Added support for custom system cursors.

This adds 3 functions to the GLFW API: glfwCreateCursor,
glfwDestroyCursor and glfwSetCursor.

tests/cursoranim.c

@@ -0,0 +1,133 @@
+//========================================================================
+// Cursor animation
+// 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.
+//
+//========================================================================
+//
+// Cursor animation test.
+//
+//========================================================================
+
+#include <GLFW/glfw3.h>
+
+#include <stdlib.h>
+#include <math.h>
+
+#ifdef min
+ #undef min
+#endif
+#ifdef max
+ #undef max
+#endif
+
+#define SIZE 64  // cursor size (width & height)
+#define N    60  // number of frames
+
+unsigned char buffer[4 * SIZE * SIZE];
+
+static float max(float a, float b) { return a > b ? a : b; }
+static float min(float a, float b) { return a < b ? a : b; }
+
+static float star(int x, int y, float t)
+{
+    float c = SIZE / 2.0f;
+
+    float i = (0.25f * (float)sin(2.0f * 3.1415926f * t) + 0.75f);
+    float k = SIZE * 0.046875f * i;
+
+    float dist = (float)sqrt((x - c) * (x - c) + (y - c) * (y - c));
+
+    float salpha = 1.0f - dist / c;
+    float xalpha = (float)x == c ? c : k / (float)fabs(x - c);
+    float yalpha = (float)y == c ? c : k / (float)fabs(y - c);
+
+    return max(0.0f, min(1.0f, i * salpha * 0.2f + salpha * xalpha * yalpha));
+}
+
+static GLFWcursor* load_frame(float t)
+{
+    int i = 0, x, y;
+
+    for (y = 0; y < SIZE; y++)
+    {
+        for (x = 0; x < SIZE; x++)
+        {
+            buffer[i++] = 255;
+            buffer[i++] = 255;
+            buffer[i++] = 255;
+            buffer[i++] = (unsigned char)(255 * star(x, y, t));
+        }
+    }
+
+    return glfwCreateCursor(SIZE, SIZE, SIZE / 2, SIZE / 2, 0, buffer);
+}
+
+int main(void)
+{
+    int i;
+    double t0, t1, frameTime = 0.0;
+
+    GLFWwindow* window;
+    GLFWcursor* frames[N];
+
+    if (!glfwInit())
+        exit(EXIT_FAILURE);
+
+    window = glfwCreateWindow(640, 480, "Cursor animation", NULL, NULL);
+
+    if (!window)
+    {
+        glfwTerminate();
+        exit(EXIT_FAILURE);
+    }
+
+    glfwMakeContextCurrent(window);
+    glfwSwapInterval(1);
+
+    for (i = 0; i < N; i++)
+        frames[i] = load_frame(i / (float)N);
+
+    i = 0;
+
+    t0 = glfwGetTime();
+
+    while (!glfwWindowShouldClose(window))
+    {
+        glClear(GL_COLOR_BUFFER_BIT);
+        glfwSetCursor(window, frames[i]);
+        glfwSwapBuffers(window);
+        glfwPollEvents();
+
+        t1 = glfwGetTime();
+        frameTime += t1 - t0;
+        t0 = t1;
+
+        while (frameTime > 1.0 / (double)N)
+        {
+            i = (i + 1) % N;
+            frameTime -= 1.0 / (double)N;
+        }
+    }
+
+    glfwTerminate();
+    exit(EXIT_SUCCESS);
+}