winex11.drv: Fix wglSwapBuffers() with NULL current context with child window rendering.

dlls/opengl32/tests/opengl.c

@@ -2006,6 +2006,55 @@ static void test_copy_context(HDC hdc)
     ok(ret, "wglMakeCurrent failed, last error %#lx.\n", GetLastError());
 }
 
+static void test_child_window(HWND hwnd, PIXELFORMATDESCRIPTOR *pfd)
+{
+    int pixel_format;
+    DWORD t1, t;
+    HGLRC hglrc;
+    HWND child;
+    HDC hdc;
+    int res;
+
+    child = CreateWindowA("static", "Title", WS_CHILDWINDOW | WS_VISIBLE, 50, 50, 100, 100, hwnd, NULL, NULL, NULL);
+    ok(!!child, "got error %lu.\n", GetLastError());
+
+    hdc = GetDC(child);
+    pixel_format = ChoosePixelFormat(hdc, pfd);
+    res = SetPixelFormat(hdc, pixel_format, pfd);
+    ok(res, "got error %lu.\n", GetLastError());
+
+    hglrc = wglCreateContext(hdc);
+    ok(!!hglrc, "got error %lu.\n", GetLastError());
+
+    /* Test SwapBuffers with NULL context. */
+
+    glDrawBuffer(GL_BACK);
+
+    /* Currently blit happening for child window in winex11 may not be updated with the latest GL frame
+     * even on glXWaitForSbcOML() path. So simulate continuous present for the test purpose. */
+    trace("Child window rectangle should turn from red to green now.\n");
+    t1 = GetTickCount();
+    while ((t = GetTickCount()) - t1 < 3000)
+    {
+        res = wglMakeCurrent(hdc, hglrc);
+        ok(res, "got error %lu.\n", GetLastError());
+        if (t - t1 > 1500)
+            glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
+        else
+            glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT);
+        res = wglMakeCurrent(NULL, NULL);
+        ok(res, "got error %lu.\n", GetLastError());
+        SwapBuffers(hdc);
+    }
+
+    res = wglDeleteContext(hglrc);
+    ok(res, "got error %lu.\n", GetLastError());
+
+    ReleaseDC(child, hdc);
+    DestroyWindow(child);
+}
+
 START_TEST(opengl)
 {
     HWND hwnd;
@@ -2138,6 +2187,9 @@ START_TEST(opengl)
         else
             skip("WGL_EXT_swap_control not supported, skipping test\n");
 
+        if (winetest_interactive)
+            test_child_window(hwnd, &pfd);
+
 cleanup:
         ReleaseDC(hwnd, hdc);
         DestroyWindow(hwnd);

dlls/winex11.drv/opengl.c

@@ -3378,7 +3378,7 @@ static BOOL glxdrv_wglSwapBuffers( HDC hdc )
     case DC_GL_PIXMAP_WIN:
         if (ctx) sync_context( ctx );
         escape.gl_drawable = gl->pixmap;
-        if (pglXCopySubBufferMESA) {
+        if (ctx && pglXCopySubBufferMESA) {
             /* (glX)SwapBuffers has an implicit glFlush effect, however
              * GLX_MESA_copy_sub_buffer doesn't. Make sure GL is flushed before
              * copying */
@@ -3387,7 +3387,7 @@ static BOOL glxdrv_wglSwapBuffers( HDC hdc )
                                    gl->pixmap_size.cx, gl->pixmap_size.cy );
             break;
         }
-        if (pglXSwapBuffersMscOML)
+        if (ctx && pglXSwapBuffersMscOML)
         {
             pglFlush();
             target_sbc = pglXSwapBuffersMscOML( gdi_display, gl->drawable, 0, 0, 0 );
@@ -3401,7 +3401,7 @@ static BOOL glxdrv_wglSwapBuffers( HDC hdc )
         if (gl->type == DC_GL_CHILD_WIN) escape.gl_drawable = gl->window;
         /* fall through */
     default:
-        if (escape.gl_drawable && pglXSwapBuffersMscOML)
+        if (ctx && escape.gl_drawable && pglXSwapBuffersMscOML)
         {
             pglFlush();
             target_sbc = pglXSwapBuffersMscOML( gdi_display, gl->drawable, 0, 0, 0 );
@@ -3411,13 +3411,13 @@ static BOOL glxdrv_wglSwapBuffers( HDC hdc )
         break;
     }
 
-    if (escape.gl_drawable && pglXWaitForSbcOML)
+    if (ctx && escape.gl_drawable && pglXWaitForSbcOML)
         pglXWaitForSbcOML( gdi_display, gl->drawable, target_sbc, &ust, &msc, &sbc );
 
     release_gl_drawable( gl );
 
     if (escape.gl_drawable)
-        NtGdiExtEscape( ctx->hdc, NULL, 0, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
+        NtGdiExtEscape( ctx ? ctx->hdc : hdc, NULL, 0, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
     return TRUE;
 }