Added GLFW_FLOATING.

Fixes #23.

README.md

@@ -63,6 +63,7 @@ GLFW bundles a number of dependencies in the `deps/` directory.
  - Added `GLFW_DONT_CARE` for indicating that any value is acceptable
  - Added `GLFW_DOUBLEBUFFER` for controlling whether to use double buffering
  - Added `GLFW_INCLUDE_ES31` for including the OpenGL ES 3.1 header
+ - Added `GLFW_FLOATING` for creating always-on-top windowed mode windows
  - Added *partial and experimental* support for Wayland
  - Bugfix: The debug context attribute was set from `GL_ARB_debug_output` even
            when a debug context had not been requested

docs/news.dox

@@ -41,6 +41,12 @@ building multi-monitor installations, where you need windows to stay in full
 screen despite losing focus.
 
 
+@subsection news_31_floating Floating windows
+
+GLFW not supports floating windows, also called topmost or always on top, for
+easier debugging, with the `GLFW_FLOATING` window hint.
+
+
 @section news_30 New features in version 3.0
 
 @subsection news_30_cmake CMake build system

docs/window.dox

@@ -122,6 +122,11 @@ The `GLFW_AUTO_ICONIFY` hint specifies whether the (full screen) window
 will automatically iconify and restore the previous video mode on focus loss.
 This hint is ignored for windowed mode windows.
 
+The `GLFW_FLOATING` hint specifies whether the window will be floating above
+other regular windows, also called topmost or always-on-top.  This is intended
+primarily for debugging purposes and cannot be used to implement proper full
+screen windows.  This hint is ignored for full screen windows.
+
 
 @subsection window_hints_fb Framebuffer related hints
 
@@ -211,6 +216,7 @@ a robustness strategy.
 | `GLFW_VISIBLE`               | `GL_TRUE`                 | `GL_TRUE` or `GL_FALSE` |
 | `GLFW_DECORATED`             | `GL_TRUE`                 | `GL_TRUE` or `GL_FALSE` |
 | `GLFW_AUTO_ICONIFY`          | `GL_TRUE`                 | `GL_TRUE` or `GL_FALSE` |
+| `GLFW_FLOATING`              | `GL_FALSE`                | `GL_TRUE` or `GL_FALSE` |
 | `GLFW_RED_BITS`              | 8                         | 0 to `INT_MAX` or `GLFW_DONT_CARE` |
 | `GLFW_GREEN_BITS`            | 8                         | 0 to `INT_MAX` or `GLFW_DONT_CARE` |
 | `GLFW_BLUE_BITS`             | 8                         | 0 to `INT_MAX` or `GLFW_DONT_CARE` |
@@ -445,6 +451,10 @@ The `GLFW_DECORATED` attribute indicates whether the specified window has
 decorations such as a border, a close widget, etc.  This is controlled by the
 [window hint](@ref window_hints) with the same name. 
 
+The `GLFW_FLOATING` attribute indicates whether the specified window is
+floating, also called topmost or always-on-top.  This is controlled by the
+[window hint](@ref window_hints) with the same name. 
+
 
 @subsection window_attribs_context Context attributes
 

include/GLFW/glfw3.h

@@ -498,6 +498,7 @@ extern "C" {
 #define GLFW_VISIBLE                0x00020004
 #define GLFW_DECORATED              0x00020005
 #define GLFW_AUTO_ICONIFY           0x00020006
+#define GLFW_FLOATING               0x00020007
 
 #define GLFW_RED_BITS               0x00021001
 #define GLFW_GREEN_BITS             0x00021002

src/cocoa_window.m

@@ -972,6 +972,9 @@ static GLboolean createWindow(_GLFWwindow* window,
     }
 #endif /*MAC_OS_X_VERSION_MAX_ALLOWED*/
 
+    if (wndconfig->floating)
+        [window->ns.object setLevel:NSFloatingWindowLevel];
+
     [window->ns.object setTitle:[NSString stringWithUTF8String:wndconfig->title]];
     [window->ns.object setContentView:window->ns.view];
     [window->ns.object setDelegate:window->ns.delegate];

src/internal.h

@@ -153,6 +153,7 @@ struct _GLFWwndconfig
     GLboolean     visible;
     GLboolean     decorated;
     GLboolean     autoIconify;
+    GLboolean     floating;
     _GLFWmonitor* monitor;
 };
 
@@ -218,6 +219,7 @@ struct _GLFWwindow
     GLboolean           resizable;
     GLboolean           decorated;
     GLboolean           autoIconify;
+    GLboolean           floating;
     GLboolean           visible;
     GLboolean           closed;
     void*               userPointer;
@@ -323,6 +325,7 @@ struct _GLFWlibrary
         int         visible;
         int         decorated;
         int         autoIconify;
+        int         floating;
         int         samples;
         int         sRGB;
         int         refreshRate;

src/win32_window.c

@@ -951,6 +951,14 @@ static int createWindow(_GLFWwindow* window,
                                           WM_COPYGLOBALDATA, MSGFLT_ALLOW, NULL);
     }
 
+    if (wndconfig->floating && !wndconfig->monitor)
+    {
+        SetWindowPos(window->win32.handle,
+                        HWND_TOPMOST,
+                        0, 0, 0, 0,
+                        SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE);
+    }
+
     DragAcceptFiles(window->win32.handle, TRUE);
 
     if (!_glfwCreateContext(window, ctxconfig, fbconfig))

src/window.c

@@ -167,6 +167,7 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
     wndconfig.visible       = _glfw.hints.visible ? GL_TRUE : GL_FALSE;
     wndconfig.decorated     = _glfw.hints.decorated ? GL_TRUE : GL_FALSE;
     wndconfig.autoIconify   = _glfw.hints.autoIconify ? GL_TRUE : GL_FALSE;
+    wndconfig.floating      = _glfw.hints.floating ? GL_TRUE : GL_FALSE;
     wndconfig.monitor       = (_GLFWmonitor*) monitor;
 
     // Set up desired context config
@@ -205,6 +206,7 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
     window->resizable   = wndconfig.resizable;
     window->decorated   = wndconfig.decorated;
     window->autoIconify = wndconfig.autoIconify;
+    window->floating    = wndconfig.floating;
     window->cursorMode  = GLFW_CURSOR_NORMAL;
 
     // Save the currently current context so it can be restored later
@@ -335,6 +337,9 @@ GLFWAPI void glfwWindowHint(int target, int hint)
         case GLFW_AUTO_ICONIFY:
             _glfw.hints.autoIconify = hint;
             break;
+        case GLFW_FLOATING:
+            _glfw.hints.floating = hint;
+            break;
         case GLFW_VISIBLE:
             _glfw.hints.visible = hint;
             break;
@@ -585,6 +590,8 @@ GLFWAPI int glfwGetWindowAttrib(GLFWwindow* handle, int attrib)
             return window->resizable;
         case GLFW_DECORATED:
             return window->decorated;
+        case GLFW_FLOATING:
+            return window->floating;
         case GLFW_VISIBLE:
             return window->visible;
         case GLFW_CLIENT_API:

src/x11_init.c

@@ -419,6 +419,8 @@ static void detectEWMH(void)
     // See which of the atoms we support that are supported by the WM
     _glfw.x11.NET_WM_STATE =
         getSupportedAtom(supportedAtoms, atomCount, "_NET_WM_STATE");
+    _glfw.x11.NET_WM_STATE_ABOVE =
+        getSupportedAtom(supportedAtoms, atomCount, "_NET_WM_STATE_ABOVE");
     _glfw.x11.NET_WM_STATE_FULLSCREEN =
         getSupportedAtom(supportedAtoms, atomCount, "_NET_WM_STATE_FULLSCREEN");
     _glfw.x11.NET_WM_NAME =

src/x11_platform.h

@@ -122,6 +122,7 @@ typedef struct _GLFWlibraryX11
     Atom            NET_WM_PID;
     Atom            NET_WM_PING;
     Atom            NET_WM_STATE;
+    Atom            NET_WM_STATE_ABOVE;
     Atom            NET_WM_STATE_FULLSCREEN;
     Atom            NET_WM_BYPASS_COMPOSITOR;
     Atom            NET_ACTIVE_WINDOW;

src/x11_window.c

@@ -108,6 +108,29 @@ static int translateChar(XKeyEvent* event)
     return (int) _glfwKeySym2Unicode(keysym);
 }
 
+// Adds or removes an EWMH state to a window
+//
+static void changeWindowState(_GLFWwindow* window, Atom state, int action)
+{
+    XEvent event;
+    memset(&event, 0, sizeof(event));
+
+    event.type = ClientMessage;
+    event.xclient.window = window->x11.handle;
+    event.xclient.format = 32; // Data is 32-bit longs
+    event.xclient.message_type = _glfw.x11.NET_WM_STATE;
+    event.xclient.data.l[0] = action;
+    event.xclient.data.l[1] = state;
+    event.xclient.data.l[2] = 0; // No secondary property
+    event.xclient.data.l[3] = 1; // Sender is a normal application
+
+    XSendEvent(_glfw.x11.display,
+               _glfw.x11.root,
+               False,
+               SubstructureNotifyMask | SubstructureRedirectMask,
+               &event);
+}
+
 // Splits and translates a text/uri-list into separate file paths
 //
 static char** parseUriList(char* text, int* count)
@@ -382,6 +405,16 @@ static GLboolean createWindow(_GLFWwindow* window,
         XIfEvent(_glfw.x11.display, &event, isFrameExtentsEvent, (XPointer) window);
     }
 
+    if (wndconfig->floating && !wndconfig->monitor)
+    {
+        if (_glfw.x11.NET_WM_STATE && _glfw.x11.NET_WM_STATE_ABOVE)
+        {
+            changeWindowState(window,
+                              _glfw.x11.NET_WM_STATE_ABOVE,
+                              _NET_WM_STATE_ADD);
+        }
+    }
+
     _glfwPlatformSetWindowTitle(window, wndconfig->title);
 
     XRRSelectInput(_glfw.x11.display, window->x11.handle,
@@ -490,23 +523,9 @@ static void enterFullscreenMode(_GLFWwindow* window)
         // Fullscreen windows are undecorated and, when focused, are kept
         // on top of all other windows
 
-        XEvent event;
-        memset(&event, 0, sizeof(event));
-
-        event.type = ClientMessage;
-        event.xclient.window = window->x11.handle;
-        event.xclient.format = 32; // Data is 32-bit longs
-        event.xclient.message_type = _glfw.x11.NET_WM_STATE;
-        event.xclient.data.l[0] = _NET_WM_STATE_ADD;
-        event.xclient.data.l[1] = _glfw.x11.NET_WM_STATE_FULLSCREEN;
-        event.xclient.data.l[2] = 0; // No secondary property
-        event.xclient.data.l[3] = 1; // Sender is a normal application
-
-        XSendEvent(_glfw.x11.display,
-                   _glfw.x11.root,
-                   False,
-                   SubstructureNotifyMask | SubstructureRedirectMask,
-                   &event);
+        changeWindowState(window,
+                          _glfw.x11.NET_WM_STATE_FULLSCREEN,
+                          _NET_WM_STATE_ADD);
     }
     else if (window->x11.overrideRedirect)
     {
@@ -557,23 +576,9 @@ static void leaveFullscreenMode(_GLFWwindow* window)
         // Ask the window manager to make the GLFW window a normal window
         // Normal windows usually have frames and other decorations
 
-        XEvent event;
-        memset(&event, 0, sizeof(event));
-
-        event.type = ClientMessage;
-        event.xclient.window = window->x11.handle;
-        event.xclient.format = 32; // Data is 32-bit longs
-        event.xclient.message_type = _glfw.x11.NET_WM_STATE;
-        event.xclient.data.l[0] = _NET_WM_STATE_REMOVE;
-        event.xclient.data.l[1] = _glfw.x11.NET_WM_STATE_FULLSCREEN;
-        event.xclient.data.l[2] = 0; // No secondary property
-        event.xclient.data.l[3] = 1; // Sender is a normal application
-
-        XSendEvent(_glfw.x11.display,
-                   _glfw.x11.root,
-                   False,
-                   SubstructureNotifyMask | SubstructureRedirectMask,
-                   &event);
+        changeWindowState(window,
+                          _glfw.x11.NET_WM_STATE_FULLSCREEN,
+                          _NET_WM_STATE_REMOVE);
     }
 }