Reverted use of GL 2 engine as default on desktop.

Using GL 2 as default engine breaks the use cases where OpenGL commands
are inter-mixed with QPainter commands, such as when using raw OpenGL in
graphicsview.

For now we'll use the old OpenGL engine for QGLWidget, QGLPixelBuffer,
and QGLFramebufferObject on desktop, and the OpenGL 2 paint engine when
the OpenGL graphics system is used.

Reviewed-by: Trond

6 files changed, 15 insertions, 27 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 779ed9a..12f781e 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -1366,7 +1366,7 @@ QImage qt_gl_read_texture(const QSize &size, bool alpha_format, bool include_alp
     int w = size.width();
     int h = size.height();
 #if !defined(QT_OPENGL_ES_2) //### glGetTexImage not in GL ES 2.0, need to do something else here!
-    glGetTexImage(qt_gl_preferredTextureTarget(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
+    glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
 #endif
     convertFromGLImage(img, w, h, alpha_format, include_alpha);
     return img;
@@ -1971,7 +1971,7 @@ GLuint QGLContextPrivate::bindTexture(const QPixmap &pixmap, GLenum target, GLin
 {
     Q_Q(QGLContext);
     QPixmapData *pd = pixmap.pixmapData();
-    if (target == qt_gl_preferredTextureTarget() && pd->classId() == QPixmapData::OpenGLClass) {
+    if (target == GL_TEXTURE_2D && pd->classId() == QPixmapData::OpenGLClass) {
         const QGLPixmapData *data = static_cast<const QGLPixmapData *>(pd);
 
         if (data->isValidContext(q))
diff --git a/src/opengl/qgl_p.h b/src/opengl/qgl_p.h
index 1513ee8..a294af9 100644
--- a/src/opengl/qgl_p.h
+++ b/src/opengl/qgl_p.h
@@ -424,9 +424,8 @@ inline bool qt_gl_preferGL2Engine()
 #if defined(QT_OPENGL_ES_2)
     return true;
 #else
-    QGLFormat::OpenGLVersionFlags flags = QGLFormat::openGLVersionFlags();
-    bool hasOpenGL2 = (flags & QGLFormat::OpenGL_Version_2_0);
-    return hasOpenGL2 && qgetenv("QT_GL_NO_OPENGL2ENGINE").isEmpty();
+    return (QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_2_0)
+           && !qgetenv("QT_GL_USE_OPENGL2ENGINE").isEmpty();
 #endif
 }
 
diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index 87e0dda..5f106ff 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -906,8 +906,9 @@ Q_GLOBAL_STATIC(QOpenGLPaintEngine, qt_buffer_engine)
 /*! \reimp */
 QPaintEngine *QGLFramebufferObject::paintEngine() const
 {
+    Q_D(const QGLFramebufferObject);
 #if !defined(QT_OPENGL_ES_2)
-    if (qt_gl_preferGL2Engine())
+    if (d->ctx->d_func()->internal_context || qt_gl_preferGL2Engine())
         return qt_buffer_2_engine();
     else
         return qt_buffer_engine();
diff --git a/src/opengl/qglpixelbuffer.cpp b/src/opengl/qglpixelbuffer.cpp
index cb24177..00b58d3 100644
--- a/src/opengl/qglpixelbuffer.cpp
+++ b/src/opengl/qglpixelbuffer.cpp
@@ -375,7 +375,7 @@ Q_GLOBAL_STATIC(QOpenGLPaintEngine, qt_buffer_engine)
 QPaintEngine *QGLPixelBuffer::paintEngine() const
 {
 #if !defined(QT_OPENGL_ES_2)
-    if (qt_gl_preferGL2Engine())
+    if (d_ptr->qctx->d_func()->internal_context || qt_gl_preferGL2Engine())
         return qt_buffer_2_engine();
     else
         return qt_buffer_engine();
diff --git a/src/opengl/qpixmapdata_gl.cpp b/src/opengl/qpixmapdata_gl.cpp
index 89e6749..e3af864 100644
--- a/src/opengl/qpixmapdata_gl.cpp
+++ b/src/opengl/qpixmapdata_gl.cpp
@@ -160,7 +160,7 @@ void QGLPixmapData::ensureCreated() const
     m_ctx = ctx;
 
     const GLenum format = qt_gl_preferredTextureFormat();
-    const GLenum target = qt_gl_preferredTextureTarget();
+    const GLenum target = GL_TEXTURE_2D;
 
     if (!m_textureId) {
         glGenTextures(1, &m_textureId);
@@ -252,7 +252,7 @@ QImage QGLPixmapData::toImage() const
 
     QGLShareContextScope ctx(qt_gl_share_widget()->context());
     extern QImage qt_gl_read_texture(const QSize &size, bool alpha_format, bool include_alpha);
-    glBindTexture(qt_gl_preferredTextureTarget(), m_textureId);
+    glBindTexture(GL_TEXTURE_2D, m_textureId);
     return qt_gl_read_texture(QSize(m_width, m_height), true, true);
 }
 
@@ -280,7 +280,7 @@ void QGLPixmapData::copyBackFromRenderFbo(bool keepCurrentFboBound) const
 
     glBindFramebuffer(GL_FRAMEBUFFER_EXT, ctx->d_ptr->fbo);
     glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
-        qt_gl_preferredTextureTarget(), m_textureId, 0);
+        GL_TEXTURE_2D, m_textureId, 0);
 
     const int x0 = 0;
     const int x1 = m_width;
@@ -398,7 +398,7 @@ GLuint QGLPixmapData::bind(bool copyBack) const
         ensureCreated();
 
     GLuint id = m_textureId;
-    glBindTexture(qt_gl_preferredTextureTarget(), id);
+    glBindTexture(GL_TEXTURE_2D, id);
     return id;
 }
 
diff --git a/src/opengl/qwindowsurface_gl.cpp b/src/opengl/qwindowsurface_gl.cpp
index c732174..6fce3e3 100644
--- a/src/opengl/qwindowsurface_gl.cpp
+++ b/src/opengl/qwindowsurface_gl.cpp
@@ -72,10 +72,6 @@
 
 #include <private/qpaintengineex_opengl2_p.h>
 
-#ifndef QT_OPENGL_ES_2
-#include <private/qpaintengine_opengl_p.h>
-#endif
-
 #ifndef GLX_ARB_multisample
 #define GLX_SAMPLE_BUFFERS_ARB  100000
 #define GLX_SAMPLES_ARB         100001
@@ -295,17 +291,9 @@ void QGLWindowSurface::hijackWindow(QWidget *widget)
 
 Q_GLOBAL_STATIC(QGL2PaintEngineEx, qt_gl_window_surface_2_engine)
 
-#ifndef QT_OPENGL_ES_2
-Q_GLOBAL_STATIC(QOpenGLPaintEngine, qt_gl_window_surface_engine)
-#endif
-
 /*! \reimp */
 QPaintEngine *QGLWindowSurface::paintEngine() const
 {
-#if !defined(QT_OPENGL_ES_2)
-    if (!qt_gl_preferGL2Engine())
-        return qt_gl_window_surface_engine();
-#endif
     return qt_gl_window_surface_2_engine();
 }
 
@@ -361,7 +349,7 @@ void QGLWindowSurface::flush(QWidget *widget, const QRegion &rgn, const QPoint &
     QPoint wOffset = qt_qwidget_data(parent)->wrect.topLeft();
     QRect rect = br.translated(-offset - wOffset);
 
-    const GLenum target = qt_gl_preferredTextureTarget();
+    const GLenum target = GL_TEXTURE_2D;
 
     if (context()) {
         context()->makeCurrent();
@@ -502,7 +490,7 @@ void QGLWindowSurface::updateGeometry()
 {
     QRect rect = QWindowSurface::geometry();
 
-    const GLenum target = qt_gl_preferredTextureTarget();
+    const GLenum target = GL_TEXTURE_2D;
 
     if (rect.width() <= 0 || rect.height() <= 0)
         return;
@@ -643,7 +631,7 @@ bool QGLWindowSurface::scroll(const QRegion &area, int dx, int dy)
     return true;
 #endif
 
-    const GLenum target = qt_gl_preferredTextureTarget();
+    const GLenum target = GL_TEXTURE_2D;
 
     glBindTexture(target, d_ptr->tex_id);
     glCopyTexImage2D(target, 0, GL_RGBA, br.x(), d_ptr->pb->height() - (br.y() + br.height()), br.width(), br.height(), 0);
@@ -656,7 +644,7 @@ bool QGLWindowSurface::scroll(const QRegion &area, int dx, int dy)
 
 static void drawTexture(const QRectF &rect, GLuint tex_id, const QSize &texSize, const QRectF &br)
 {
-    const GLenum target = qt_gl_preferredTextureTarget();
+    const GLenum target = GL_TEXTURE_2D;
     QRectF src = br.isEmpty()
         ? QRectF(QPointF(), texSize)
         : QRectF(QPointF(br.x(), texSize.height() - br.bottom()), br.size());