Fixes: Add blitting and multisample API to QGLFramebufferObject.

RevBy:    Trond
Details:  Support GL_EXT_framebuffer_multisample and GL_EXT_framebuffer_blit
          in the QGLFramebufferObject API.

6 files changed, 520 insertions, 30 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 558897d..fc11d90 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -4175,6 +4175,8 @@ void QGLExtensions::init_extensions()
     glExtensions |= FramebufferObject;
     glExtensions |= GenerateMipmap;
 #endif
+    if (extensions.contains(QLatin1String("EXT_framebuffer_blit")))
+        glExtensions |= FramebufferBlit;
 
     QGLContext cx(QGLFormat::defaultFormat());
     if (glExtensions & TextureCompression) {
diff --git a/src/opengl/qgl_p.h b/src/opengl/qgl_p.h
index 76f3812..8ab73d8 100644
--- a/src/opengl/qgl_p.h
+++ b/src/opengl/qgl_p.h
@@ -330,7 +330,8 @@ public:
         StencilWrap             = 0x00000100,
         PackedDepthStencil      = 0x00000200,
         NVFloatBuffer           = 0x00000400,
-        PixelBufferObject       = 0x00000800
+        PixelBufferObject       = 0x00000800,
+        FramebufferBlit         = 0x00001000
     };
     Q_DECLARE_FLAGS(Extensions, Extension)
 
diff --git a/src/opengl/qglextensions.cpp b/src/opengl/qglextensions.cpp
index b054fe8..e6ac043 100644
--- a/src/opengl/qglextensions.cpp
+++ b/src/opengl/qglextensions.cpp
@@ -74,6 +74,9 @@ bool qt_resolve_framebufferobject_extensions(QGLContext *ctx)
     glGetFramebufferAttachmentParameterivEXT =
         (_glGetFramebufferAttachmentParameterivEXT) ctx->getProcAddress(QLatin1String("glGetFramebufferAttachmentParameterivEXT"));
     glGenerateMipmapEXT = (_glGenerateMipmapEXT) ctx->getProcAddress(QLatin1String("glGenerateMipmapEXT"));
+    glBlitFramebufferEXT = (_glBlitFramebufferEXT) ctx->getProcAddress(QLatin1String("glBlitFramebufferEXT"));
+    glRenderbufferStorageMultisampleEXT =
+        (_glRenderbufferStorageMultisampleEXT) ctx->getProcAddress(QLatin1String("glRenderbufferStorageMultisampleEXT"));
     return glIsRenderbufferEXT;
 #else
     Q_UNUSED(ctx);
diff --git a/src/opengl/qglextensions_p.h b/src/opengl/qglextensions_p.h
index fdf0bba..cd35eb0 100644
--- a/src/opengl/qglextensions_p.h
+++ b/src/opengl/qglextensions_p.h
@@ -162,6 +162,15 @@ typedef void (APIENTRY *_glGetFramebufferAttachmentParameterivEXT) (GLenum targe
                                                                           GLint *params);
 typedef void (APIENTRY *_glGenerateMipmapEXT) (GLenum target);
 
+// EXT_GL_framebuffer_blit
+typedef void (APIENTRY *_glBlitFramebufferEXT) (int srcX0, int srcY0, int srcX1, int srcY1,
+                                                int dstX0, int dstY0, int dstX1, int dstY1,
+                                                GLbitfield mask, GLenum filter);
+
+// EXT_GL_framebuffer_multisample
+typedef void (APIENTRY *_glRenderbufferStorageMultisampleEXT) (GLenum target, GLsizei samples,
+                                                               GLenum internalformat, GLsizei width, GLsizei height);
+
 QT_BEGIN_NAMESPACE
 
 struct QGLExtensionFuncs
@@ -220,6 +229,8 @@ struct QGLExtensionFuncs
         qt_glGetFramebufferAttachmentParameterivEXT = 0;
         qt_glGenerateMipmapEXT = 0;
 #endif
+        qt_glBlitFramebufferEXT = 0;
+        qt_glRenderbufferStorageMultisampleEXT = 0;
 
         qt_glBindBufferARB = 0;
         qt_glDeleteBuffersARB = 0;
@@ -298,6 +309,8 @@ struct QGLExtensionFuncs
     _glGetFramebufferAttachmentParameterivEXT qt_glGetFramebufferAttachmentParameterivEXT;
     _glGenerateMipmapEXT qt_glGenerateMipmapEXT;
 #endif
+    _glBlitFramebufferEXT qt_glBlitFramebufferEXT;
+    _glRenderbufferStorageMultisampleEXT qt_glRenderbufferStorageMultisampleEXT;
 
     _glBindBufferARB qt_glBindBufferARB;
     _glDeleteBuffersARB qt_glDeleteBuffersARB;
@@ -447,6 +460,28 @@ struct QGLExtensionFuncs
 #define GL_RENDERBUFFER_STENCIL_SIZE_EXT                        0x8D55
 #endif
 
+// GL_EXT_framebuffer_blit
+#ifndef GL_READ_FRAMEBUFFER_EXT
+#define GL_READ_FRAMEBUFFER_EXT                                 0x8CA8
+#endif
+
+// GL_EXT_framebuffer_multisample
+#ifndef GL_RENDERBUFFER_SAMPLES_EXT
+#define GL_RENDERBUFFER_SAMPLES_EXT                             0x8CAB
+#endif
+
+#ifndef GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT
+#define GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT               0x8D56
+#endif
+
+#ifndef GL_MAX_SAMPLES_EXT
+#define GL_MAX_SAMPLES_EXT                                      0x8D5
+#endif
+
+#ifndef GL_DRAW_FRAMEBUFFER_EXT
+#define GL_DRAW_FRAMEBUFFER_EXT                                 0x8CA9
+#endif
+
 #ifndef GL_EXT_packed_depth_stencil
 #define GL_DEPTH_STENCIL_EXT                                    0x84F9
 #define GL_UNSIGNED_INT_24_8_EXT                                0x84FA
@@ -533,6 +568,8 @@ struct QGLExtensionFuncs
 #define glFramebufferRenderbufferEXT QGLContextPrivate::qt_get_extension_funcs(ctx).qt_glFramebufferRenderbufferEXT
 #define glGetFramebufferAttachmentParameterivEXT QGLContextPrivate::qt_get_extension_funcs(ctx).qt_glGetFramebufferAttachmentParameterivEXT
 #define glGenerateMipmapEXT QGLContextPrivate::qt_get_extension_funcs(ctx).qt_glGenerateMipmapEXT
+#define glBlitFramebufferEXT QGLContextPrivate::qt_get_extension_funcs(ctx).qt_glBlitFramebufferEXT
+#define glRenderbufferStorageMultisampleEXT QGLContextPrivate::qt_get_extension_funcs(ctx).qt_glRenderbufferStorageMultisampleEXT
 
 #else // QT_OPENGL_ES_2
 
diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index 9134fc6..297ef84 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -67,6 +67,216 @@ extern QImage qt_gl_read_framebuffer(const QSize&, bool, bool);
     }                                                     \
 }
 
+class QGLFramebufferObjectFormatPrivate
+{
+public:
+    int samples;
+    QGLFramebufferObject::Attachment attachment;
+    GLenum target;
+    GLenum internal_format;
+};
+
+/*!
+    \class QGLFramebufferObjectFormat
+    \brief The QGLFramebufferObjectFormat class specifies the format of an OpenGL
+    framebuffer object.
+
+    \since 4.6
+
+    \ingroup multimedia
+
+    A framebuffer object has several characteristics:
+    \list
+    \i \link setSamples() Number of samples per pixels.\endlink
+    \i \link setAttachment() Depth and/or stencil attachments.\endlink
+    \i \link setTextureTarget() Texture target.\endlink
+    \i \link setInternalFormat() Internal format.\endlink
+    \endlist
+
+    Note that the desired attachments or number of samples per pixels might not
+    be supported by the hardware driver. Call QGLFramebufferObject::format()
+    after creating a QGLFramebufferObject to find the exact format that was
+    used to create the frame buffer object.
+
+    \sa QGLFramebufferObject
+*/
+
+/*!
+    \since 4.6
+
+    Creates a QGLFramebufferObjectFormat object with properties specifying
+    the format of an OpenGL framebuffer object.
+
+    A multisample framebuffer object is specified by setting \a samples
+    to a value different from zero. If the desired amount of samples per pixel is
+    not supported by the hardware then the maximum number of samples per pixel
+    will be used. Note that multisample framebuffer objects can not be bound as
+    textures. Also, the \c{GL_EXT_framebuffer_multisample} extension is required
+    to create a framebuffer with more than one sample per pixel.
+
+    For multisample framebuffer objects a color render buffer is created,
+    otherwise a texture with the texture target \a target is created.
+    The color render buffer or texture will have the internal format
+    \a internalFormat, and will be bound to the \c GL_COLOR_ATTACHMENT0
+    attachment in the framebuffer object.
+
+    The \a attachment parameter describes the depth/stencil buffer
+    configuration.
+
+    \sa samples(), attachment(), target(), internalFormat()
+*/
+
+QGLFramebufferObjectFormat::QGLFramebufferObjectFormat(int samples,
+                                                       QGLFramebufferObject::Attachment attachment,
+                                                       GLenum target,
+                                                       GLenum internalFormat)
+{
+    d = new QGLFramebufferObjectFormatPrivate;
+    d->samples = samples;
+    d->attachment = attachment;
+    d->target = target;
+    d->internal_format = internalFormat;
+}
+
+/*!
+    \since 4.6
+
+    Constructs a copy of \a other.
+*/
+
+QGLFramebufferObjectFormat::QGLFramebufferObjectFormat(const QGLFramebufferObjectFormat &other)
+{
+    d = new QGLFramebufferObjectFormatPrivate;
+    *d = *other.d;
+}
+
+/*!
+    \since 4.6
+
+    Assigns \a other to this object.
+*/
+
+QGLFramebufferObjectFormat::QGLFramebufferObjectFormat &
+QGLFramebufferObjectFormat::operator=(const QGLFramebufferObjectFormat &other)
+{
+    *d = *other.d;
+    return *this;
+}
+
+/*!
+    \since 4.6
+
+    Destroys the QGLFramebufferObjectFormat.
+*/
+QGLFramebufferObjectFormat::~QGLFramebufferObjectFormat()
+{
+    delete d;
+}
+
+/*!
+    \since 4.6
+
+    Sets the number of samples per pixel for a multisample framebuffer object
+    to \a samples.
+    A sample count of 0 represents a regular non-multisample framebuffer object.
+
+    \sa samples()
+*/
+void QGLFramebufferObjectFormat::setSamples(int samples)
+{
+    d->samples = samples;
+}
+
+/*!
+    \since 4.6
+
+    Returns the number of samples per pixel if a framebuffer object
+    is a multisample framebuffer object. Otherwise, returns 0.
+
+    \sa setSamples()
+*/
+int QGLFramebufferObjectFormat::samples() const
+{
+    return d->samples;
+}
+
+/*!
+    \since 4.6
+
+    Sets the attachments a framebuffer object should have to \a attachment.
+
+    \sa attachment()
+*/
+void QGLFramebufferObjectFormat::setAttachment(QGLFramebufferObject::Attachment attachment)
+{
+    d->attachment = attachment;
+}
+
+/*!
+    \since 4.6
+
+    Returns the status of the depth and stencil buffers attached to
+    a framebuffer object.
+
+    \sa setAttachment()
+*/
+QGLFramebufferObject::Attachment QGLFramebufferObjectFormat::attachment() const
+{
+    return d->attachment;
+}
+
+/*!
+    \since 4.6
+
+    Sets the texture target of the texture attached to a framebuffer object to
+    \a target. Ignored for multisample framebuffer objects.
+
+    \sa textureTarget(), samples()
+*/
+void QGLFramebufferObjectFormat::setTextureTarget(GLenum target)
+{
+    d->target = target;
+}
+
+/*!
+    \since 4.6
+
+    Returns the texture target of the texture attached to a framebuffer object.
+    Ignored for multisample framebuffer objects.
+
+    \sa setTextureTarget(), samples()
+*/
+GLenum QGLFramebufferObjectFormat::textureTarget() const
+{
+    return d->target;
+}
+
+/*!
+    \since 4.6
+
+    Sets the internal format of a framebuffer object's texture or multisample
+    framebuffer object's color buffer to \a internalFormat.
+
+    \sa internalFormat()
+*/
+void QGLFramebufferObjectFormat::setInternalFormat(GLenum internalFormat)
+{
+    d->internal_format = internalFormat;
+}
+
+/*!
+    \since 4.6
+
+    Returns the internal format of a framebuffer object's texture or
+    multisample framebuffer object's color buffer.
+
+    \sa setInternalFormat()
+*/
+GLenum QGLFramebufferObjectFormat::internalFormat() const
+{
+    return d->internal_format;
+}
+
 class QGLFramebufferObjectPrivate
 {
 public:
@@ -74,13 +284,16 @@ public:
     ~QGLFramebufferObjectPrivate() {}
 
     void init(const QSize& sz, QGLFramebufferObject::Attachment attachment,
-              GLenum internal_format, GLenum texture_target);
+              GLenum internal_format, GLenum texture_target, int samples = 0);
     bool checkFramebufferStatus() const;
     GLuint texture;
     GLuint fbo;
     GLuint depth_stencil_buffer;
+    GLuint color_buffer;
     GLenum target;
     QSize size;
+    QGLFramebufferObjectFormat format;
+    int samples;
     uint valid : 1;
     uint bound : 1;
     QGLFramebufferObject::Attachment fbo_attachment;
@@ -122,6 +335,9 @@ bool QGLFramebufferObjectPrivate::checkFramebufferStatus() const
     case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT:
         qDebug("QGLFramebufferObject: Framebuffer incomplete, missing read buffer.");
         break;
+    case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT:
+        qDebug("QGLFramebufferObject: Framebuffer incomplete, attachments must have same number of samples per pixel.");
+        break;
     default:
         qDebug() <<"QGLFramebufferObject: An undefined error has occurred: "<< status;
         break;
@@ -130,7 +346,7 @@ bool QGLFramebufferObjectPrivate::checkFramebufferStatus() const
 }
 
 void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::Attachment attachment,
-                                       GLenum texture_target, GLenum internal_format)
+                                       GLenum texture_target, GLenum internal_format, int samples)
 {
     ctx = const_cast<QGLContext *>(QGLContext::currentContext());
     bool ext_detected = (QGLExtensions::glExtensions & QGLExtensions::FramebufferObject);
@@ -147,26 +363,56 @@ void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::At
 
     QT_CHECK_GLERROR();
     // init texture
-    glGenTextures(1, &texture);
-    glBindTexture(target, texture);
-    glTexImage2D(target, 0, internal_format, size.width(), size.height(), 0,
-                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+    if (samples == 0) {
+        glGenTextures(1, &texture);
+        glBindTexture(target, texture);
+        glTexImage2D(target, 0, internal_format, size.width(), size.height(), 0,
+                GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 #ifndef QT_OPENGL_ES
-    glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-    glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-    glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-    glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glTexParameteri(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 #else
-    glTexParameterf(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-    glTexParameterf(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-    glTexParameterf(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-    glTexParameterf(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameterf(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameterf(target, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glTexParameterf(target, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameterf(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 #endif
-    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
-                              target, texture, 0);
+        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
+                target, texture, 0);
 
-    QT_CHECK_GLERROR();
-    valid = checkFramebufferStatus();
+        QT_CHECK_GLERROR();
+        valid = checkFramebufferStatus();
+
+        color_buffer = 0;
+        samples = 0;
+    } else {
+        GLint maxSamples;
+        glGetIntegerv(GL_MAX_SAMPLES_EXT, &maxSamples);
+
+        samples = qBound(1, samples, int(maxSamples));
+
+        glGenRenderbuffersEXT(1, &color_buffer);
+        glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, color_buffer);
+        if (glRenderbufferStorageMultisampleEXT) {
+            glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
+                internal_format, size.width(), size.height());
+        } else {
+            samples = 0;
+            glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, internal_format,
+                size.width(), size.height());
+        }
+
+        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
+                                     GL_RENDERBUFFER_EXT, color_buffer);
+
+        QT_CHECK_GLERROR();
+        valid = checkFramebufferStatus();
+
+        if (valid)
+            glGetRenderbufferParameterivEXT(GL_RENDERBUFFER_EXT, GL_RENDERBUFFER_SAMPLES_EXT, &samples);
+    }
 
     if (attachment == QGLFramebufferObject::CombinedDepthStencil
         && (QGLExtensions::glExtensions & QGLExtensions::PackedDepthStencil)) {
@@ -175,7 +421,13 @@ void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::At
         Q_ASSERT(!glIsRenderbufferEXT(depth_stencil_buffer));
         glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depth_stencil_buffer);
         Q_ASSERT(glIsRenderbufferEXT(depth_stencil_buffer));
-        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT, size.width(), size.height());
+        if (samples != 0 && glRenderbufferStorageMultisampleEXT)
+            glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
+                GL_DEPTH24_STENCIL8_EXT, size.width(), size.height());
+        else
+            glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT,
+                GL_DEPTH24_STENCIL8_EXT, size.width(), size.height());
+
         GLint i = 0;
         glGetRenderbufferParameterivEXT(GL_RENDERBUFFER_EXT, GL_RENDERBUFFER_DEPTH_SIZE_EXT, &i);
         glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
@@ -183,6 +435,7 @@ void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::At
         glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
                                      GL_RENDERBUFFER_EXT, depth_stencil_buffer);
         fbo_attachment = QGLFramebufferObject::CombinedDepthStencil;
+
         valid = checkFramebufferStatus();
         if (!valid)
             glDeleteRenderbuffersEXT(1, &depth_stencil_buffer);
@@ -193,12 +446,23 @@ void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::At
         Q_ASSERT(!glIsRenderbufferEXT(depth_stencil_buffer));
         glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, depth_stencil_buffer);
         Q_ASSERT(glIsRenderbufferEXT(depth_stencil_buffer));
+        if (samples != 0 && glRenderbufferStorageMultisampleEXT) {
 #ifdef QT_OPENGL_ES
 #define GL_DEPTH_COMPONENT16 0x81A5
-        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT16, size.width(), size.height());
+            glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
+                GL_DEPTH_COMPONENT16, size.width(), size.height());
 #else
-        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, size.width(), size.height());
+            glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
+                GL_DEPTH_COMPONENT, size.width(), size.height());
 #endif
+        } else {
+#ifdef QT_OPENGL_ES
+#define GL_DEPTH_COMPONENT16 0x81A5
+            glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT16, size.width(), size.height());
+#else
+            glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, size.width(), size.height());
+#endif
+        }
         GLint i = 0;
         glGetRenderbufferParameterivEXT(GL_RENDERBUFFER_EXT, GL_RENDERBUFFER_DEPTH_SIZE_EXT, &i);
         glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
@@ -213,10 +477,18 @@ void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::At
 
     glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
     if (!valid) {
-        glDeleteTextures(1, &texture);
+        if (color_buffer)
+            glDeleteRenderbuffersEXT(1, &color_buffer);
+        else
+            glDeleteTextures(1, &texture);
         glDeleteFramebuffersEXT(1, &fbo);
     }
     QT_CHECK_GLERROR();
+
+    format.setTextureTarget(target);
+    format.setSamples(samples);
+    format.setAttachment(fbo_attachment);
+    format.setInternalFormat(internal_format);
 }
 
 /*!
@@ -264,13 +536,18 @@ void QGLFramebufferObjectPrivate::init(const QSize &sz, QGLFramebufferObject::At
     framebuffer objects more portable.
     \endlist
 
-    Note that primitives drawn to a QGLFramebufferObject with QPainter
-    will only be antialiased if the QPainter::HighQualityAntialiasing
-    render hint is set. This is because there is currently no support
-    for the \c{GL_EXT_framebuffer_multisample} extension, which is
-    required to do multisample based antialiasing. Also note that the
-    QPainter::HighQualityAntialiasing render hint requires the
-    \c{GL_ARB_fragment_program} extension to work in OpenGL.
+    Note that you need to create a QGLFramebufferObject with more than one
+    sample per pixel for primitives to be antialiased when drawing using a
+    QPainter, unless if the QPainter::HighQualityAntialiasing render hint is
+    set. The QPainter::HighQualityAntialiasing render hint will enable
+    antialiasing as long as the \c{GL_ARB_fragment_program} extension is
+    present. To create a multisample framebuffer object you should use one of
+    the constructors that take a QGLFramebufferObject parameter, and set the
+    QGLFramebufferObject::samples() property to a non-zero value.
+
+    If you want to use a framebuffer object with multisampling enabled
+    as a texture, you first need to copy from it to a regular framebuffer
+    object using QGLContext::blitFramebuffer().
 
     \sa {Framebuffer Object Example}
 */
@@ -358,6 +635,32 @@ QGLFramebufferObject::QGLFramebufferObject(int width, int height, GLenum target)
     d->init(QSize(width, height), NoAttachment, target, DEFAULT_FORMAT);
 }
 
+/*! \overload
+
+    Constructs an OpenGL framebuffer object of the given \a size based on the
+    supplied \a format.
+*/
+
+QGLFramebufferObject::QGLFramebufferObject(const QSize &size, const QGLFramebufferObjectFormat &format)
+    : d_ptr(new QGLFramebufferObjectPrivate)
+{
+    Q_D(QGLFramebufferObject);
+    d->init(size, format.attachment(), format.textureTarget(), format.internalFormat(), format.samples());
+}
+
+/*! \overload
+
+    Constructs an OpenGL framebuffer object of the given \a width and \a height
+    based on the supplied \a format.
+*/
+
+QGLFramebufferObject::QGLFramebufferObject(int width, int height, const QGLFramebufferObjectFormat &format)
+    : d_ptr(new QGLFramebufferObjectPrivate)
+{
+    Q_D(QGLFramebufferObject);
+    d->init(QSize(width, height), format.attachment(), format.textureTarget(), format.internalFormat(), format.samples());
+}
+
 #ifdef Q_MAC_COMPAT_GL_FUNCTIONS
 /*! \internal */
 QGLFramebufferObject::QGLFramebufferObject(int width, int height, QMacCompatGLenum target)
@@ -445,6 +748,8 @@ QGLFramebufferObject::~QGLFramebufferObject()
             || qgl_share_reg()->checkSharing(d->ctx, QGLContext::currentContext())))
     {
         glDeleteTextures(1, &d->texture);
+        if (d->color_buffer)
+            glDeleteRenderbuffersEXT(1, &d->color_buffer);
         if (d->depth_stencil_buffer)
             glDeleteRenderbuffersEXT(1, &d->depth_stencil_buffer);
         glDeleteFramebuffersEXT(1, &d->fbo);
@@ -540,6 +845,9 @@ bool QGLFramebufferObject::release()
     Returns the texture id for the texture attached as the default
     rendering target in this framebuffer object. This texture id can
     be bound as a normal texture in your own GL code.
+
+    If a multisample framebuffer object is used then the value returned
+    from this function will be invalid.
 */
 GLuint QGLFramebufferObject::texture() const
 {
@@ -560,6 +868,15 @@ QSize QGLFramebufferObject::size() const
 }
 
 /*!
+    Returns the format of this framebuffer object.
+*/
+const QGLFramebufferObjectFormat &QGLFramebufferObject::format() const
+{
+    Q_D(const QGLFramebufferObject);
+    return d->format;
+}
+
+/*!
     \fn QImage QGLFramebufferObject::toImage() const
 
     Returns the contents of this framebuffer object as a QImage.
@@ -752,4 +1069,85 @@ bool QGLFramebufferObject::isBound() const
     return d->bound;
 }
 
+/*!
+    \fn bool QGLFramebufferObject::hasOpenGLFramebufferBlit()
+
+    \since 4.6
+
+    Returns true if the OpenGL \c{GL_EXT_framebuffer_blit} extension
+    is present on this system; otherwise returns false.
+*/
+bool QGLFramebufferObject::hasOpenGLFramebufferBlit()
+{
+    QGLWidget dmy; // needed to detect and init the QGLExtensions object
+    return (QGLExtensions::glExtensions & QGLExtensions::FramebufferBlit);
+}
+
+/*!
+    \since 4.6
+
+    Blits from the \a sourceRect rectangle in the \a source framebuffer
+    object to the \a targetRect rectangle in the \a target framebuffer object.
+
+    If \a source or \a target is 0, the default framebuffer will be used
+    instead of a framebuffer object as source or target respectively.
+
+    The \a buffers parameter should be a mask consisting of any combination of
+    COLOR_BUFFER_BIT, DEPTH_BUFFER_BIT, and STENCIL_BUFFER_BIT. Any buffer type
+    that is not present both in the source and target buffers is ignored.
+
+    The \a sourceRect and \a targetRect rectangles may have different sizes;
+    in this case \a buffers should not contain DEPTH_BUFFER_BIT or
+    STENCIL_BUFFER_BIT. The \a filter parameter should be set to GL_LINEAR or
+    GL_NEAREST, and specifies whether linear or nearest interpolation should
+    be used when scaling is performed.
+
+    If \a source equals \a target a copy is performed within the same buffer.
+    Results are undefined if the source and target rectangles overlap and
+    have different sizes. The sizes must also be the same if any of the
+    framebuffer objects are multisample framebuffers.
+
+    Note that the scissor test will restrict the blit area if enabled.
+
+    This function will have no effect unless hasOpenGLFramebufferBlit() returns
+    true.
+*/
+void QGLFramebufferObject::blitFramebuffer(QGLFramebufferObject *target, const QRect &targetRect,
+                                           QGLFramebufferObject *source, const QRect &sourceRect,
+                                           GLbitfield buffers,
+                                           GLenum filter)
+{
+    if (!(QGLExtensions::glExtensions & QGLExtensions::FramebufferBlit))
+        return;
+
+    const QGLContext *ctx = QGLContext::currentContext();
+    if (!ctx)
+        return;
+
+    const int height = ctx->device()->height();
+
+    const int sh = source ? source->height() : height;
+    const int th = target ? target->height() : height;
+
+    const int sx0 = sourceRect.left();
+    const int sx1 = sourceRect.right();
+    const int sy0 = sh - sourceRect.bottom() - 1;
+    const int sy1 = sh - sourceRect.top() - 1;
+
+    const int tx0 = targetRect.left();
+    const int tx1 = targetRect.right();
+    const int ty0 = th - targetRect.bottom() - 1;
+    const int ty1 = th - targetRect.top() - 1;
+
+    glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, source ? source->handle() : 0);
+    glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, target ? target->handle() : 0);
+
+    glBlitFramebufferEXT(sx0, sy0, sx1, sy1,
+                         tx0, ty0, tx1, ty1,
+                         buffers, filter);
+
+    glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, 0);
+    glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, 0);
+}
+
 QT_END_NAMESPACE
diff --git a/src/opengl/qglframebufferobject.h b/src/opengl/qglframebufferobject.h
index a9e1b2f..0a2a9d2 100644
--- a/src/opengl/qglframebufferobject.h
+++ b/src/opengl/qglframebufferobject.h
@@ -52,6 +52,7 @@ QT_BEGIN_NAMESPACE
 QT_MODULE(OpenGL)
 
 class QGLFramebufferObjectPrivate;
+class QGLFramebufferObjectFormat;
 
 class Q_OPENGL_EXPORT QGLFramebufferObject : public QPaintDevice
 {
@@ -77,6 +78,9 @@ public:
                          GLenum target = GL_TEXTURE_2D, GLenum internal_format = GL_RGBA);
 #endif
 
+    QGLFramebufferObject(const QSize &size, const QGLFramebufferObjectFormat &format);
+    QGLFramebufferObject(int width, int height, const QGLFramebufferObjectFormat &format);
+
 #ifdef Q_MAC_COMPAT_GL_FUNCTIONS
     QGLFramebufferObject(const QSize &size, QMacCompatGLenum target = GL_TEXTURE_2D);
     QGLFramebufferObject(int width, int height, QMacCompatGLenum target = GL_TEXTURE_2D);
@@ -89,10 +93,13 @@ public:
 
     virtual ~QGLFramebufferObject();
 
+    const QGLFramebufferObjectFormat &format() const;
+
     bool isValid() const;
     bool isBound() const;
     bool bind();
     bool release();
+
     GLuint texture() const;
     QSize size() const;
     QImage toImage() const;
@@ -110,6 +117,12 @@ public:
     void drawTexture(const QPointF &point, QMacCompatGLuint textureId, QMacCompatGLenum textureTarget = GL_TEXTURE_2D);
 #endif
 
+    static bool hasOpenGLFramebufferBlit();
+    static void blitFramebuffer(QGLFramebufferObject *target, const QRect &targetRect,
+                                QGLFramebufferObject *source, const QRect &sourceRect,
+                                GLbitfield buffers = GL_COLOR_BUFFER_BIT,
+                                GLenum filter = GL_NEAREST);
+
 protected:
     int metric(PaintDeviceMetric metric) const;
     int devType() const { return QInternal::FramebufferObject; }
@@ -120,6 +133,42 @@ private:
     friend class QGLDrawable;
 };
 
+class QGLFramebufferObjectFormatPrivate;
+class Q_OPENGL_EXPORT QGLFramebufferObjectFormat
+{
+public:
+#if !defined(QT_OPENGL_ES) || defined(Q_QDOC)
+    QGLFramebufferObjectFormat(int samples = 0,
+                               QGLFramebufferObject::Attachment attachment = QGLFramebufferObject::NoAttachment,
+                               GLenum target = GL_TEXTURE_2D,
+                               GLenum internalFormat = GL_RGBA8);
+#else
+    QGLFramebufferObjectFormat(int samples = 0,
+                               QGLFramebufferObject::Attachment attachment = QGLFramebufferObject::NoAttachment,
+                               GLenum target = GL_TEXTURE_2D,
+                               GLenum internalFormat = GL_RGBA);
+#endif
+
+    QGLFramebufferObjectFormat(const QGLFramebufferObjectFormat &other);
+    QGLFramebufferObjectFormat &operator=(const QGLFramebufferObjectFormat &other);
+    ~QGLFramebufferObjectFormat();
+
+    void setSamples(int samples);
+    int samples() const;
+
+    void setAttachment(QGLFramebufferObject::Attachment attachment);
+    QGLFramebufferObject::Attachment attachment() const;
+
+    void setTextureTarget(GLenum target);
+    GLenum textureTarget() const;
+
+    void setInternalFormat(GLenum internalFormat);
+    GLenum internalFormat() const;
+
+private:
+    QGLFramebufferObjectFormatPrivate *d;
+};
+
 QT_END_NAMESPACE
 
 QT_END_HEADER