text: //========================================================================
  // Window icon test program
  // 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 program is used to test the icon feature.
  //
  //========================================================================
  
  #include <glad/glad.h>
  #include <GLFW/glfw3.h>
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  // a simple glfw logo
  const char* const logo[] =
  {
      "................",
      "................",
      "...0000..0......",
      "...0.....0......",
      "...0.00..0......",
      "...0..0..0......",
      "...0000..0000...",
      "................",
      "................",
      "...000..0...0...",
      "...0....0...0...",
      "...000..0.0.0...",
      "...0....0.0.0...",
      "...0....00000...",
      "................",
      "................"
  };
  
  const unsigned char icon_colors[5][4] =
  {
      {   0,   0,   0, 255 }, // black
      { 255,   0,   0, 255 }, // red
      {   0, 255,   0, 255 }, // green
      {   0,   0, 255, 255 }, // blue
      { 255, 255, 255, 255 }  // white
  };
  
  static int cur_icon_color = 0;
  
  static void set_icon(GLFWwindow* window, int icon_color)
  {
      int x, y;
      unsigned char pixels[16 * 16 * 4];
      unsigned char* target = pixels;
      GLFWimage img = { 16, 16, pixels };
  
      for (y = 0;  y < img.width;  y++)
      {
          for (x = 0;  x < img.height;  x++)
          {
              if (logo[y][x] == '0')
                  memcpy(target, icon_colors[icon_color], 4);
              else
                  memset(target, 0, 4);
  
              target += 4;
          }
      }
  
      glfwSetWindowIcon(window, 1, &img);
  }
  
  static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
  {
      if (action != GLFW_PRESS)
          return;
  
      switch (key)
      {
          case GLFW_KEY_ESCAPE:
              glfwSetWindowShouldClose(window, GLFW_TRUE);
              break;
          case GLFW_KEY_SPACE:
              cur_icon_color = (cur_icon_color + 1) % 5;
              set_icon(window, cur_icon_color);
              break;
          case GLFW_KEY_X:
              glfwSetWindowIcon(window, 0, NULL);
              break;
      }
  }
  
  int main(int argc, char** argv)
  {
      GLFWwindow* window;
  
      if (!glfwInit())
      {
          fprintf(stderr, "Failed to initialize GLFW\n");
          exit(EXIT_FAILURE);
      }
  
      window = glfwCreateWindow(200, 200, "Window Icon", NULL, NULL);
      if (!window)
      {
          glfwTerminate();
  
          fprintf(stderr, "Failed to open GLFW window\n");
          exit(EXIT_FAILURE);
      }
  
      glfwMakeContextCurrent(window);
      gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
  
      glfwSetKeyCallback(window, key_callback);
      set_icon(window, cur_icon_color);
  
      while (!glfwWindowShouldClose(window))
      {
          glClear(GL_COLOR_BUFFER_BIT);
          glfwSwapBuffers(window);
          glfwWaitEvents();
      }
  
      glfwDestroyWindow(window);
      glfwTerminate();
      exit(EXIT_SUCCESS);
  }
  
  