cgraph

A single header C99 library to create graphs and plots.

⚠️Currently in extremely early alpha

Functional Goals

• Allow users to create a variety of graphs
• Export said graphs to a variety of image formats
• Not rely on any third-party dependencies (ie handle all the rendering internally)
• Allow users to customize the look/style of their graphs

Current Functionality

• Bar Graphs
• Horizontal Bar Graphs
• Pie Charts

Usage

Simply define CGRAPH_IMPLEMENTATION and then include the header file:

#define CGRAPH_IMPLEMENTATION
#include "cgraph.h"

As of right now (12-29-2025) cgraph only supports creating bar graphs and pie charts. Here is an example of how you would create a bar graph:

#define CGRAPH_IMPLEMENTATION
#include "cgraph.h"

int main() {
  cg_bar_graph bg = cg_new_bar_graph("Foobar"); // create the bar graph
  
// add the individual bars, their labels, their values, and their colours
  cg_bar_graph_add_bar(&bg, "Foo", 40, (cg_colour){255, 0, 0});
  cg_bar_graph_add_bar(&bg, "Bar", 82, (cg_colour){0, 0, 255});
  cg_bar_graph_add_bar(&bg, "Baz", 67, (cg_colour){0, 255, 0});

  cg_image img = cg_bar_graph_render(&bg); // render the graph into an image 
  cg_bar_graph_free(bg);

  cg_image_export(img, "graph.ppm", PPM); // export the graph
  cg_image_free(img);
}

The output will then look something like this:

Here is how you would create a pie graph:

#define CGRAPH_IMPLEMENTATION
#include "cgraph.h"

int main() {
  cg_pie_graph pg = cg_new_pie_graph("Foobar");
  cg_pie_graph_add_slice(&pg, "Foo", 20, (cg_colour){255, 0, 0});
  cg_pie_graph_add_slice(&pg, "Bar", 40, (cg_colour){0, 255, 0});
  cg_pie_graph_add_slice(&pg, "Baz", 40, (cg_colour){0, 0, 255});

  cg_image img = cg_pie_graph_render(&pg);
  cg_image_export(img, "circle.ppm", PPM);
  cg_image_free(img);

}

The output will look something like this:

License

cgraph is licensed under the MIT license