Initial implementation of experimental gamma ramp API.

CMakeLists.txt

@@ -20,6 +20,7 @@ set(common_SOURCES
     ${GLFW_SOURCE_DIR}/src/enable.c 
     ${GLFW_SOURCE_DIR}/src/error.c
     ${GLFW_SOURCE_DIR}/src/fullscreen.c
+    ${GLFW_SOURCE_DIR}/src/gamma.c
     ${GLFW_SOURCE_DIR}/src/glext.c 
     ${GLFW_SOURCE_DIR}/src/init.c 
     ${GLFW_SOURCE_DIR}/src/input.c 
@@ -67,14 +68,12 @@ if (UNIX AND NOT APPLE AND NOT CYGWIN)
     endif(X11_XRANDR_FOUND)
 
     # Check for Xf86VidMode (fallback legacy resolution switching extension)
-    if (NOT X11_XRANDR_FOUND)
     CHECK_X11_XF86VIDMODE()
     if (X11_XF86VIDMODE_FOUND)
         set(_GLFW_HAS_XF86VIDMODE 1)
         list(APPEND GLFW_INCLUDE_DIR ${X11_XF86VIDMODE_INCLUDE_DIR})
         list(APPEND GLFW_LIBRARIES ${X11_XF86VIDMODE_LIBRARIES})
     endif(X11_XF86VIDMODE_FOUND) 
-    endif (NOT X11_XRANDR_FOUND)
 
     CHECK_FUNCTION_EXISTS(glXGetProcAddress _GLFW_HAS_GLXGETPROCADDRESS)
 

include/GL/glfw3.h

@@ -361,6 +361,8 @@ extern "C" {
 #define GLFW_VERSION_UNAVAILABLE  0x00070007
 #define GLFW_PLATFORM_ERROR       0x00070008
 
+/* Gamma ramps */
+#define GLFW_GAMMA_RAMP_SIZE      256
 
 /*************************************************************************
  * Typedefs
@@ -379,6 +381,14 @@ typedef struct
     int greenBits;
 } GLFWvidmode;
 
+/* Gamma ramp */
+typedef struct
+{
+    unsigned short red[GLFW_GAMMA_RAMP_SIZE];
+    unsigned short green[GLFW_GAMMA_RAMP_SIZE];
+    unsigned short blue[GLFW_GAMMA_RAMP_SIZE];
+} GLFWgammaramp;
+
 /* Function pointer types */
 typedef void (* GLFWwindowsizefun)(GLFWwindow,int,int);
 typedef int  (* GLFWwindowclosefun)(GLFWwindow);
@@ -410,6 +420,11 @@ GLFWAPI const char* glfwErrorString(int error);
 GLFWAPI int  glfwGetVideoModes(GLFWvidmode* list, int maxcount);
 GLFWAPI void glfwGetDesktopMode(GLFWvidmode* mode);
 
+/* Gamma ramp functions */
+GLFWAPI void glfwSetGammaFormula(float gamma, float blacklevel, float gain);
+GLFWAPI void glfwGetGammaRamp(GLFWgammaramp* ramp);
+GLFWAPI void glfwSetGammaRamp(const GLFWgammaramp* ramp);
+
 /* Window handling */
 GLFWAPI GLFWwindow glfwOpenWindow(int width, int height, int mode, const char* title, GLFWwindow share);
 GLFWAPI void glfwOpenWindowHint(int target, int hint);

readme.html

@@ -802,6 +802,9 @@ their skills.  Special thanks go out to:</p>
   <li>Jonathan Dummer, for submitting a patch fixing an input bug on Win32 and
   adding logic for the <code>GLFW_ICON</code> resource</li>
 
+  <li>Ralph Eastwood, for the initial design of the gamma correction API and
+  the Win32 and X11 implementations of it</li>
+
   <li>Gerald Franz, who made GLFW compile under IRIX, and supplied patches
   for the X11 keyboard translation routine</li>
 

src/gamma.c

@@ -0,0 +1,115 @@
+//========================================================================
+// GLFW - An OpenGL framework
+// Platform:    Any
+// API version: 3.0
+// WWW:         http://www.glfw.org/
+//------------------------------------------------------------------------
+// Copyright (c) 2010 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.
+//
+//========================================================================
+
+#include "internal.h"
+
+#include <math.h>
+#include <string.h>
+
+
+//////////////////////////////////////////////////////////////////////////
+//////                        GLFW public API                       //////
+//////////////////////////////////////////////////////////////////////////
+
+//========================================================================
+// Calculate the gamma ramp table from specified values
+//========================================================================
+
+GLFWAPI void glfwSetGammaFormula(float gamma, float blacklevel, float gain)
+{
+    int i, size = 256;
+    GLFWgammaramp ramp;
+
+    if (!_glfwInitialized)
+    {
+        _glfwSetError(GLFW_NOT_INITIALIZED);
+        return;
+    }
+
+    for (i = 0;  i < size;  i++)
+    {
+        float value = (float) i / ((float) (size - 1));
+
+        // Apply gamma
+        value = pow(value, gamma) * 65535.f + 0.5f;
+
+        // Apply gain
+        value = gain * (value - 32767.5f) + 32767.5f;
+
+        // Apply black-level
+        value += blacklevel * 65535.f;
+
+        // Clamp values
+        if (value < 0.f)
+            value = 0.f;
+        else if (value > 65535.f)
+            value = 65535.f;
+
+        // Set the gamma ramp values
+        ramp.red[i]   = (unsigned short) value;
+        ramp.green[i] = (unsigned short) value;
+        ramp.blue[i]  = (unsigned short) value;
+    }
+
+    glfwSetGammaRamp(&ramp);
+}
+
+
+//========================================================================
+// Return the currently set gamma ramp
+//========================================================================
+
+GLFWAPI void glfwGetGammaRamp(GLFWgammaramp* ramp)
+{
+    if (!_glfwInitialized)
+    {
+        _glfwSetError(GLFW_NOT_INITIALIZED);
+        return;
+    }
+
+    *ramp = _glfwLibrary.currentRamp;
+}
+
+
+//========================================================================
+// Make the specified gamma ramp current
+//========================================================================
+
+GLFWAPI void glfwSetGammaRamp(const GLFWgammaramp* ramp)
+{
+    if (!_glfwInitialized)
+    {
+        _glfwSetError(GLFW_NOT_INITIALIZED);
+        return;
+    }
+
+    _glfwPlatformSetGammaRamp(ramp);
+    _glfwLibrary.currentRamp = *ramp;
+}
+

src/internal.h

@@ -222,6 +222,10 @@ struct _GLFWlibrary
     _GLFWwindow*  activeWindow;
     _GLFWwindow*  cursorLockWindow;
 
+    GLFWgammaramp currentRamp;
+    GLFWgammaramp originalRamp;
+    int           originalRampSize;
+
     _GLFW_PLATFORM_LIBRARY_STATE;
 };
 
@@ -257,6 +261,10 @@ void _glfwPlatformDisableSystemKeys(_GLFWwindow* window);
 int  _glfwPlatformGetVideoModes(GLFWvidmode* list, int maxcount);
 void _glfwPlatformGetDesktopMode(GLFWvidmode* mode);
 
+// Gamma ramp
+void _glfwPlatformSaveGammaRamp(void);
+void _glfwPlatformSetGammaRamp(const GLFWgammaramp* ramp);
+
 // Joystick
 int _glfwPlatformGetJoystickParam(int joy, int param);
 int _glfwPlatformGetJoystickPos(int joy, float* pos, int numaxes);

src/win32/CMakeLists.txt

@@ -23,6 +23,7 @@ set(libglfw_SOURCES
     ${common_SOURCES}
     win32_enable.c 
     win32_fullscreen.c
+    win32_gamma.c
     win32_glext.c
     win32_init.c 
     win32_joystick.c

src/win32/platform.h

@@ -156,6 +156,8 @@ typedef int  (WINAPI * DESCRIBEPIXELFORMAT_T) (HDC,int,UINT,LPPIXELFORMATDESCRIP
 typedef int  (WINAPI * GETPIXELFORMAT_T) (HDC);
 typedef BOOL (WINAPI * SETPIXELFORMAT_T) (HDC,int,const PIXELFORMATDESCRIPTOR*);
 typedef BOOL (WINAPI * SWAPBUFFERS_T) (HDC);
+typedef BOOL (WINAPI * GETDEVICEGAMMARAMP_T) (HDC,PVOID);
+typedef BOOL (WINAPI * SETDEVICEGAMMARAMP_T) (HDC,PVOID);
 #endif // _GLFW_NO_DLOAD_GDI32
 
 // winmm.dll function pointer typedefs
@@ -174,12 +176,16 @@ typedef DWORD (WINAPI * TIMEGETTIME_T) (void);
 #define _glfw_GetPixelFormat      _glfwLibrary.Win32.gdi.GetPixelFormat
 #define _glfw_SetPixelFormat      _glfwLibrary.Win32.gdi.SetPixelFormat
 #define _glfw_SwapBuffers         _glfwLibrary.Win32.gdi.SwapBuffers
+#define _glfw_GetDeviceGammaRamp  _glfwLibrary.Win32.gdi.GetDeviceGammaRamp
+#define _glfw_SetDeviceGammaRamp  _glfwLibrary.Win32.gdi.SetDeviceGammaRamp
 #else
 #define _glfw_ChoosePixelFormat   ChoosePixelFormat
 #define _glfw_DescribePixelFormat DescribePixelFormat
 #define _glfw_GetPixelFormat      GetPixelFormat
 #define _glfw_SetPixelFormat      SetPixelFormat
 #define _glfw_SwapBuffers         SwapBuffers
+#define _glfw_GetDeviceGammaRamp  GetDeviceGammaRamp
+#define _glfw_SetDeviceGammaRamp  SetDeviceGammaRamp
 #endif // _GLFW_NO_DLOAD_GDI32
 
 // winmm.dll shortcuts
@@ -264,6 +270,7 @@ typedef struct _GLFWlibraryWin32
     ATOM      classAtom;       // Window class atom
     HHOOK     keyboardHook;    // Keyboard hook handle
     DWORD     foregroundLockTimeout;
+    HDC       desktopDC;
 
     // Default monitor
     struct {
@@ -291,6 +298,8 @@ typedef struct _GLFWlibraryWin32
         GETPIXELFORMAT_T      GetPixelFormat;
         SETPIXELFORMAT_T      SetPixelFormat;
         SWAPBUFFERS_T         SwapBuffers;
+        GETDEVICEGAMMARAMP_T  GetDeviceGammaRamp;
+        SETDEVICEGAMMARAMP_T  SetDeviceGammaRamp;
     } gdi;
 #endif // _GLFW_NO_DLOAD_GDI32
 

src/win32/win32_gamma.c

@@ -0,0 +1,67 @@
+//========================================================================
+// GLFW - An OpenGL framework
+// Platform:    Win32/WGL
+// API version: 2.7
+// WWW:         http://www.glfw.org/
+//------------------------------------------------------------------------
+// Copyright (c) 2002-2006 Marcus Geelnard
+// Copyright (c) 2006-2010 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.
+//
+//========================================================================
+
+#include "internal.h"
+
+#include <limits.h>
+
+
+//************************************************************************
+//****                  GLFW internal functions                       ****
+//************************************************************************
+
+//========================================================================
+// Save the gamma ramp to our internal copy
+//========================================================================
+
+void _glfwPlatformSaveGammaRamp(int ramp)
+{
+    if (!_glfwLibrary.gammaSize)
+    {
+        return;
+    }
+    _glfw_GetDeviceGammaRamp(_glfwLibrary.Win32.desktopDC,
+                             _glfwLibrary.gammaRamp[ramp]);
+}
+
+
+//========================================================================
+// Restore the gamma ramp to our internal copy of the gamma ramp
+//========================================================================
+
+void _glfwPlatformRestoreGammaRamp(int ramp)
+{
+    if (!_glfwLibrary.gammaSize)
+    {
+        return;
+    }
+    _glfw_SetDeviceGammaRamp(_glfwLibrary.Win32.desktopDC,
+                             _glfwLibrary.gammaRamp[ramp]);
+}

src/win32/win32_init.c

@@ -30,6 +30,8 @@
 
 #include "internal.h"
 
+#include <stdlib.h>
+
 #ifdef __BORLANDC__
 // With the Borland C++ compiler, we want to disable FPU exceptions
 #include <float.h>
@@ -59,12 +61,18 @@ static GLboolean initLibraries(void)
         GetProcAddress(_glfwLibrary.Win32.gdi.instance, "SetPixelFormat");
     _glfwLibrary.Win32.gdi.SwapBuffers = (SWAPBUFFERS_T)
         GetProcAddress(_glfwLibrary.Win32.gdi.instance, "SwapBuffers");
+    _glfwLibrary.Win32.gdi.GetDeviceGammaRamp  = (GETDEVICEGAMMARAMP_T)
+        GetProcAddress(_glfwLibrary.Win32.gdi.instance, "GetDeviceGammaRamp");
+    _glfwLibrary.Win32.gdi.SetDeviceGammaRamp  = (SETDEVICEGAMMARAMP_T)
+        GetProcAddress(_glfwLibrary.Win32.gdi.instance, "SetDeviceGammaRamp");
 
     if (!_glfwLibrary.Win32.gdi.ChoosePixelFormat ||
         !_glfwLibrary.Win32.gdi.DescribePixelFormat ||
         !_glfwLibrary.Win32.gdi.GetPixelFormat ||
         !_glfwLibrary.Win32.gdi.SetPixelFormat ||
-        !_glfwLibrary.Win32.gdi.SwapBuffers)
+        !_glfwLibrary.Win32.gdi.SwapBuffers ||
+        !_glfwLibrary.Win32.gdi.GetDeviceGammaRamp ||
+        !_glfwLibrary.Win32.gdi.SetDeviceGammaRamp)
     {
         return GL_FALSE;
     }
@@ -152,6 +160,19 @@ int _glfwPlatformInit(void)
 
     _glfwLibrary.Win32.instance = GetModuleHandle(NULL);
 
+    // Initialise the internal gamma ramp
+    _glfwLibrary.gammaSize = 256;
+    _glfwLibrary.gammaRamp[GLFW_GAMMA_ORIG] =
+        malloc(256 * sizeof(unsigned short) * 3);
+    _glfwLibrary.gammaRamp[GLFW_GAMMA_CURR] =
+        malloc(256 * sizeof(unsigned short) * 3);
+
+    // Get the desktop DC
+    _glfwLibrary.Win32.desktopDC = GetDC(GetDesktopWindow());
+
+    // Save the original gamma ramp
+    _glfwPlatformSaveGammaRamp(GLFW_GAMMA_ORIG);
+
     _glfwInitTimer();
 
     return GL_TRUE;
@@ -164,6 +185,13 @@ int _glfwPlatformInit(void)
 
 int _glfwPlatformTerminate(void)
 {
+    // Restore the original gamma ramp
+    _glfwPlatformRestoreGammaRamp(GLFW_GAMMA_ORIG);
+
+    // Free the gamma ramps
+    free(_glfwLibrary.gammaRamp[GLFW_GAMMA_ORIG]);
+    free(_glfwLibrary.gammaRamp[GLFW_GAMMA_CURR]);
+
     if (_glfwLibrary.Win32.classAtom)
     {
         UnregisterClass(_GLFW_WNDCLASSNAME, _glfwLibrary.Win32.instance);

src/x11/CMakeLists.txt

@@ -12,6 +12,7 @@ set(libglfw_SOURCES
     ${common_SOURCES}
     x11_enable.c 
     x11_fullscreen.c
+    x11_gamma.c
     x11_glext.c
     x11_init.c 
     x11_joystick.c

src/x11/platform.h

@@ -52,10 +52,6 @@
  #error "GLX header version 1.3 or above is required"
 #endif
 
-#if defined(_GLFW_HAS_XF86VIDMODE) && defined(_GLFW_HAS_XRANDR)
- #error "Xf86VidMode and RandR extensions cannot both be enabled"
-#endif
-
 // With XFree86, we can use the XF86VidMode extension
 #if defined(_GLFW_HAS_XF86VIDMODE)
  #include <X11/extensions/xf86vmode.h>
@@ -156,15 +152,18 @@ typedef struct _GLFWlibraryX11
     int             glxMajor, glxMinor;
 
     struct {
-        int         available;
+        GLboolean   available;
         int         eventBase;
         int         errorBase;
     } XF86VidMode;
 
     struct {
-        int         available;
+        GLboolean   available;
         int         eventBase;
         int         errorBase;
+        int         majorVersion;
+        int         minorVersion;
+        GLboolean   gammaBroken;
     } XRandR;
 
     // Screensaver data
@@ -179,14 +178,13 @@ typedef struct _GLFWlibraryX11
     // Fullscreen data
     struct {
         int     modeChanged;
-#if defined(_GLFW_HAS_XF86VIDMODE)
-        XF86VidModeModeInfo oldMode;
-#endif
 #if defined(_GLFW_HAS_XRANDR)
         SizeID   oldSizeID;
         int      oldWidth;
         int      oldHeight;
         Rotation oldRotation;
+#elif defined(_GLFW_HAS_XF86VIDMODE)
+        XF86VidModeModeInfo oldMode;
 #endif
     } FS;
 

src/x11/x11_fullscreen.c

@@ -480,7 +480,7 @@ void _glfwPlatformGetDesktopMode(GLFWvidmode* mode)
 {
     Display* dpy;
     int bpp, screen;
-#if defined(_GLFW_HAS_XF86VIDMODE)
+#if !defined(_GLFW_HAS_XRANDR) && defined(_GLFW_HAS_XF86VIDMODE)
     XF86VidModeModeInfo** modelist;
     int modecount;
 #endif

src/x11/x11_gamma.c

@@ -0,0 +1,124 @@
+//========================================================================
+// GLFW - An OpenGL framework
+// Platform:    X11/GLX
+// API version: 3.0
+// WWW:         http://www.glfw.org/
+//------------------------------------------------------------------------
+// Copyright (c) 2010 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.
+//
+//========================================================================
+
+#include "internal.h"
+
+#include <limits.h>
+#include <string.h>
+
+
+//************************************************************************
+//****                  GLFW internal functions                       ****
+//************************************************************************
+
+//========================================================================
+// Save the original gamma ramp so that we can restore it later
+//========================================================================
+
+void _glfwPlatformSaveGammaRamp(void)
+{
+    if (_glfwLibrary.X11.XRandR.available &&
+        !_glfwLibrary.X11.XRandR.gammaBroken)
+    {
+#if defined (_GLFW_HAS_XRANDR)
+        size_t size = GLFW_GAMMA_RAMP_SIZE * sizeof(unsigned short);
+
+        XRRScreenResources* rr = XRRGetScreenResources(_glfwLibrary.X11.display,
+                                                       _glfwLibrary.X11.root);
+
+        XRRCrtcGamma* gamma = XRRGetCrtcGamma(_glfwLibrary.X11.display,
+                                              rr->crtcs[0]);
+
+        memcpy(_glfwLibrary.originalRamp.red, gamma->red, size);
+        memcpy(_glfwLibrary.originalRamp.green, gamma->green, size);
+        memcpy(_glfwLibrary.originalRamp.blue, gamma->blue, size);
+
+        XRRFreeGamma(gamma);
+        XRRFreeScreenResources(rr);
+    }
+#endif
+    else if (_glfwLibrary.X11.XF86VidMode.available)
+    {
+#if defined (_GLFW_HAS_XF86VIDMODE)
+        XF86VidModeGetGammaRamp(_glfwLibrary.X11.display,
+                                _glfwLibrary.X11.screen,
+                                GLFW_GAMMA_RAMP_SIZE,
+                                _glfwLibrary.originalRamp.red,
+                                _glfwLibrary.originalRamp.green,
+                                _glfwLibrary.originalRamp.blue);
+#endif
+    }
+}
+
+
+//========================================================================
+// Make the specified gamma ramp current
+//========================================================================
+
+void _glfwPlatformSetGammaRamp(const GLFWgammaramp* ramp)
+{
+    if (_glfwLibrary.X11.XRandR.available &&
+        !_glfwLibrary.X11.XRandR.gammaBroken)
+    {
+#if defined (_GLFW_HAS_XRANDR)
+        int i;
+        size_t size = GLFW_GAMMA_RAMP_SIZE * sizeof(unsigned short);
+
+        XRRScreenResources* rr = XRRGetScreenResources(_glfwLibrary.X11.display,
+                                                       _glfwLibrary.X11.root);
+
+        // Update gamma per monitor
+        for (i = 0;  i < rr->ncrtc;  i++)
+        {
+            XRRCrtcGamma* gamma = XRRAllocGamma(GLFW_GAMMA_RAMP_SIZE);
+
+            memcpy(gamma->red, ramp->red, size);
+            memcpy(gamma->green, ramp->green, size);
+            memcpy(gamma->blue, ramp->blue, size);
+
+            XRRSetCrtcGamma(_glfwLibrary.X11.display, rr->crtcs[i], gamma);
+            XRRFreeGamma(gamma);
+        }
+
+        XRRFreeScreenResources(rr);
+    }
+#endif
+    else if (_glfwLibrary.X11.XF86VidMode.available)
+    {
+#if defined (_GLFW_HAS_XF86VIDMODE)
+        XF86VidModeSetGammaRamp(_glfwLibrary.X11.display,
+                                _glfwLibrary.X11.screen,
+                                GLFW_GAMMA_RAMP_SIZE,
+                                (unsigned short*) ramp->red,
+                                (unsigned short*) ramp->green,
+                                (unsigned short*) ramp->blue);
+#endif
+    }
+}
+

src/x11/x11_init.c

@@ -31,6 +31,7 @@
 #include "internal.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 
 
 //========================================================================
@@ -62,7 +63,7 @@ static void initLibraries(void)
 
 
 //========================================================================
-// Initialize X11 display
+// Initialize X11 display and look for supported X11 extensions
 //========================================================================
 
 static GLboolean initDisplay(void)
@@ -88,7 +89,7 @@ static GLboolean initDisplay(void)
                                   &_glfwLibrary.X11.XF86VidMode.eventBase,
                                   &_glfwLibrary.X11.XF86VidMode.errorBase);
 #else
-    _glfwLibrary.X11.XF86VidMode.available = 0;
+    _glfwLibrary.X11.XF86VidMode.available = GL_FALSE;
 #endif
 
     // Check for XRandR extension
@@ -97,11 +98,17 @@ static GLboolean initDisplay(void)
         XRRQueryExtension(_glfwLibrary.X11.display,
                           &_glfwLibrary.X11.XRandR.eventBase,
                           &_glfwLibrary.X11.XRandR.errorBase);
+
+    if (!XRRQueryVersion(_glfwLibrary.X11.display,
+                        &_glfwLibrary.X11.XRandR.majorVersion,
+                        &_glfwLibrary.X11.XRandR.minorVersion))
+    {
+        fprintf(stderr, "Unable to query RandR version number\n");
+    }
 #else
-    _glfwLibrary.X11.XRandR.available = 0;
+    _glfwLibrary.X11.XRandR.available = GL_FALSE;
 #endif
 
-    // Fullscreen & screen saver settings
     // Check if GLX is supported on this display
     if (!glXQueryExtension(_glfwLibrary.X11.display, NULL, NULL))
     {
@@ -123,6 +130,58 @@ static GLboolean initDisplay(void)
 }
 
 
+//========================================================================
+// Detect gamma ramp support and save original gamma ramp, if available
+//========================================================================
+
+static void initGammaRamp(void)
+{
+#ifdef _GLFW_HAS_XRANDR
+    // RandR gamma support is only available with version 1.2 and above
+    if (_glfwLibrary.X11.XRandR.available &&
+        (_glfwLibrary.X11.XRandR.majorVersion > 1 ||
+         _glfwLibrary.X11.XRandR.majorVersion == 1 &&
+         _glfwLibrary.X11.XRandR.minorVersion >= 2))
+    {
+        // FIXME: Assumes that all monitors have the same size gamma tables
+        // This is reasonable as I suspect the that if they did differ, it
+        // would imply that setting the gamma size to an arbitary size is
+        // possible as well.
+        XRRScreenResources* rr = XRRGetScreenResources(_glfwLibrary.X11.display,
+                                                       _glfwLibrary.X11.root);
+
+        _glfwLibrary.originalRampSize = XRRGetCrtcGammaSize(_glfwLibrary.X11.display,
+                                                            rr->crtcs[0]);
+        if (!_glfwLibrary.originalRampSize)
+        {
+            // This is probably Nvidia RandR with broken gamma support
+            // Flag it as useless and try Xf86VidMode below, if available
+            _glfwLibrary.X11.XRandR.gammaBroken = GL_TRUE;
+        }
+
+        XRRFreeScreenResources(rr);
+    }
+#endif
+
+#if defined(_GLFW_HAS_XF86VIDMODE)
+    if (_glfwLibrary.X11.XF86VidMode.available &&
+        !_glfwLibrary.originalRampSize)
+    {
+        // Get the gamma size using XF86VidMode
+        XF86VidModeGetGammaRampSize(_glfwLibrary.X11.display,
+                                    _glfwLibrary.X11.screen,
+                                    &_glfwLibrary.originalRampSize);
+    }
+#endif
+
+    if (!_glfwLibrary.originalRampSize)
+        fprintf(stderr, "Gamma ramp setting unsupported\n");
+
+    // Save the original gamma ramp
+    _glfwPlatformSaveGammaRamp();
+}
+
+
 //========================================================================
 // Create a blank cursor (for locked mouse mode)
 //========================================================================
@@ -159,8 +218,15 @@ static Cursor createNULLCursor(void)
 
 static void terminateDisplay(void)
 {
+    if (_glfwLibrary.originalRampSize)
+    {
+        _glfwPlatformSetGammaRamp(&_glfwLibrary.originalRamp);
+    }
+
     if (_glfwLibrary.X11.display)
     {
+        _glfwPlatformSetGammaRamp(&_glfwLibrary.originalRamp);
+
         XCloseDisplay(_glfwLibrary.X11.display);
         _glfwLibrary.X11.display = NULL;
     }
@@ -180,6 +246,8 @@ int _glfwPlatformInit(void)
     if (!initDisplay())
         return GL_FALSE;
 
+    initGammaRamp();
+
     _glfwLibrary.X11.cursor = createNULLCursor();
 
     // Try to load libGL.so if necessary
@@ -232,7 +300,8 @@ const char* _glfwPlatformGetVersionString(void)
     const char* version = "GLFW " _GLFW_VERSION_FULL
 #if defined(_GLFW_HAS_XRANDR)
         " XRandR"
-#elif defined(_GLFW_HAS_XF86VIDMODE)
+#endif
+#if defined(_GLFW_HAS_XF86VIDMODE)
         " Xf86VidMode"
 #else
         " (no mode switching support)"

tests/CMakeLists.txt

@@ -6,6 +6,7 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../include ${OPENGL_INCLUDE_DIR}
 add_executable(defaults defaults.c)
 add_executable(events events.c)
 add_executable(fsfocus fsfocus.c)
+add_executable(gamma gamma.c getopt.c)
 add_executable(iconify iconify.c getopt.c)
 add_executable(joysticks joysticks.c)
 add_executable(listmodes listmodes.c)
@@ -30,8 +31,8 @@ else()
 endif(APPLE)
 
 set(WINDOWS_BINARIES accuracy sharing tearing windows)
-set(CONSOLE_BINARIES defaults events fsaa fsfocus iconify joysticks listmodes
+set(CONSOLE_BINARIES defaults events fsaa fsfocus gamma iconify joysticks
-                     peter reopen version)
+                     listmodes peter reopen version)
 
 if(MSVC)
   # Tell MSVC to use main instead of WinMain for Windows subsystem executables

tests/gamma.c

@@ -0,0 +1,178 @@
+//========================================================================
+// Gamma correction 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 gamma correction functionality for
+// both fullscreen and windowed mode windows
+//
+//========================================================================
+
+#include <GL/glfw3.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "getopt.h"
+
+static GLfloat ggamma = 1.0f;
+static GLfloat ggain = 1.0f;
+static GLfloat gblacklevel = 0.0f;
+
+static void usage(void)
+{
+    printf("Usage: gammatest [-h] [-f]\n");
+}
+
+static void key_callback(GLFWwindow window, int key, int action)
+{
+    if (action != GLFW_PRESS)
+        return;
+
+    switch (key)
+    {
+        case GLFW_KEY_ESC:
+            glfwCloseWindow(window);
+            break;
+        case 'Q':
+            ggamma += 0.1f;
+            printf("Gamma: %f\n", ggamma);
+            glfwSetGammaFormula( ggamma, gblacklevel, ggain );
+            break;
+        case 'W':
+            ggamma -= 0.1f;
+            printf("Gamma: %f\n", ggamma);
+            glfwSetGammaFormula( ggamma, gblacklevel, ggain );
+            break;
+        case 'A':
+            ggain += 0.1f;
+            printf("Gain: %f\n", ggain);
+            glfwSetGammaFormula( ggamma, gblacklevel, ggain );
+            break;
+        case 'S':
+            ggain -= 0.1f;
+            printf("Gain: %f\n", ggain);
+            glfwSetGammaFormula( ggamma, gblacklevel, ggain );
+            break;
+        case 'Z':
+            gblacklevel += 0.1f;
+            printf("Black Level: %f\n", gblacklevel);
+            glfwSetGammaFormula( ggamma, gblacklevel, ggain );
+            break;
+        case 'X':
+            gblacklevel -= 0.1f;
+            printf("Black Level: %f\n", gblacklevel);
+            glfwSetGammaFormula( ggamma, gblacklevel, ggain );
+            break;
+
+    }
+}
+
+static void size_callback(GLFWwindow window, int width, int height)
+{
+    glViewport(0, 0, width, height);
+}
+
+int main(int argc, char** argv)
+{
+    int width, height, ch;
+    int mode = GLFW_WINDOWED;
+    GLFWwindow window;
+
+    while ((ch = getopt(argc, argv, "fh")) != -1)
+    {
+        switch (ch)
+        {
+            case 'h':
+                usage();
+                exit(EXIT_SUCCESS);
+
+            case 'f':
+                mode = GLFW_FULLSCREEN;
+                break;
+
+            default:
+                usage();
+                exit(EXIT_FAILURE);
+        }
+    }
+
+    if (!glfwInit())
+    {
+        fprintf(stderr, "Failed to initialize GLFW: %s\n", glfwErrorString(glfwGetError()));
+        exit(EXIT_FAILURE);
+    }
+
+    if (mode == GLFW_FULLSCREEN)
+    {
+        GLFWvidmode mode;
+        glfwGetDesktopMode(&mode);
+        width = mode.width;
+        height = mode.height;
+    }
+    else
+    {
+        width = 0;
+        height = 0;
+    }
+
+    window = glfwOpenWindow(width, height, mode, "Gamma Test", NULL);
+    if (!window)
+    {
+        glfwTerminate();
+
+        fprintf(stderr, "Failed to open GLFW window: %s\n", glfwErrorString(glfwGetError()));
+        exit(EXIT_FAILURE);
+    }
+
+    printf("Gamma: %f\nGain: %f\nBlack Level: %f\n",
+           ggamma, ggain, gblacklevel);
+
+    glfwSwapInterval(1);
+    glfwSetKeyCallback(window, key_callback);
+    glfwSetWindowSizeCallback(window, size_callback);
+
+    glEnable(GL_SCISSOR_TEST);
+
+    while (glfwIsWindow(window))
+    {
+        int width, height;
+
+        glfwGetWindowSize(window, &width, &height);
+
+        glScissor(0, 0, width, height);
+        glClearColor(0.5f, 0.5f, 0.5f, 0);
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        glScissor(0, 0, 640, 480);
+        glClearColor(0.8f, 0.2f, 0.4f, 0);
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        glfwSwapBuffers();
+        glfwPollEvents();
+    }
+
+    glfwTerminate();
+    exit(EXIT_SUCCESS);
+}
+