: rgb[0] = q; rgb[1] = v; rgb[2] = p; break;
	case 2: rgb[0] = p; rgb[1] = v; rgb[2] = t; break;
	case 3: rgb[0] = p; rgb[1] = q; rgb[2] = v; break;
	case 4: rgb[0] = t; rgb[1] = p; rgb[2] = v; break;
	case 5: rgb[0] = v; rgb[1] = p; rgb[2] = q; break;
	}
    }
    return rgb;
}

void set_hsv_color (foreign cr, real h, real s, real v)
{
    real[3] rgb = hsv_to_rgb ((real[3]) { h, s, v });
    Cairo::set_rgb_color (cr, rgb[0], rgb[1], rgb[2]);
}

real π = pi;
real text_width (cairo_t cr, string text) = text_extents (cr, text).width;
real text_height(cairo_t cr, string text) = text_extents (cr, text).height;

void circle_text (cairo_t cr, string text)
{
    real    circumference = 0;
    
    for (int i = 0; i < String::length(text); i++)
	circumference += text_width (cr, String::substr(text,i,1));

    real radius = circumference / (2 * π);

    real height = text_height (cr, text) * 2;

    translate (cr, radius + height, radius + height);

    real θ = -π ÷ 2;
    for (int i = 0; i < String::length(text); i++)
    {
	string	c = String::substr (text, i, 1);
	real	width = text_width (cr, c);
	
	save (cr);
	rotate (cr, θ + π ÷ 2);
	
	translate   (cr, -width ÷ 2, -radius);
	
	move_to (cr, 0, 0);
	
	show_text (cr, c);
	restore (cr);
	θ += asin ((width ÷ 2) / radius) * 2;
    }
}

void spiral_text (cairo_t cr, string text)
{
    real    circumference = 0;
    
    translate (cr, width(cr) / 2, height(cr) / 2);

    real height = text_height (cr, text) * 3;

    real θ = -π ÷ 2;
    for (int i = 0; i < String::length(text); i++)
    {
	string	c = String::substr (text, i, 1);
	real	width = text_width (cr, c);
	
	real radius = ((θ + π) * height / (2 × π));

	save (cr);
	rotate (cr, θ + π ÷ 2);
	set_hsv_color (cr, θ * 180 / π, 1, 0.7);
	
	translate   (cr, -width ÷ 2, -radius);
	
	move_to (cr, 0, 0);
	
	show_text (cr, c);
	restore (cr);
	θ += asin ((width ÷ 2) / radius) * 2;
    }
}

void pie (int bits)
{
    cairo_t cr = new (700, 700);
    sleep (100);
    select_font (cr, "sans-serif", 0, 0);
    scale_font (cr, 10);
    spiral_text (cr, sprintf ("%.-g", pi_value (bits)));
}