Return the correct QGLFormat to the OpenGL1 paint engine for FBO's

QGLPaintDevice::format() was returning the context's format, not
the format of the window surface's FBO.  This caused the OpenGL1
paint engine to think that the window didn't have depth and
stencil buffers, even though the FBO most certainly did.

This change makes QGLPaintDevice::format() virtual and overrides it
in QGLFBOGLPaintDevice to return an updated format that includes
the context parameters plus the extra features that the FBO supports.

Reviewed-by: Tom Cooksey

3 files changed, 18 insertions, 4 deletions

diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index 094f675..f15aa01 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -299,10 +299,21 @@ bool QGLFramebufferObjectFormat::operator!=(const QGLFramebufferObjectFormat& ot
     return !(*this == other);
 }
 
-void QGLFBOGLPaintDevice::setFBO(QGLFramebufferObject* f)
+void QGLFBOGLPaintDevice::setFBO(QGLFramebufferObject* f,
+                                 QGLFramebufferObject::Attachment attachment)
 {
     fbo = f;
     m_thisFBO = fbo->d_func()->fbo; // This shouldn't be needed
+
+    // The context that the fbo was created in may not have depth
+    // and stencil buffers, but the fbo itself might.
+    fboFormat = QGLContext::currentContext()->format();
+    if (attachment == QGLFramebufferObject::CombinedDepthStencil) {
+        fboFormat.setDepth(true);
+        fboFormat.setStencil(true);
+    } else if (attachment == QGLFramebufferObject::Depth) {
+        fboFormat.setDepth(true);
+    }
 }
 
 void QGLFBOGLPaintDevice::ensureActiveTarget()
@@ -395,7 +406,7 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
     glGenFramebuffers(1, &fbo);
     glBindFramebuffer(GL_FRAMEBUFFER_EXT, fbo);
 
-    glDevice.setFBO(q);
+    glDevice.setFBO(q, attachment);
 
     QT_CHECK_GLERROR();
     // init texture
diff --git a/src/opengl/qglframebufferobject_p.h b/src/opengl/qglframebufferobject_p.h
index c11c496..f80209d 100644
--- a/src/opengl/qglframebufferobject_p.h
+++ b/src/opengl/qglframebufferobject_p.h
@@ -110,15 +110,18 @@ public:
     virtual QPaintEngine* paintEngine() const {return fbo->paintEngine();}
     virtual QSize size() const {return fbo->size();}
     virtual QGLContext* context() const {return const_cast<QGLContext *>(QGLContext::currentContext());}
+    virtual QGLFormat format() const {return fboFormat;}
     virtual void ensureActiveTarget();
     virtual void beginPaint();
     virtual void endPaint();
 
-    void setFBO(QGLFramebufferObject* f);
+    void setFBO(QGLFramebufferObject* f,
+                QGLFramebufferObject::Attachment attachment);
 
 private:
     bool wasBound;
     QGLFramebufferObject* fbo;
+    QGLFormat fboFormat;
 };
 
 class QGLFramebufferObjectPrivate
diff --git a/src/opengl/qglpaintdevice_p.h b/src/opengl/qglpaintdevice_p.h
index 66b24a9..1e7ba8d 100644
--- a/src/opengl/qglpaintdevice_p.h
+++ b/src/opengl/qglpaintdevice_p.h
@@ -73,7 +73,7 @@ public:
     virtual void endPaint();
 
     virtual QGLContext* context() const = 0;
-    QGLFormat format() const;
+    virtual QGLFormat format() const;
     virtual QSize size() const = 0;
 
     // returns the QGLPaintDevice for the given QPaintDevice