Use the Cairo graphics library in C to draw a pie chart

Many people still stick to the graphics of Turbo C by directly drawing in C language. in the age of H, there may also be reasons for the aging of education. After all, the classic has become a thing of the past. Instead of trying every means to find a compatible graphics library, it is better to embrace the bright future. Cario (http://cairographics.org/) is a very good 2D graphics library, the famous GTK + 3.0 fully uses Cario as the drawing engine, it shows its strong and attractive.

Cario supports multiple output devices, including X Window, quartz, Win32, image. buffers, postscript, PDF, and SVG files. It is open source and cross-platform. Some people may think that such a powerful thing will be very tricky to use. In fact, the API functions it provides are unexpectedly simple and easy to use, the author demonstrates an example of drawing a plot for your reference.

# Include <Cairo. h> # define size (640)/* resize image size */# define Cx (size/2)/* horizontal coordinate of the Center of Taiji circle */# define cy (size/2) /* Y coordinate of the center of the Taiji circle */# define R (size/2) /* * // * converts the angle to the corresponding radian */# define angle (ANG * 3.1415926/180.0) int main (INT argc, char * argv []) {/* Create a 32-bit rgba color Cairo drawing environment and render it directly in memory */cairo_surface_t * surface = cairo_image_surface_create (cairo_format_argb32, size + 1, size + 1); cairo_t * Cr = cairo_create (surface);/* draw a taiji border */cairo_set_line_width (Cr, 2.0); cairo_set_source_rgba (Cr, 0, 0, 0, 0, 1); cairo_arc (Cr, CX, Cy, R, angle (0), angle (360); cairo_stroke (CR);/* plot yin and yang circles */cairo_set_source_rgba (Cr, 0, 0, 0, 1); cairo_arc (Cr, CX, Cy, R, angle (90), angle (270); cairo_fill (CR); cairo_set_source_rgba (Cr, 1, 1, 1, 1); cairo_arc (Cr, CX, Cy, R, angle (-90), angle (90); cairo_fill (CR ); /* draw Yin/yang line */cairo_set_source_rgba (Cr, 0, 0, 0, 1); cairo_arc (Cr, CX, cy-r/2, R/2, angle (-90), angle (90); cairo_fill (CR); cairo_set_source_rgba (Cr, 1, 1, 1); cairo_arc (Cr, CX, cy + R/2, R/2, angle (90), angle (270); cairo_fill (CR);/* draw Taiji eyes */cairo_set_source_rgba (Cr, 1, 1, 1, 1); cairo_arc (Cr, CX, cy-r/2, R/10, angle (0), angle (360); cairo_fill (CR ); cairo_set_source_rgba (Cr, 0, 0, 0, 1); cairo_arc (Cr, CX, Cy + R/2, R/10, angle (0), angle (360 )); cairo_fill (CR);/* store the rendering Effect of memory to the image */cairo_surface_write_to_png (surface, "taichi.png "); /* destroy and exit the Cairo drawing environment */cairo_destroy (CR); cairo_surface_destroy (surface); Return 0 ;}

The code is very simple. I hope more people will like the Cario graphics library. For GCC compilation, refer to the following command.

gcc -o taichi $(pkg-config --cflags --libs cairo) taichi.c

This is the effect after running. You can try it.