[cairo] Uninitialized Values

[cecashon at aol.com]

With valgrind I get a lot of uninitialised values with the following program. Everything draws fine. If the radial pattern code gets commented out then these errors don't occur. A little stuck on this one.

Eric



==3380== Use of uninitialised value of size 4
==3380==    at 0x473B1A5: crc32 (in /lib/i386-linux-gnu/libz.so.1.2.8)
==3380==    by 0x456E374: ??? (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x4576E3F: png_write_chunk_data (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x4576FE5: png_write_chunk (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x457777D: ??? (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x45794A4: ??? (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x4579B3F: ??? (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x4579E60: ??? (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x457DD3F: png_write_row (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x457DF7E: png_write_image (in /lib/i386-linux-gnu/libpng12.so.0.54.0)
==3380==    by 0x4110033: ??? (in /usr/lib/i386-linux-gnu/libcairo.so.2.11400.6)
==3380==    by 0x4110A6A: cairo_surface_write_to_png (in /usr/lib/i386-linux-gnu/libcairo.so.2.11400.6)
==3380==  Uninitialised value was created by a stack allocation
==3380==    at 0x440AB5E: ??? (in /usr/lib/i386-linux-gnu/libpixman-1.so.0.33.6)

/* 
    gcc -Wall -Wextra -g -O0 cairo_test1.c -o cairo_test1 `pkg-config --cflags --libs cairo` -lm

    valgrind --leak-check=full --show-leak-kinds=all --track-origins=yes ./cairo_test1

    Tested on 32bit Ubuntu16.04
*/

#include<cairo.h>
#include<stdio.h>
#include<math.h>

int main()
  {
    int i=0;
    double width=400.0;
    double height=400.0;
    double data[12][2];
    cairo_surface_t *surface=cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
    cairo_t *cr=cairo_create(surface);

    for(i=0;i<12;i++)
      {
        data[i][0]=(width/4)*cos(30.0*(double)(i)*M_PI/180.0);
        data[i][1]=(height/4)*sin(30.0*(double)(i)*M_PI/180.0);
      }
   
    cairo_set_source_rgba(cr, 0.0, 1.0, 0.0, 1.0);
    cairo_paint(cr);

    //cairo_set_source_rgba(cr, 0.0, 0.0, 1.0, 1.0);
    cairo_translate(cr, width/2.0, height/2.0);
    cairo_pattern_t *radial1=cairo_pattern_create_radial(0.0, 0.0, 0.0, 0.0, 0.0, width/4.0);  
    cairo_pattern_add_color_stop_rgba(radial1, 0.0, 1.0, 0.0, 0.0, 1.0);
    cairo_pattern_add_color_stop_rgba(radial1, 1.0, 0.0, 0.0, 1.0, 1.0);
    cairo_set_source(cr, radial1);

    cairo_move_to(cr, data[0][0], data[0][1]);
    for(i=1;i<12;i++)
      {
        cairo_line_to(cr, data[i][0], data[i][1]);
        cairo_stroke_preserve(cr);
      }
    cairo_close_path(cr);
    cairo_fill(cr);  

    cairo_surface_write_to_png(surface, "drawing1.png");
    printf("Status %i\n", cairo_status(cr));
    
    cairo_pattern_destroy(radial1);
    cairo_destroy(cr);
    cairo_surface_destroy(surface);
    cairo_debug_reset_static_data();
 
    return 0;
  }
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