More robust detection of support for GL_FRAMEBUFFER_SRGB

When not supported fallback to layer based rendering

glad/generate.py

@@ -10,7 +10,8 @@ import subprocess
 
 cmdline = (
     'glad --out-path {dest} --api gl:core=3.1 '
-    ' --extensions GL_ARB_texture_storage,GL_ARB_copy_image,GL_ARB_multisample,GL_ARB_robustness,GL_ARB_instanced_arrays,GL_KHR_debug '
+    ' --extensions GL_ARB_texture_storage,GL_ARB_copy_image,GL_ARB_multisample,GL_ARB_robustness,'
+    'GL_ARB_instanced_arrays,GL_KHR_debug,GL_ARB_framebuffer_sRGB,GL_EXT_framebuffer_sRGB '
     'c --header-only --debug'
 )
 

kitty/child-monitor.c

@@ -709,8 +709,10 @@ prepare_to_render_os_window(OSWindow *os_window, monotonic_t now, unsigned int *
 #define TD os_window->tab_bar_render_data
     bool needs_render = os_window->needs_render;
     os_window->needs_render = false;
-    os_window->needs_layers = os_window->is_semi_transparent || os_window->live_resize.in_progress || (
+    os_window->needs_layers = (
-            os_window->bgimage && os_window->bgimage->texture_id > 0);
+        !global_state.supports_framebuffer_srgb || os_window->is_semi_transparent ||
+        os_window->live_resize.in_progress || (os_window->bgimage && os_window->bgimage->texture_id > 0)
+    );
     if (TD.screen && os_window->num_tabs >= OPT(tab_bar_min_tabs)) {
         if (!os_window->tab_bar_data_updated) {
             call_boss(update_tab_bar_data, "K", os_window->id);

kitty/gl-wrapper.h

@@ -1,11 +1,11 @@
 /**
- * Loader generated by glad 2.0.8 on Mon Aug  4 08:35:54 2025
+ * Loader generated by glad 2.0.8 on Mon Aug 11 01:10:28 2025
  *
  * SPDX-License-Identifier: (WTFPL OR CC0-1.0) AND Apache-2.0
  *
  * Generator: C/C++
  * Specification: gl
- * Extensions: 6
+ * Extensions: 8
  *
  * APIs:
  *  - gl:core=3.1
@@ -19,10 +19,10 @@
  *  - ON_DEMAND = False
  *
  * Commandline:
- *    --api='gl:core=3.1' --extensions='GL_ARB_copy_image,GL_ARB_instanced_arrays,GL_ARB_multisample,GL_ARB_robustness,GL_ARB_texture_storage,GL_KHR_debug' c --debug --header-only
+ *    --api='gl:core=3.1' --extensions='GL_ARB_copy_image,GL_ARB_framebuffer_sRGB,GL_ARB_instanced_arrays,GL_ARB_multisample,GL_ARB_robustness,GL_ARB_texture_storage,GL_EXT_framebuffer_sRGB,GL_KHR_debug' c --debug --header-only
  *
  * Online:
- *    http://glad.sh/#api=gl%3Acore%3D3.1&extensions=GL_ARB_copy_image%2CGL_ARB_instanced_arrays%2CGL_ARB_multisample%2CGL_ARB_robustness%2CGL_ARB_texture_storage%2CGL_KHR_debug&generator=c&options=DEBUG%2CHEADER_ONLY
+ *    http://glad.sh/#api=gl%3Acore%3D3.1&extensions=GL_ARB_copy_image%2CGL_ARB_framebuffer_sRGB%2CGL_ARB_instanced_arrays%2CGL_ARB_multisample%2CGL_ARB_robustness%2CGL_ARB_texture_storage%2CGL_EXT_framebuffer_sRGB%2CGL_KHR_debug&generator=c&options=DEBUG%2CHEADER_ONLY
  *
  */
 #ifndef GLAD_GL_H_
@@ -561,6 +561,8 @@ typedef void (*GLADpostcallback)(void *ret, const char *name, GLADapiproc apipro
 #define GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE 0x8D56
 #define GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER 0x8CDC
 #define GL_FRAMEBUFFER_SRGB 0x8DB9
+#define GL_FRAMEBUFFER_SRGB_CAPABLE_EXT 0x8DBA
+#define GL_FRAMEBUFFER_SRGB_EXT 0x8DB9
 #define GL_FRAMEBUFFER_UNDEFINED 0x8219
 #define GL_FRAMEBUFFER_UNSUPPORTED 0x8CDD
 #define GL_FRONT 0x0404
@@ -1744,6 +1746,8 @@ GLAD_API_CALL int GLAD_GL_VERSION_3_0;
 GLAD_API_CALL int GLAD_GL_VERSION_3_1;
 #define GL_ARB_copy_image 1
 GLAD_API_CALL int GLAD_GL_ARB_copy_image;
+#define GL_ARB_framebuffer_sRGB 1
+GLAD_API_CALL int GLAD_GL_ARB_framebuffer_sRGB;
 #define GL_ARB_instanced_arrays 1
 GLAD_API_CALL int GLAD_GL_ARB_instanced_arrays;
 #define GL_ARB_multisample 1
@@ -1752,6 +1756,8 @@ GLAD_API_CALL int GLAD_GL_ARB_multisample;
 GLAD_API_CALL int GLAD_GL_ARB_robustness;
 #define GL_ARB_texture_storage 1
 GLAD_API_CALL int GLAD_GL_ARB_texture_storage;
+#define GL_EXT_framebuffer_sRGB 1
+GLAD_API_CALL int GLAD_GL_EXT_framebuffer_sRGB;
 #define GL_KHR_debug 1
 GLAD_API_CALL int GLAD_GL_KHR_debug;
 typedef void (GLAD_API_PTR *PFNGLACCUMPROC)(GLenum op, GLfloat value);
@@ -4478,10 +4484,12 @@ int GLAD_GL_VERSION_2_1 = 0;
 int GLAD_GL_VERSION_3_0 = 0;
 int GLAD_GL_VERSION_3_1 = 0;
 int GLAD_GL_ARB_copy_image = 0;
+int GLAD_GL_ARB_framebuffer_sRGB = 0;
 int GLAD_GL_ARB_instanced_arrays = 0;
 int GLAD_GL_ARB_multisample = 0;
 int GLAD_GL_ARB_robustness = 0;
 int GLAD_GL_ARB_texture_storage = 0;
+int GLAD_GL_EXT_framebuffer_sRGB = 0;
 int GLAD_GL_KHR_debug = 0;
 static void _pre_call_gl_callback_default(const char *name, GLADapiproc apiproc, int len_args, ...) {
     GLAD_UNUSED(len_args);
@@ -10077,10 +10085,12 @@ static int glad_gl_find_extensions_gl(void) {
     char **exts_i = NULL;
     if (!glad_gl_get_extensions(&exts, &exts_i)) return 0;
     GLAD_GL_ARB_copy_image = glad_gl_has_extension(exts, exts_i, "GL_ARB_copy_image");
+    GLAD_GL_ARB_framebuffer_sRGB = glad_gl_has_extension(exts, exts_i, "GL_ARB_framebuffer_sRGB");
     GLAD_GL_ARB_instanced_arrays = glad_gl_has_extension(exts, exts_i, "GL_ARB_instanced_arrays");
     GLAD_GL_ARB_multisample = glad_gl_has_extension(exts, exts_i, "GL_ARB_multisample");
     GLAD_GL_ARB_robustness = glad_gl_has_extension(exts, exts_i, "GL_ARB_robustness");
     GLAD_GL_ARB_texture_storage = glad_gl_has_extension(exts, exts_i, "GL_ARB_texture_storage");
+    GLAD_GL_EXT_framebuffer_sRGB = glad_gl_has_extension(exts, exts_i, "GL_EXT_framebuffer_sRGB");
     GLAD_GL_KHR_debug = glad_gl_has_extension(exts, exts_i, "GL_KHR_debug");
     glad_gl_free_extensions(exts_i);
     return 1;

kitty/gl.c

@@ -67,6 +67,13 @@ gl_init(void) {
         }
         ARB_TEST(texture_storage);
 #undef ARB_TEST
+#ifdef __APPLE__
+        // See nsgl_context.m srgb is always supported on macOS but its OpenGL
+        // drivers dont report the extensions, so hardcode to true.
+        global_state.supports_framebuffer_srgb = true;
+#else
+        global_state.supports_framebuffer_srgb = (GLAD_GL_ARB_framebuffer_sRGB + GLAD_GL_EXT_framebuffer_sRGB) != 0;
+#endif
         glad_loaded = true;
         int gl_major = GLAD_VERSION_MAJOR(global_state.gl_version);
         int gl_minor = GLAD_VERSION_MINOR(global_state.gl_version);

kitty/glfw.c

@@ -1381,6 +1381,7 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
         // Also apparently mesa has introduced a bug with sRGB surfaces and Wayland.
         // Sigh. Wayland is such a pile of steaming crap.
         // See https://github.com/kovidgoyal/kitty/issues/7174#issuecomment-2000033873
+        // GL_FRAMEBUFFER_SRGB works anyway without this on Wayland.
         if (!global_state.is_wayland) glfwWindowHint(GLFW_SRGB_CAPABLE, true);
 #ifdef __APPLE__
         cocoa_set_activation_policy(OPT(macos_hide_from_tasks) || lsc != NULL);
@@ -1459,7 +1460,6 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
 #undef glfw_failure
     glfwMakeContextCurrent(glfw_window);
     if (is_first_window) gl_init();
-    // Will make the GPU automatically apply SRGB gamma curve on the resulting framebuffer
     bool is_semi_transparent = glfwGetWindowAttrib(glfw_window, GLFW_TRANSPARENT_FRAMEBUFFER);
     // blank the window once so that there is no initial flash of color
     // changing, in case the background color is not black
@@ -1490,9 +1490,9 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
         if (ret == NULL) return NULL;
         Py_DECREF(ret);
         get_platform_dependent_config_values(glfw_window);
-        GLint encoding;
+        if (!global_state.supports_framebuffer_srgb) {
-        glGetFramebufferAttachmentParameteriv(GL_FRAMEBUFFER, GL_BACK_LEFT, GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING, &encoding);
+            log_error("The OpenGL drivers dont support GL_FRAMEBUFFER_SRGB this will cause a small rendering performance penalty");
-        if (encoding != GL_SRGB) log_error("The output buffer does not support sRGB color encoding, colors will be incorrect.");
+        }
         is_first_window = false;
     }
     OSWindow *w = add_os_window();

kitty/state.h

@@ -349,6 +349,7 @@ typedef struct {
     bool redirect_mouse_handling;
     WindowLogoTable *all_window_logos;
     int gl_version;
+    bool supports_framebuffer_srgb;
     PyObject *options_object;
 } GlobalState;