GLEQ — GLFW Event Queue

GLEQ is a simple, header-only event queue library for GLFW 3. It adds GLFW events for tracked windows to a single global queue. Nothing more.

GLEQ is inspired by SDL and GLWT, and is written as an example for people requesting that GLFW provide an event queue API, to show how easy it is to implement on top of GLFW callbacks.

GLEQ is written in C89 and depends only on GLFW 3.1 or later, as no new window events were added in GLFW 3.2.

GLEQ is a work in progress. It is undocumented and may change name, but it works as intended and covers all window related events up to and including GLFW 3.2. Just drop it into your project and include it.

GLEQ is licensed under the zlib/libpng license.

Using GLEQ

To use GLEQ, include gleq.h after the GLFW header. To add the implementation of GLEQ, define GLEQ_IMPLEMENTATION before including the GLEQ header in exactly one source file.

#include <GLFW/glfw3.h>

#define GLEQ_IMPLEMENTATION
#include "gleq.h"

If you will only be using GLEQ in a single source file, you can make all its functions static by defining GLEQ_STATIC as well.

#include <GLFW/glfw3.h>

#define GLEQ_IMPLEMENTATION
#define GLEQ_STATIC
#include "gleq.h"

Once a GLFW window is created, you can track it with gleqTrackWindow. This replaces all callback on that window. You should not set any callbacks on a tracked window.

gleqTrackWindow(window);

Event polling and waiting is done as usual with glfwPollEvents and glfwWaitEvents. Available events for tracked windows are added to the queue when you call one of these.

Event retrieval is done with gleqNextEvent.

GLEQevent event;

while (gleqNextEvent(&event))
{
    switch (event.type)
    {
        case GLEQ_WINDOW_RESIZED:
            printf("Window resized to %ix%i\n",
                   event.size.width, event.size.height);
            break;
    }

    gleqFreeEvent(&event);
}

The call to gleqFreeEvent frees any memory allocated for the event and clears the event struct. Currently only the file drop event allocates memory, but it's recommended to call it for every event once it has been processed.

FAQ

Does GLEQ use the GLFW window user pointer?

No, only window related callbacks.

Does GLEQ allocate memory?

Only to save a deep copy of the path list provided to the file drop callback. The event queue itself is a global static array.

Aren't static arrays bad?

It depends. Also, the size of the queue can be controlled with GLEQ_CAPACITY.

Isn't global data bad?

It depends. The native event queue wrapped by GLFW is global, too.

Why doesn't GLEQ provide one queue per window?

GLEQ is intended to be a simple example event queue. Having a queue per window would make it more complicated than it needs to be.

Why isn't GLEQ thread safe?

GLEQ is intended to be a simple example event queue. Making it thread safe would make it more complicated than it needs to be.