glfw/tests/accuracy.c

//========================================================================
// Mouse cursor accuracy test
// Copyright (c) Camilla Berglund <elmindreda@elmindreda.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================
//
// This test came about as the result of bug #1867804
//
// No sign of said bug has so far been detected
//
//========================================================================

#define GLFW_INCLUDE_GLU
#include <GL/glfw3.h>

#include <stdio.h>
#include <stdlib.h>

static int cursor_x = 0, cursor_y = 0;
static int window_width = 640, window_height = 480;
static int swap_interval = 1;

static void set_swap_interval(GLFWwindow window, int interval)
{
    char title[256];

    swap_interval = interval;
    glfwSwapInterval(swap_interval);

    snprintf(title, sizeof(title),
             "Cursor Inaccuracy Detector (interval %i)",
             swap_interval);

    glfwSetWindowTitle(window, title);
}

static void window_size_callback(GLFWwindow window, int width, int height)
{
    window_width = width;
    window_height = height;

    glViewport(0, 0, window_width, window_height);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.f, window_width, 0.f, window_height);
}

static void cursor_position_callback(GLFWwindow window, int x, int y)
{
    cursor_x = x;
    cursor_y = y;
}

static void key_callback(GLFWwindow window, int key, int action)
{
    if (key == GLFW_KEY_SPACE && action == GLFW_PRESS)
        set_swap_interval(window, 1 - swap_interval);
}

int main(void)
{
    GLFWwindow window;
    int width, height;

    if (!glfwInit())
    {
        fprintf(stderr, "Failed to initialize GLFW: %s\n", glfwErrorString(glfwGetError()));
        exit(EXIT_FAILURE);
    }

    glfwSetCursorPosCallback(cursor_position_callback);
    glfwSetWindowSizeCallback(window_size_callback);
    glfwSetKeyCallback(key_callback);

    window = glfwCreateWindow(window_width, window_height, GLFW_WINDOWED, "", NULL);
    if (!window)
    {
        glfwTerminate();

        fprintf(stderr, "Failed to open GLFW window: %s\n", glfwErrorString(glfwGetError()));
        exit(EXIT_FAILURE);
    }

    glfwGetWindowSize(window, &width, &height);
    window_size_callback(window, width, height);

    set_swap_interval(window, swap_interval);

    while (glfwGetCurrentContext())
    {
        glClear(GL_COLOR_BUFFER_BIT);

        glBegin(GL_LINES);
        glVertex2f(0.f, (GLfloat) window_height - cursor_y);
        glVertex2f((GLfloat) window_width, (GLfloat) window_height - cursor_y);
        glVertex2f((GLfloat) cursor_x, 0.f);
        glVertex2f((GLfloat) cursor_x, (GLfloat) window_height);
        glEnd();

        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwTerminate();
    exit(EXIT_SUCCESS);
}