[cairo] Shouldn't Cairo use/offer degrees rather than radians?
cecashon at aol.com
cecashon at aol.com
Fri Jul 7 04:20:43 UTC 2017
If I take a look at the pixels, I can see the arc not making a half circle in this case. When I run the following program I get this output. This is with cairo 1.14.6. If I try the same program with Valgrind the half circle lines up?
Eric
...
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 255 255 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
255 255 255 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
255 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
...
With Valgrind
...
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 255 255 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 255 255 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 255 255 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
...
#include <cairo.h>
#include <stdio.h>
#include <math.h>
int main()
{
//cairo_surface_t *surface = cairo_image_surface_create (CAIRO_FORMAT_RGB16_565, 30, 20);
cairo_surface_t *surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 30, 20);
cairo_t *cr = cairo_create (surface);
cairo_set_line_width (cr, 2);
cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
cairo_paint(cr);
cairo_set_source_rgb (cr, 0.0, 1.0, 0.0);
cairo_arc (cr, 15, 0.501954078674316, 5, 0, M_PI);
cairo_stroke (cr);
cairo_destroy (cr);
int i=0;
int j=0;
cairo_surface_flush(surface);
int width = cairo_image_surface_get_width(surface);
int height = cairo_image_surface_get_height(surface);
int stride = cairo_format_stride_for_width (CAIRO_FORMAT_ARGB32, 30);
int channels = 4;
unsigned char *s=cairo_image_surface_get_data(surface);
unsigned char *pixels=s;
for(i=0;i<width;i++)
{
for(j=0;j<height;j++)
{
printf("%3i ", pixels[j*stride+i*channels+1]);
}
printf("\n");
}
cairo_surface_destroy (surface);
return 0;
}
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