glfw: add monitor.getAll support

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

glfw/src/Monitor.zig

@@ -0,0 +1,42 @@
+//! Monitor type and related functions
+
+const std = @import("std");
+const mem = std.mem;
+const testing = std.testing;
+const c = @cImport(@cInclude("GLFW/glfw3.h"));
+
+pub const Error = @import("errors.zig").Error;
+const getError = @import("errors.zig").getError;
+
+const Monitor = @This();
+
+handle: *c.GLFWmonitor,
+
+/// Returns the currently connected monitors.
+///
+/// This function returns a slice of all currently connected monitors. The primary monitor is
+/// always first. If no monitors were found, this function returns an empty slice.
+///
+/// The returned slice memory is owned by the caller. The underlying handles are owned by GLFW, and
+/// are valid until the monitor configuration changes or the `glfw.terminate` is called.
+///
+/// @thread_safety This function must only be called from the main thread.
+///
+/// see also: monitor_monitors, monitor_event, glfw.monitor.getPrimary
+pub fn getAll(allocator: *mem.Allocator) ![]Monitor {
+    var count: c_int = 0;
+    const monitors = c.glfwGetMonitors(&count);
+
+    const slice = allocator.alloc(Monitor, count);
+    var i = 0;
+    while (i < count) : (i += 1) {
+        slice[i] = Monitor{ .handle = monitors[i] };
+    }
+    return slice;
+}
+
+test "getAll" {
+    const allocator = testing.allocator;
+    const monitors = try getAll(allocator);
+    defer allocator.free(monitors);
+}

glfw/src/main.zig

@@ -14,6 +14,7 @@ pub const hat = @import("hat.zig");
 pub const joystick = @import("joystick.zig");
 pub const key = @import("key.zig");
 pub const mod = @import("mod.zig");
+pub const Monitor = @import("Monitor.zig");
 pub const mouse_button = @import("mouse_button.zig");
 pub const version = @import("version.zig");