cairomm: image-surface.cc

# image-surface.cc

An example of using Cairo::ImageSurface class to render to PNG

    /* M_PI is defined in math.h in the case of Microsoft Visual C++, Solaris,
     * et. al.
     */
    #if defined(_MSC_VER)
    #define _USE_MATH_DEFINES
    #endif

    #include <string>
    #include <iostream>
    #include <cairommconfig.h>
    #include <cairomm/context.h>
    #include <cairomm/surface.h>

    #include <cmath>

    int main()
    {
        Cairo::RefPtr<Cairo::ImageSurface> surface =
            Cairo::ImageSurface::create(Cairo::FORMAT_ARGB32, 600, 400);

        Cairo::RefPtr<Cairo::Context> cr = Cairo::Context::create(surface);

        cr->save(); // save the state of the context
        cr->set_source_rgb(0.86, 0.85, 0.47);
        cr->paint();    // fill image with the color
        cr->restore();  // color is back to black now

        cr->save();
        // draw a border around the image
        cr->set_line_width(20.0);    // make the line wider
        cr->rectangle(0.0, 0.0, surface->get_width(), surface->get_height());
        cr->stroke();

        cr->set_source_rgba(0.0, 0.0, 0.0, 0.7);
        // draw a circle in the center of the image
        cr->arc(surface->get_width() / 2.0, surface->get_height() / 2.0,
                surface->get_height() / 4.0, 0.0, 2.0 * M_PI);
        cr->stroke();

        // draw a diagonal line
        cr->move_to(surface->get_width() / 4.0, surface->get_height() / 4.0);
        cr->line_to(surface->get_width() * 3.0 / 4.0, surface->get_height() * 3.0 / 4.0);
        cr->stroke();
        cr->restore();

    #ifdef CAIRO_HAS_PNG_FUNCTIONS

        std::string filename = "image.png";
        surface->write_to_png(filename);

        std::cout << "Wrote png file \"" << filename << "\"" << std::endl;

    #else

        std::cout << "You must compile cairo with PNG support for this example to work."
            << std::endl;

    #endif
    }