GHOST: Unify behavior of offscreen context creation

This makes sure the previously bound context is restored after creating a
new context. This follows what is already happening on windows.

All system backend are patched.

This also removes the goto and some code duplication.

Differential Revision: https://developer.blender.org/D12455

5 files changed, 93 insertions, 113 deletions

diff --git a/intern/ghost/intern/GHOST_SystemCocoa.mm b/intern/ghost/intern/GHOST_SystemCocoa.mm
index 189e663f91a..5a7d6ef2c01 100644
--- a/intern/ghost/intern/GHOST_SystemCocoa.mm
+++ b/intern/ghost/intern/GHOST_SystemCocoa.mm
@@ -767,13 +767,18 @@ GHOST_IWindow *GHOST_SystemCocoa::createWindow(const char *title,
  */
 GHOST_IContext *GHOST_SystemCocoa::createOffscreenContext(GHOST_GLSettings glSettings)
 {
+  NSOpenGLContext *prevContext = [NSOpenGLContext currentContext];
+
   GHOST_Context *context = new GHOST_ContextCGL(false, NULL, NULL, NULL);
-  if (context->initializeDrawingContext())
-    return context;
-  else
+  if (context->initializeDrawingContext() == false) {
     delete context;
-
-  return NULL;
+    context = nullptr;
+  }
+  /* Restore previously bound context. This is just to follow the win32 behavior. */
+  if (prevContext) {
+    [prevContext makeCurrentContext];
+  }
+  return context;
 }
 
 /**
diff --git a/intern/ghost/intern/GHOST_SystemSDL.cpp b/intern/ghost/intern/GHOST_SystemSDL.cpp
index 5370d4df857..77410407e21 100644
--- a/intern/ghost/intern/GHOST_SystemSDL.cpp
+++ b/intern/ghost/intern/GHOST_SystemSDL.cpp
@@ -141,6 +141,9 @@ uint8_t GHOST_SystemSDL::getNumDisplays() const
 
 GHOST_IContext *GHOST_SystemSDL::createOffscreenContext(GHOST_GLSettings glSettings)
 {
+  SDL_GLContext prev_context = SDL_GL_GetCurrentContext();
+  SDL_Window *prev_window = SDL_GL_GetCurrentWindow();
+
   GHOST_Context *context = new GHOST_ContextSDL(0,
                                                 NULL,
                                                 0, /* Profile bit. */
@@ -149,12 +152,18 @@ GHOST_IContext *GHOST_SystemSDL::createOffscreenContext(GHOST_GLSettings glSetti
                                                 GHOST_OPENGL_SDL_CONTEXT_FLAGS,
                                                 GHOST_OPENGL_SDL_RESET_NOTIFICATION_STRATEGY);
 
-  if (context->initializeDrawingContext())
-    return context;
-  else
+  if (context->initializeDrawingContext()) {
+    /* Pass */
+  }
+  else {
     delete context;
+    context = nullptr;
+  }
 
-  return NULL;
+  if (m_context) {
+    SDL_GL_MakeCurrent(prev_window, prev_context);
+  }
+  return context;
 }
 
 GHOST_TSuccess GHOST_SystemSDL::disposeContext(GHOST_IContext *context)
diff --git a/intern/ghost/intern/GHOST_SystemWayland.cpp b/intern/ghost/intern/GHOST_SystemWayland.cpp
index 38700845405..8cc84641d2e 100644
--- a/intern/ghost/intern/GHOST_SystemWayland.cpp
+++ b/intern/ghost/intern/GHOST_SystemWayland.cpp
@@ -1599,45 +1599,47 @@ GHOST_IContext *GHOST_SystemWayland::createOffscreenContext(GHOST_GLSettings /*g
 
   GHOST_Context *context;
 
-  for (int minor = 6; minor >= 0; --minor) {
+  EGLDisplay prev_display = eglGetCurrentDisplay();
+  /* It doesn't matter which one we query since we use the same surface for both read and write. */
+  EGLSurface prev_surface = eglGetCurrentSurface(EGL_DRAW);
+  EGLContext prev_context = eglGetCurrentContext();
+
+  const int versions[][2] = {{4, 6}, {4, 5}, {4, 4}, {4, 3}, {4, 2}, {4, 1}, {4, 0}, {3, 3}};
+  const int versions_len = sizeof(versions) / sizeof(versions[0]);
+
+  for (int i = 0; i < versions_len; i++) {
+    int major = versions[i][0];
+    int minor = versions[i][1];
+
     context = new GHOST_ContextEGL(this,
                                    false,
                                    EGLNativeWindowType(os_egl_window),
                                    EGLNativeDisplayType(d->display),
                                    EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT,
-                                   4,
+                                   major,
                                    minor,
                                    GHOST_OPENGL_EGL_CONTEXT_FLAGS,
                                    GHOST_OPENGL_EGL_RESET_NOTIFICATION_STRATEGY,
                                    EGL_OPENGL_API);
 
-    if (context->initializeDrawingContext())
-      return context;
-    else
+    if (context->initializeDrawingContext()) {
+      break;
+    }
+    else {
       delete context;
+      context = nullptr;
+    }
   }
 
-  context = new GHOST_ContextEGL(this,
-                                 false,
-                                 EGLNativeWindowType(os_egl_window),
-                                 EGLNativeDisplayType(d->display),
-                                 EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT,
-                                 3,
-                                 3,
-                                 GHOST_OPENGL_EGL_CONTEXT_FLAGS,
-                                 GHOST_OPENGL_EGL_RESET_NOTIFICATION_STRATEGY,
-                                 EGL_OPENGL_API);
-
-  if (context->initializeDrawingContext()) {
-    return context;
-  }
-  else {
-    delete context;
+  if (context == nullptr) {
+    GHOST_PRINT("Cannot create off-screen EGL context" << std::endl);
   }
 
-  GHOST_PRINT("Cannot create off-screen EGL context" << std::endl);
-
-  return nullptr;
+  if (prev_context) {
+    /* Restore previously bound context. This is just to follow the win32 behavior. */
+    eglMakeCurrent(prev_display, prev_surface, prev_surface, prev_context);
+  }
+  return context;
 }
 
 GHOST_TSuccess GHOST_SystemWayland::disposeContext(GHOST_IContext *context)
diff --git a/intern/ghost/intern/GHOST_SystemWin32.cpp b/intern/ghost/intern/GHOST_SystemWin32.cpp
index 482f20f5cd1..e0765ad85d5 100644
--- a/intern/ghost/intern/GHOST_SystemWin32.cpp
+++ b/intern/ghost/intern/GHOST_SystemWin32.cpp
@@ -284,69 +284,36 @@ GHOST_IContext *GHOST_SystemWin32::createOffscreenContext(GHOST_GLSettings glSet
   HDC mHDC = GetDC(wnd);
   HDC prev_hdc = wglGetCurrentDC();
   HGLRC prev_context = wglGetCurrentContext();
-#if defined(WITH_GL_PROFILE_CORE)
-  for (int minor = 5; minor >= 0; --minor) {
+
+  const int versions[][2] = {{4, 6}, {4, 5}, {4, 4}, {4, 3}, {4, 2}, {4, 1}, {4, 0}, {3, 3}};
+  const int versions_len = sizeof(versions) / sizeof(versions[0]);
+
+  for (int i = 0; i < versions_len; i++) {
+    int major = versions[i][0];
+    int minor = versions[i][1];
+
     context = new GHOST_ContextWGL(false,
                                    true,
                                    wnd,
                                    mHDC,
                                    WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
-                                   4,
+                                   major,
                                    minor,
                                    (debug_context ? WGL_CONTEXT_DEBUG_BIT_ARB : 0),
                                    GHOST_OPENGL_WGL_RESET_NOTIFICATION_STRATEGY);
 
     if (context->initializeDrawingContext()) {
-      goto finished;
+      break;
     }
     else {
       delete context;
+      context = nullptr;
     }
   }
 
-  context = new GHOST_ContextWGL(false,
-                                 true,
-                                 wnd,
-                                 mHDC,
-                                 WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
-                                 3,
-                                 3,
-                                 (debug_context ? WGL_CONTEXT_DEBUG_BIT_ARB : 0),
-                                 GHOST_OPENGL_WGL_RESET_NOTIFICATION_STRATEGY);
-
-  if (context->initializeDrawingContext()) {
-    goto finished;
-  }
-  else {
-    delete context;
-    return NULL;
+  if (prev_context) {
+    wglMakeCurrent(prev_hdc, prev_context);
   }
-
-#elif defined(WITH_GL_PROFILE_COMPAT)
-  // ask for 2.1 context, driver gives any GL version >= 2.1
-  // (hopefully the latest compatibility profile)
-  // 2.1 ignores the profile bit & is incompatible with core profile
-  context = new GHOST_ContextWGL(false,
-                                 true,
-                                 NULL,
-                                 NULL,
-                                 0,  // no profile bit
-                                 2,
-                                 1,
-                                 (debug_context ? WGL_CONTEXT_DEBUG_BIT_ARB : 0),
-                                 GHOST_OPENGL_WGL_RESET_NOTIFICATION_STRATEGY);
-
-  if (context->initializeDrawingContext()) {
-    return context;
-  }
-  else {
-    delete context;
-  }
-#else
-#  error  // must specify either core or compat at build time
-#endif
-finished:
-  wglMakeCurrent(prev_hdc, prev_context);
   return context;
 }
 
diff --git a/intern/ghost/intern/GHOST_SystemX11.cpp b/intern/ghost/intern/GHOST_SystemX11.cpp
index ab8039ea95d..98f5f41d5e8 100644
--- a/intern/ghost/intern/GHOST_SystemX11.cpp
+++ b/intern/ghost/intern/GHOST_SystemX11.cpp
@@ -437,16 +437,32 @@ GHOST_IContext *GHOST_SystemX11::createOffscreenContext(GHOST_GLSettings glSetti
 #  endif
 #endif
 
+#if defined(WITH_GL_EGL)
+  EGLDisplay prev_display = eglGetCurrentDisplay();
+  /* It doesn't matter which one we query since we use the same surface for both read and write. */
+  EGLSurface prev_surface = eglGetCurrentSurface(EGL_DRAW);
+  EGLContext prev_context = eglGetCurrentContext();
+#else
+  Display *prev_display = glXGetCurrentDisplay();
+  GLXDrawable prev_drawable = glXGetCurrentDrawable();
+  GLXContext prev_context = glXGetCurrentContext();
+#endif
+
   GHOST_Context *context;
 
-  for (int minor = 5; minor >= 0; --minor) {
+  const int versions[][2] = {{4, 6}, {4, 5}, {4, 4}, {4, 3}, {4, 2}, {4, 1}, {4, 0}, {3, 3}};
+  const int versions_len = sizeof(versions) / sizeof(versions[0]);
+
+  for (int i = 0; i < versions_len; i++) {
+    int major = versions[i][0];
+    int minor = versions[i][1];
 #if defined(WITH_GL_EGL)
     context = new GHOST_ContextEGL(this,
                                    false,
                                    EGLNativeWindowType(nullptr),
                                    EGLNativeDisplayType(m_display),
                                    profile_mask,
-                                   4,
+                                   major,
                                    minor,
                                    GHOST_OPENGL_EGL_CONTEXT_FLAGS |
                                        (debug_context ? EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR : 0),
@@ -458,50 +474,31 @@ GHOST_IContext *GHOST_SystemX11::createOffscreenContext(GHOST_GLSettings glSetti
                                    m_display,
                                    (GLXFBConfig)NULL,
                                    profile_mask,
-                                   4,
+                                   major,
                                    minor,
                                    GHOST_OPENGL_GLX_CONTEXT_FLAGS |
                                        (debug_context ? GLX_CONTEXT_DEBUG_BIT_ARB : 0),
                                    GHOST_OPENGL_GLX_RESET_NOTIFICATION_STRATEGY);
 #endif
 
-    if (context->initializeDrawingContext())
-      return context;
-    else
+    if (context->initializeDrawingContext()) {
+      break;
+    }
+    else {
       delete context;
+      context = nullptr;
+    }
   }
 
+  if (prev_context) {
+    /* Restore previously bound context. This is just to follow the win32 behavior. */
 #if defined(WITH_GL_EGL)
-  context = new GHOST_ContextEGL(this,
-                                 false,
-                                 EGLNativeWindowType(nullptr),
-                                 EGLNativeDisplayType(m_display),
-                                 profile_mask,
-                                 3,
-                                 3,
-                                 GHOST_OPENGL_EGL_CONTEXT_FLAGS |
-                                     (debug_context ? EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR : 0),
-                                 GHOST_OPENGL_EGL_RESET_NOTIFICATION_STRATEGY,
-                                 EGL_OPENGL_API);
+    eglMakeCurrent(prev_display, prev_surface, prev_surface, prev_context);
 #else
-  context = new GHOST_ContextGLX(false,
-                                 (Window)NULL,
-                                 m_display,
-                                 (GLXFBConfig)NULL,
-                                 profile_mask,
-                                 3,
-                                 3,
-                                 GHOST_OPENGL_GLX_CONTEXT_FLAGS |
-                                     (debug_context ? GLX_CONTEXT_DEBUG_BIT_ARB : 0),
-                                 GHOST_OPENGL_GLX_RESET_NOTIFICATION_STRATEGY);
+    glXMakeCurrent(prev_display, prev_drawable, prev_context);
 #endif
-
-  if (context->initializeDrawingContext())
-    return context;
-  else
-    delete context;
-
-  return NULL;
+  }
+  return context;
 }
 
 /**