XCB: support creation of OpenGL ES profiles

The GLX_EXT_create_context_es2_profile extension allows us to create
OpenGL ES profiles even under a desktop OpenGL implementation.
Therefore, if a OpenGL ES renderable type is requested, and we have
that extension, we can fullfill the request.
We also strenghten the renderable types that the XCB plugin
supports (default, OpenGL, OpenGL ES).

Change-Id: I94ecbbaa910ab4c6d71185a69640e79594cb7bdc
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

1 files changed, 78 insertions, 46 deletions

diff --git a/src/plugins/platforms/xcb/qglxintegration.cpp b/src/plugins/platforms/xcb/qglxintegration.cpp
index 5efac6ce12..516b35dac8 100644
--- a/src/plugins/platforms/xcb/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/qglxintegration.cpp
@@ -71,6 +71,10 @@ typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXC
 #define GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB 0x00000002
 #endif
 
+#ifndef GLX_CONTEXT_ES2_PROFILE_BIT_EXT
+#define GLX_CONTEXT_ES2_PROFILE_BIT_EXT 0x00000004
+#endif
+
 #ifndef GLX_CONTEXT_PROFILE_MASK_ARB
 #define GLX_CONTEXT_PROFILE_MASK_ARB 0x9126
 #endif
@@ -123,33 +127,34 @@ static void updateFormatFromContext(QSurfaceFormat &format)
     }
 
     format.setProfile(QSurfaceFormat::NoProfile);
+    format.setOption(QSurfaceFormat::FormatOptions());
 
-    const int version = (major << 8) + minor;
-    if (version < 0x0300) {
-        format.setProfile(QSurfaceFormat::NoProfile);
-        format.setOption(QSurfaceFormat::DeprecatedFunctions);
-        return;
-    }
-
-    // Version 3.0 onwards - check if it includes deprecated functionality or is
-    // a debug context
-    GLint value = 0;
-    glGetIntegerv(GL_CONTEXT_FLAGS, &value);
-    if (!(value & GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT))
-        format.setOption(QSurfaceFormat::DeprecatedFunctions);
-    if (value & GL_CONTEXT_FLAG_DEBUG_BIT)
-        format.setOption(QSurfaceFormat::DebugContext);
-    if (version < 0x0302)
-        return;
-
-    // Version 3.2 and newer have a profile
-    value = 0;
-    glGetIntegerv(GL_CONTEXT_PROFILE_MASK, &value);
+    if (format.renderableType() == QSurfaceFormat::OpenGL) {
+        if (format.version() < qMakePair(3, 0)) {
+            format.setOption(QSurfaceFormat::DeprecatedFunctions);
+            return;
+        }
 
-    if (value & GL_CONTEXT_CORE_PROFILE_BIT)
-        format.setProfile(QSurfaceFormat::CoreProfile);
-    else if (value & GL_CONTEXT_COMPATIBILITY_PROFILE_BIT)
-        format.setProfile(QSurfaceFormat::CompatibilityProfile);
+        // Version 3.0 onwards - check if it includes deprecated functionality or is
+        // a debug context
+        GLint value = 0;
+        glGetIntegerv(GL_CONTEXT_FLAGS, &value);
+        if (!(value & GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT))
+            format.setOption(QSurfaceFormat::DeprecatedFunctions);
+        if (value & GL_CONTEXT_FLAG_DEBUG_BIT)
+            format.setOption(QSurfaceFormat::DebugContext);
+        if (format.version() < qMakePair(3, 2))
+            return;
+
+        // Version 3.2 and newer have a profile
+        value = 0;
+        glGetIntegerv(GL_CONTEXT_PROFILE_MASK, &value);
+
+        if (value & GL_CONTEXT_CORE_PROFILE_BIT)
+            format.setProfile(QSurfaceFormat::CoreProfile);
+        else if (value & GL_CONTEXT_COMPATIBILITY_PROFILE_BIT)
+            format.setProfile(QSurfaceFormat::CompatibilityProfile);
+    }
 }
 
 QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlatformOpenGLContext *share)
@@ -162,7 +167,7 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
 {
     if (m_format.renderableType() == QSurfaceFormat::DefaultRenderableType)
         m_format.setRenderableType(QSurfaceFormat::OpenGL);
-    if (m_format.renderableType() != QSurfaceFormat::OpenGL)
+    if (m_format.renderableType() != QSurfaceFormat::OpenGL && m_format.renderableType() != QSurfaceFormat::OpenGLES)
         return;
 
     if (share)
@@ -181,17 +186,31 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
         bool supportsProfiles = glxExt.contains("GLX_ARB_create_context_profile");
 
         // Use glXCreateContextAttribsARB if available
-        if (glxExt.contains("GLX_ARB_create_context") && glXCreateContextAttribsARB != 0) {
+        // Also, GL ES context creation requires GLX_EXT_create_context_es2_profile
+        if (glxExt.contains("GLX_ARB_create_context") && glXCreateContextAttribsARB != 0
+                && (m_format.renderableType() != QSurfaceFormat::OpenGLES || (supportsProfiles && glxExt.contains("GLX_EXT_create_context_es2_profile")))) {
             // Try to create an OpenGL context for each known OpenGL version in descending
             // order from the requested version.
             const int requestedVersion = format.majorVersion() * 10 + qMin(format.minorVersion(), 9);
 
             QVector<int> glVersions;
-            if (requestedVersion > 43)
-                glVersions << requestedVersion;
+            if (m_format.renderableType() == QSurfaceFormat::OpenGL) {
+                if (requestedVersion > 43)
+                    glVersions << requestedVersion;
+
+                // Don't bother with versions below 2.0
+                glVersions << 43 << 42 << 41 << 40 << 33 << 32 << 31 << 30 << 21 << 20;
+            } else if (m_format.renderableType() == QSurfaceFormat::OpenGLES) {
+                if (requestedVersion > 30)
+                    glVersions << requestedVersion;
+
+                // Don't bother with versions below ES 2.0
+                glVersions << 30 << 20;
+                // ES does not support any format option
+                m_format.setOption(QSurfaceFormat::FormatOptions());
+            }
 
-            // Don't bother with versions below 2.0
-            glVersions << 43 << 42 << 41 << 40 << 33 << 32 << 31 << 30 << 21 << 20;
+            Q_ASSERT(glVersions.count() > 0);
 
             for (int i = 0; !m_context && i < glVersions.count(); i++) {
                 const int version = glVersions[i];
@@ -205,25 +224,30 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
                 contextAttributes << GLX_CONTEXT_MAJOR_VERSION_ARB << majorVersion
                                   << GLX_CONTEXT_MINOR_VERSION_ARB << minorVersion;
 
-                // If asking for OpenGL 3.2 or newer we should also specify a profile
-                if (version >= 32 && supportsProfiles) {
-                    if (m_format.profile() == QSurfaceFormat::CoreProfile)
-                        contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
-                    else
-                        contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB;
-                }
 
-                int flags = 0;
+                if (m_format.renderableType() == QSurfaceFormat::OpenGL) {
+                    // If asking for OpenGL 3.2 or newer we should also specify a profile
+                    if (version >= 32 && supportsProfiles) {
+                        if (m_format.profile() == QSurfaceFormat::CoreProfile)
+                            contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
+                        else
+                            contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB;
+                    }
 
-                if (m_format.testOption(QSurfaceFormat::DebugContext))
-                    flags |= GLX_CONTEXT_DEBUG_BIT_ARB;
+                    int flags = 0;
 
-                // A forward-compatible context may be requested for 3.0 and later
-                if (version >= 30 && !m_format.testOption(QSurfaceFormat::DeprecatedFunctions))
-                    flags |= GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
+                    if (m_format.testOption(QSurfaceFormat::DebugContext))
+                        flags |= GLX_CONTEXT_DEBUG_BIT_ARB;
 
-                if (flags != 0)
-                    contextAttributes << GLX_CONTEXT_FLAGS_ARB << flags;
+                    // A forward-compatible context may be requested for 3.0 and later
+                    if (version >= 30 && !m_format.testOption(QSurfaceFormat::DeprecatedFunctions))
+                        flags |= GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
+
+                    if (flags != 0)
+                        contextAttributes << GLX_CONTEXT_FLAGS_ARB << flags;
+                } else if (m_format.renderableType() == QSurfaceFormat::OpenGLES) {
+                    contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_ES2_PROFILE_BIT_EXT;
+                }
 
                 contextAttributes << None;
 
@@ -239,6 +263,10 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
 
         // Could not create a context using glXCreateContextAttribsARB, falling back to glXCreateNewContext.
         if (!m_context) {
+            // requesting an OpenGL ES context requires glXCreateContextAttribsARB, so bail out
+            if (m_format.renderableType() == QSurfaceFormat::OpenGLES)
+                return;
+
             m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, m_shareContext, true);
             if (!m_context && m_shareContext) {
                 // re-try without a shared glx context
@@ -255,6 +283,10 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
         // Create a temporary window so that we can make the new context current
         window = createDummyWindow(screen, config);
     } else {
+        // requesting an OpenGL ES context requires glXCreateContextAttribsARB, so bail out
+        if (m_format.renderableType() == QSurfaceFormat::OpenGLES)
+            return;
+
         // Note that m_format gets updated with the used surface format
         visualInfo = qglx_findVisualInfo(DISPLAY_FROM_XCB(screen), screen->screenNumber(), &m_format);
         if (!visualInfo)