fb_configs.hpp

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#ifndef EAGINE_INTEROP_GLX_FB_CONFIGS_HPP
#define EAGINE_INTEROP_GLX_FB_CONFIGS_HPP
 
#include "../x11/display.hpp"
#include "../x11/visual_info.hpp"
#include "fb_config.hpp"
#include <eagine/assert.hpp>
 
#include <GL/glx.h>
#include <stdexcept>
#include <utility>
 
namespace eagine::glx {
 
class fb_configs {
private:
    int _count{0};
    GLXFBConfig* _handle{nullptr};
 
public:
    fb_configs(const x11::display& dpy, const int* visual_attribs)
      : _handle(::glXChooseFBConfig(
          dpy,
          DefaultScreen(dpy.get()),
          visual_attribs,
          &_count)) {
        if(!_handle || (_count <= 0)) {
            throw std::runtime_error(
              "Failed to get matching framebuffer configs");
        }
    }
 
    fb_configs(fb_configs&& temp) noexcept
      : _count(std::exchange(temp._count, 0))
      , _handle(std::exchange(temp._handle, nullptr)) {}
 
    fb_configs(const fb_configs&) = delete;
    auto operator=(fb_configs&&) = delete;
    auto operator=(const fb_configs&) = delete;
 
    ~fb_configs() {
        if(_handle) {
            ::XFree(_handle);
        }
    }
 
    auto find_best(const x11::display& dpy) const -> fb_config {
        int best = -1, best_num = -1;
        EAGINE_ASSERT(_count > 0);
        for(int i = 0; i != _count; ++i) {
            int sample_buf, samples;
 
            ::glXGetFBConfigAttrib(
              dpy, _handle[i], GLX_SAMPLE_BUFFERS, &sample_buf);
            ::glXGetFBConfigAttrib(dpy, _handle[i], GLX_SAMPLES, &samples);
            if((best < 0) || (sample_buf && (samples > best_num))) {
                best = i;
                best_num = samples;
            }
        }
        EAGINE_ASSERT(best >= 0);
        EAGINE_ASSERT(best < _count);
        return fb_config(_handle[best]);
    }
};
 
} // namespace eagine::glx
 
#endif