Merge branch 'master' into drag-window-dev

CONTRIBUTORS.md

@@ -185,6 +185,7 @@ video tutorials.
  - pthom
  - Martin Pulec
  - Guillaume Racicot
+ - Christian Rauch
  - Philip Rideout
  - Eddie Ringle
  - Max Risuhin

README.md

@@ -316,6 +316,8 @@ information on what to include when reporting a bug.
  - [Wayland] Added support for key names via xkbcommon
  - [Wayland] Added support for file path drop events (#2040)
  - [Wayland] Added support for more human-readable monitor names where available
+ - [Wayland] Disabled alpha channel for opaque windows on systems lacking
+   `EGL_EXT_present_opaque` (#1895)
  - [Wayland] Removed support for `wl_shell` (#1443)
  - [Wayland] Bugfix: The `GLFW_HAND_CURSOR` shape used the wrong image (#1432)
  - [Wayland] Bugfix: `CLOCK_MONOTONIC` was not correctly enabled

docs/news.dox

@@ -126,6 +126,19 @@ To work around this, call any joystick function before waiting for events, for
 example by setting a [joystick callback](@ref joystick_event).
 
 
+@subsubsection wayland_alpha_34 Frambuffer may lack alpha channel on older Wayland systems
+
+On Wayland, when creating an EGL context on a machine lacking the new
+`EGL_EXT_present_opaque` extension, the @ref GLFW_ALPHA_BITS window hint will be
+ignored and the framebuffer will have no alpha channel.  This is because some
+Wayland compositors treat any buffer with an alpha channel as per-pixel
+transparent.
+
+If you want a per-pixel transparent window, see the
+[GLFW_TRANSPARENT_FRAMEBUFFER](@ref GLFW_TRANSPARENT_FRAMEBUFFER_hint) window
+hint.
+
+
 @subsubsection standalone_34 Tests and examples are disabled when built as a subproject
 
 GLFW now does not build the tests and examples when it is added as

src/context.c

@@ -48,16 +48,6 @@
 //
 GLFWbool _glfwIsValidContextConfig(const _GLFWctxconfig* ctxconfig)
 {
-    if (ctxconfig->share)
-    {
-        if (ctxconfig->client == GLFW_NO_API ||
-            ctxconfig->share->context.client == GLFW_NO_API)
-        {
-            _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
-            return GLFW_FALSE;
-        }
-    }
-
     if (ctxconfig->source != GLFW_NATIVE_CONTEXT_API &&
         ctxconfig->source != GLFW_EGL_CONTEXT_API &&
         ctxconfig->source != GLFW_OSMESA_CONTEXT_API)
@@ -78,6 +68,23 @@ GLFWbool _glfwIsValidContextConfig(const _GLFWctxconfig* ctxconfig)
         return GLFW_FALSE;
     }
 
+    if (ctxconfig->share)
+    {
+        if (ctxconfig->client == GLFW_NO_API ||
+            ctxconfig->share->context.client == GLFW_NO_API)
+        {
+            _glfwInputError(GLFW_NO_WINDOW_CONTEXT, NULL);
+            return GLFW_FALSE;
+        }
+
+        if (ctxconfig->source != ctxconfig->share->context.source)
+        {
+            _glfwInputError(GLFW_INVALID_ENUM,
+                            "Context creation APIs do not match between contexts");
+            return GLFW_FALSE;
+        }
+    }
+
     if (ctxconfig->client == GLFW_OPENGL_API)
     {
         if ((ctxconfig->major < 1 || ctxconfig->minor < 0) ||

src/egl_context.c

@@ -173,6 +173,21 @@ static GLFWbool chooseEGLConfig(const _GLFWctxconfig* ctxconfig,
         u->depthBits = getEGLConfigAttrib(n, EGL_DEPTH_SIZE);
         u->stencilBits = getEGLConfigAttrib(n, EGL_STENCIL_SIZE);
 
+#if defined(_GLFW_WAYLAND)
+        if (_glfw.platform.platformID == GLFW_PLATFORM_WAYLAND)
+        {
+            // NOTE: The wl_surface opaque region is no guarantee that its buffer
+            //       is presented as opaque, if it also has an alpha channel
+            // HACK: If EGL_EXT_present_opaque is unavailable, ignore any config
+            //       with an alpha channel to ensure the buffer is opaque
+            if (!_glfw.egl.EXT_present_opaque)
+            {
+                if (!desired->transparent && u->alphaBits > 0)
+                    continue;
+            }
+        }
+#endif // _GLFW_WAYLAND
+
         u->samples = getEGLConfigAttrib(n, EGL_SAMPLES);
         u->doublebuffer = desired->doublebuffer;
 

src/wgl_context.c

@@ -72,18 +72,13 @@ static int choosePixelFormatWGL(_GLFWwindow* window,
     int attribs[40];
     int values[sizeof(attribs) / sizeof(attribs[0])];
 
+    nativeCount = DescribePixelFormat(window->context.wgl.dc,
+                                      1,
+                                      sizeof(PIXELFORMATDESCRIPTOR),
+                                      NULL);
+
     if (_glfw.wgl.ARB_pixel_format)
     {
-        const int attrib = WGL_NUMBER_PIXEL_FORMATS_ARB;
-
-        if (!wglGetPixelFormatAttribivARB(window->context.wgl.dc,
-                                          1, 0, 1, &attrib, &nativeCount))
-        {
-            _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
-                                 "WGL: Failed to retrieve pixel format attribute");
-            return 0;
-        }
-
         ADD_ATTRIB(WGL_SUPPORT_OPENGL_ARB);
         ADD_ATTRIB(WGL_DRAW_TO_WINDOW_ARB);
         ADD_ATTRIB(WGL_PIXEL_TYPE_ARB);
@@ -121,13 +116,6 @@ static int choosePixelFormatWGL(_GLFWwindow* window,
                 ADD_ATTRIB(WGL_COLORSPACE_EXT);
         }
     }
-    else
-    {
-        nativeCount = DescribePixelFormat(window->context.wgl.dc,
-                                          1,
-                                          sizeof(PIXELFORMATDESCRIPTOR),
-                                          NULL);
-    }
 
     usableConfigs = _glfw_calloc(nativeCount, sizeof(_GLFWfbconfig));