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#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <cairo.h>
#include <stdio.h>
#include "chart.h"
int chart_init(struct chart *chart, const char *name, int num_samples)
{
memset(chart, 0, sizeof(*chart));
chart->name = name;
chart->samples = malloc(sizeof(*chart->samples)*num_samples);
if (chart->samples == NULL)
return ENOMEM;
chart->num_samples = num_samples;
chart->range_automatic = 1;
return 0;
}
void chart_set_rgba(struct chart *chart, float red, float green, float blue, float alpha)
{
chart->rgb[0] = red;
chart->rgb[1] = green;
chart->rgb[2] = blue;
chart->rgb[3] = alpha;
}
void chart_set_position(struct chart *chart, int x, int y)
{
chart->x = x;
chart->y = y;
}
void chart_set_size(struct chart *chart, int w, int h)
{
chart->w = w;
chart->h = h;
}
void chart_set_range(struct chart *chart, double min, double max)
{
chart->range[0] = min;
chart->range[1] = max;
chart->range_automatic = 0;
}
void chart_add_sample(struct chart *chart, double value)
{
int pos;
pos = chart->current_sample % chart->num_samples;
chart->samples[pos] = value;
chart->current_sample++;
}
static void chart_update_range(struct chart *chart)
{
int n, max = chart->current_sample;
if (max > chart->num_samples)
max = chart->num_samples;
chart->range[0] = chart->range[1] = chart->samples[0];
for (n = 1; n < max; n++) {
if (chart->samples[n] < chart->range[0])
chart->range[0] = chart->samples[n];
else if (chart->samples[n] > chart->range[1])
chart->range[1] = chart->samples[n];
}
}
static double value_at(struct chart *chart, int n)
{
if (n <= chart->current_sample - chart->num_samples)
n = chart->current_sample;
else if (n >= chart->current_sample)
n = chart->current_sample - 1;
return chart->samples[n % chart->num_samples];
}
static double gradient_at(struct chart *chart, int n)
{
double y0, y1;
y0 = value_at(chart, n-1);
y1 = value_at(chart, n+1);
return (y1 - y0) / 2.;
}
void chart_draw(struct chart *chart, cairo_t *cr)
{
int i, n, max, x;
if (chart->current_sample == 0)
return;
if (chart->range_automatic)
chart_update_range(chart);
cairo_save(cr);
cairo_translate(cr, chart->x, chart->y + chart->h);
cairo_scale(cr,
chart->w / (double)chart->num_samples,
-chart->h / (chart->range[1] - chart->range[0]));
x = 0;
max = chart->current_sample;
if (max >= chart->num_samples) {
max = chart->num_samples;
i = chart->current_sample - max;
} else {
i = 0;
x = chart->num_samples - max;
}
cairo_translate(cr, x, -chart->range[0]);
cairo_new_path(cr);
for (n = 0; n < max; n++) {
cairo_curve_to(cr,
n-2/3., value_at(chart, i + n -1) + gradient_at(chart, i + n - 1)/3.,
n-1/3., value_at(chart, i + n) - gradient_at(chart, i + n)/3.,
n, value_at(chart, i + n));
}
cairo_identity_matrix(cr);
cairo_set_line_width(cr, 1);
cairo_set_source_rgba(cr, chart->rgb[0], chart->rgb[1], chart->rgb[2], chart->rgb[3]);
cairo_stroke(cr);
cairo_restore(cr);
}
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