Dynamic GL switch on Windows

The patch introduces a new build configuration on Windows which
can be requested by passing -opengl dynamic to configure.

Platforms other than Windows (including WinRT) are not affected.
The existing Angle and desktop configurations are not affected.
These continue to function as before and Angle remains the default.

In the future, when all modules have added support for the dynamic
path, as described below, the default configuration could be changed
to be the dynamic one. This would allow providing a single set of
binaries in the official builds instead of the current two.

When requesting dynamic GL, Angle is built but QT_OPENGL_ES[_2] are
never defined. Instead, the code path that has traditionally been
desktop GL only becomes the dynamic path that has to do runtime
checks. Qt modules and applications are not linked to opengl32.dll or
libegl/glesv2.dll in this case. Instead, QtGui exports all necessary
egl/egl/gl functions which will, under the hood, forward all requests
to a dynamically loaded EGL/WGL/GL implementation.

Porting guide (better said, changes needed to prepare your code to
work with dynamic GL builds when the fallback to Angle is utilized):

1. In !QT_OPENGL_ES[_2] code branches use QOpenGLFunctions::isES() to
differentiate between desktop and ES where needed. Keep in mind that
it is the desktop GL header (plus qopenglext.h) that is included,
not the GLES one.

QtGui's proxy will handle some differences, for example calling
glClearDepth will route to glClearDepthf when needed. The built-in
eglGetProcAddress is able to retrieve pointers for standard GLES2
functions too so code resolving OpenGL 2 functions will function
in any case.

2. QT_CONFIG will contain "opengl" and "dynamicgl" in dynamic builds,
but never "angle" or "opengles2".

3. The preprocessor define QT_OPENGL_DYNAMIC is also available in
dynamic builds. The usage of this is strongly discouraged and should
not be needed anywhere except for QtGui and the platform plugin.

4. Code in need of the library handle can use
QOpenGLFunctions::platformGLHandle().

The decision on which library to load is currently based on a simple
test that creates a dummy window/context and tries to resolve an
OpenGL 2 function. If this fails, it goes for Angle. This seems to work
well on Win7 PCs for example that do not have proper graphics drivers
providing OpenGL installed but are D3D9 capable using the default drivers.

Setting QT_OPENGL to desktop or angle skips the test and forces
usage of the given GL. There are also two new application attributes
that could be used for the same purpose.

If Angle is requested but the libraries are not present, desktop is
tried. If desktop is requested, or if angle is requested but nothing
works, the EGL/WGL functions will still be callable but will return 0.
This conveniently means that eglInitialize() and such will report a failure.

Debug messages can be enabled by setting QT_OPENGLPROXY_DEBUG. This will
tell which implementation is chosen.

The textures example application is ported to OpenGL 2, the GL 1
code path is removed.

[ChangeLog][QtGui] Qt builds on Windows can now be configured for
dynamic loading of the OpenGL implementation. This can be requested
by passing -opengl dynamic to configure. In this mode no modules will
link to opengl32.dll or Angle's libegl/libglesv2. Instead, QtGui will
dynamically choose between desktop and Angle during the first GL/EGL/WGL
call. This allows deploying applications with a single set of Qt libraries
with the ability of transparently falling back to Angle in case the
opengl32.dll is not suitable, due to missing graphics drivers for example.

Task-number: QTBUG-36483
Change-Id: I716fdebbf60b355b7d9ef57d1e069eef366b4ab9
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

1 files changed, 244 insertions, 222 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 40a8b1921c..e027de02e0 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -1699,10 +1699,12 @@ QImage qt_gl_read_texture(const QSize &size, bool alpha_format, bool include_alp
         return QImage();
     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(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
-#endif
+#ifndef QT_OPENGL_ES
+    if (!QOpenGLFunctions::isES()) {
+        //### glGetTexImage not in GL ES 2.0, need to do something else here!
+        glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
+    }
+#endif // QT_OPENGL_ES
     convertFromGLImage(img, w, h, alpha_format, include_alpha);
     return img;
 }
@@ -2282,17 +2284,20 @@ QGLTexture* QGLContextPrivate::bindTexture(const QImage &image, GLenum target, G
     glBindTexture(target, tx_id);
     glTexParameteri(target, GL_TEXTURE_MAG_FILTER, filtering);
 
-#if defined(QT_OPENGL_ES_2)
-    bool genMipmap = false;
-#endif
+    bool genMipmap = !QOpenGLFunctions::isES();
     if (glFormat.directRendering()
         && (qgl_extensions()->hasOpenGLExtension(QOpenGLExtensions::GenerateMipmap))
         && target == GL_TEXTURE_2D
         && (options & QGLContext::MipmapBindOption))
     {
 #if !defined(QT_OPENGL_ES_2)
-        glHint(GL_GENERATE_MIPMAP_HINT_SGIS, GL_NICEST);
-        glTexParameteri(target, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
+        if (genMipmap) {
+            glHint(GL_GENERATE_MIPMAP_HINT_SGIS, GL_NICEST);
+            glTexParameteri(target, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
+        } else {
+            glHint(GL_GENERATE_MIPMAP_HINT, GL_NICEST);
+            genMipmap = true;
+        }
 #else
         glHint(GL_GENERATE_MIPMAP_HINT, GL_NICEST);
         genMipmap = true;
@@ -2421,11 +2426,11 @@ QGLTexture* QGLContextPrivate::bindTexture(const QImage &image, GLenum target, G
             printf(" - did byte swapping (%d ms)\n", time.elapsed());
 #endif
     }
-#ifdef QT_OPENGL_ES
-    // OpenGL/ES requires that the internal and external formats be
-    // identical.
-    internalFormat = externalFormat;
-#endif
+    if (QOpenGLFunctions::isES()) {
+        // OpenGL/ES requires that the internal and external formats be
+        // identical.
+        internalFormat = externalFormat;
+    }
 #ifdef QGL_BIND_TEXTURE_DEBUG
     printf(" - uploading, image.format=%d, externalFormat=0x%x, internalFormat=0x%x, pixel_type=0x%x\n",
            img.format(), externalFormat, internalFormat, pixel_type);
@@ -2434,10 +2439,8 @@ QGLTexture* QGLContextPrivate::bindTexture(const QImage &image, GLenum target, G
     const QImage &constRef = img; // to avoid detach in bits()...
     glTexImage2D(target, 0, internalFormat, img.width(), img.height(), 0, externalFormat,
                  pixel_type, constRef.bits());
-#if defined(QT_OPENGL_ES_2)
-    if (genMipmap)
-        glGenerateMipmap(target);
-#endif
+    if (genMipmap && QOpenGLFunctions::isES())
+        functions->glGenerateMipmap(target);
 #ifndef QT_NO_DEBUG
     GLenum error = glGetError();
     if (error != GL_NO_ERROR) {
@@ -2518,31 +2521,32 @@ int QGLContextPrivate::maxTextureSize()
 
     glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_texture_size);
 
-#if defined(QT_OPENGL_ES)
-    return max_texture_size;
-#else
-    GLenum proxy = GL_PROXY_TEXTURE_2D;
-
-    GLint size;
-    GLint next = 64;
-    glTexImage2D(proxy, 0, GL_RGBA, next, next, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
-    glGetTexLevelParameteriv(proxy, 0, GL_TEXTURE_WIDTH, &size);
-    if (size == 0) {
-        return max_texture_size;
-    }
-    do {
-        size = next;
-        next = size * 2;
+#ifndef QT_OPENGL_ES
+    if (!QOpenGLFunctions::isES()) {
+        GLenum proxy = GL_PROXY_TEXTURE_2D;
 
-        if (next > max_texture_size)
-            break;
+        GLint size;
+        GLint next = 64;
         glTexImage2D(proxy, 0, GL_RGBA, next, next, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
-        glGetTexLevelParameteriv(proxy, 0, GL_TEXTURE_WIDTH, &next);
-    } while (next > size);
+        glGetTexLevelParameteriv(proxy, 0, GL_TEXTURE_WIDTH, &size);
+        if (size == 0) {
+            return max_texture_size;
+        }
+        do {
+            size = next;
+            next = size * 2;
 
-    max_texture_size = size;
-    return max_texture_size;
+            if (next > max_texture_size)
+                break;
+            glTexImage2D(proxy, 0, GL_RGBA, next, next, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+            glGetTexLevelParameteriv(proxy, 0, GL_TEXTURE_WIDTH, &next);
+        } while (next > size);
+
+        max_texture_size = size;
+    }
 #endif
+
+    return max_texture_size;
 }
 
 /*!
@@ -2696,7 +2700,7 @@ static void qDrawTextureRect(const QRectF &target, GLint textureWidth, GLint tex
     Q_UNUSED(textureHeight);
     Q_UNUSED(textureTarget);
 #else
-    if (textureTarget != GL_TEXTURE_2D) {
+    if (textureTarget != GL_TEXTURE_2D && !QOpenGLFunctions::isES()) {
         if (textureWidth == -1 || textureHeight == -1) {
             glGetTexLevelParameteriv(textureTarget, 0, GL_TEXTURE_WIDTH, &textureWidth);
             glGetTexLevelParameteriv(textureTarget, 0, GL_TEXTURE_HEIGHT, &textureHeight);
@@ -2763,35 +2767,38 @@ void QGLContext::drawTexture(const QRectF &target, GLuint textureId, GLenum text
 #endif
 
 #ifndef QT_OPENGL_ES_2
+    if (!QOpenGLFunctions::isES()) {
 #ifdef QT_OPENGL_ES
-    if (textureTarget != GL_TEXTURE_2D) {
-        qWarning("QGLContext::drawTexture(): texture target must be GL_TEXTURE_2D on OpenGL ES");
-        return;
-    }
+        if (textureTarget != GL_TEXTURE_2D) {
+            qWarning("QGLContext::drawTexture(): texture target must be GL_TEXTURE_2D on OpenGL ES");
+            return;
+        }
 #else
-    const bool wasEnabled = glIsEnabled(GL_TEXTURE_2D);
-    GLint oldTexture;
-    glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldTexture);
+        const bool wasEnabled = glIsEnabled(GL_TEXTURE_2D);
+        GLint oldTexture;
+        glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldTexture);
 #endif
 
-    glEnable(textureTarget);
-    glBindTexture(textureTarget, textureId);
+        glEnable(textureTarget);
+        glBindTexture(textureTarget, textureId);
 
-    qDrawTextureRect(target, -1, -1, textureTarget);
+        qDrawTextureRect(target, -1, -1, textureTarget);
 
 #ifdef QT_OPENGL_ES
-    glDisable(textureTarget);
-#else
-    if (!wasEnabled)
         glDisable(textureTarget);
-    glBindTexture(textureTarget, oldTexture);
+#else
+        if (!wasEnabled)
+            glDisable(textureTarget);
+        glBindTexture(textureTarget, oldTexture);
 #endif
+        return;
+    }
 #else
     Q_UNUSED(target);
     Q_UNUSED(textureId);
     Q_UNUSED(textureTarget);
-    qWarning("drawTexture() with OpenGL ES 2.0 requires an active OpenGL2 paint engine");
 #endif
+    qWarning("drawTexture() with OpenGL ES 2.0 requires an active OpenGL2 paint engine");
 }
 
 /*!
@@ -2821,40 +2828,42 @@ void QGLContext::drawTexture(const QPointF &point, GLuint textureId, GLenum text
     Q_UNUSED(point);
     Q_UNUSED(textureId);
     Q_UNUSED(textureTarget);
-    qWarning("drawTexture(const QPointF &point, GLuint textureId, GLenum textureTarget) not supported with OpenGL ES, use rect version instead");
 #else
-
-    const bool wasEnabled = glIsEnabled(GL_TEXTURE_2D);
-    GLint oldTexture;
-    glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldTexture);
-
-    glEnable(textureTarget);
-    glBindTexture(textureTarget, textureId);
-
-    GLint textureWidth;
-    GLint textureHeight;
-
-    glGetTexLevelParameteriv(textureTarget, 0, GL_TEXTURE_WIDTH, &textureWidth);
-    glGetTexLevelParameteriv(textureTarget, 0, GL_TEXTURE_HEIGHT, &textureHeight);
-
-    if (d_ptr->active_engine &&
-        d_ptr->active_engine->type() == QPaintEngine::OpenGL2) {
-        QGL2PaintEngineEx *eng = static_cast<QGL2PaintEngineEx*>(d_ptr->active_engine);
-        if (!eng->isNativePaintingActive()) {
-            QRectF dest(point, QSizeF(textureWidth, textureHeight));
-            QRectF src(0, 0, textureWidth, textureHeight);
-            QSize size(textureWidth, textureHeight);
-            if (eng->drawTexture(dest, textureId, size, src))
-                return;
+    if (!QOpenGLFunctions::isES()) {
+        const bool wasEnabled = glIsEnabled(GL_TEXTURE_2D);
+        GLint oldTexture;
+        glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldTexture);
+
+        glEnable(textureTarget);
+        glBindTexture(textureTarget, textureId);
+
+        GLint textureWidth;
+        GLint textureHeight;
+
+        glGetTexLevelParameteriv(textureTarget, 0, GL_TEXTURE_WIDTH, &textureWidth);
+        glGetTexLevelParameteriv(textureTarget, 0, GL_TEXTURE_HEIGHT, &textureHeight);
+
+        if (d_ptr->active_engine &&
+            d_ptr->active_engine->type() == QPaintEngine::OpenGL2) {
+            QGL2PaintEngineEx *eng = static_cast<QGL2PaintEngineEx*>(d_ptr->active_engine);
+            if (!eng->isNativePaintingActive()) {
+                QRectF dest(point, QSizeF(textureWidth, textureHeight));
+                QRectF src(0, 0, textureWidth, textureHeight);
+                QSize size(textureWidth, textureHeight);
+                if (eng->drawTexture(dest, textureId, size, src))
+                    return;
+            }
         }
-    }
 
-    qDrawTextureRect(QRectF(point, QSizeF(textureWidth, textureHeight)), textureWidth, textureHeight, textureTarget);
+        qDrawTextureRect(QRectF(point, QSizeF(textureWidth, textureHeight)), textureWidth, textureHeight, textureTarget);
 
-    if (!wasEnabled)
-        glDisable(textureTarget);
-    glBindTexture(textureTarget, oldTexture);
+        if (!wasEnabled)
+            glDisable(textureTarget);
+        glBindTexture(textureTarget, oldTexture);
+        return;
+    }
 #endif
+    qWarning("drawTexture(const QPointF &point, GLuint textureId, GLenum textureTarget) not supported with OpenGL ES, use rect version instead");
 }
 
 /*!
@@ -4163,7 +4172,7 @@ void QGLWidget::glDraw()
         return;
     makeCurrent();
 #ifndef QT_OPENGL_ES
-    if (d->glcx->deviceIsPixmap())
+    if (d->glcx->deviceIsPixmap() && !QOpenGLFunctions::isES())
         glDrawBuffer(GL_FRONT);
 #endif
     QSize readback_target_size = d->glcx->d_ptr->readback_target_size;
@@ -4206,18 +4215,20 @@ void QGLWidget::qglColor(const QColor& c) const
 #ifdef QT_OPENGL_ES
     glColor4f(c.redF(), c.greenF(), c.blueF(), c.alphaF());
 #else
-    Q_D(const QGLWidget);
-    const QGLContext *ctx = QGLContext::currentContext();
-    if (ctx) {
-        if (ctx->format().rgba())
-            glColor4f(c.redF(), c.greenF(), c.blueF(), c.alphaF());
-        else if (!d->cmap.isEmpty()) { // QGLColormap in use?
-            int i = d->cmap.find(c.rgb());
-            if (i < 0)
-                i = d->cmap.findNearest(c.rgb());
-            glIndexi(i);
-        } else
-            glIndexi(ctx->colorIndex(c));
+    if (!QOpenGLFunctions::isES()) {
+        Q_D(const QGLWidget);
+        const QGLContext *ctx = QGLContext::currentContext();
+        if (ctx) {
+            if (ctx->format().rgba())
+                glColor4f(c.redF(), c.greenF(), c.blueF(), c.alphaF());
+            else if (!d->cmap.isEmpty()) { // QGLColormap in use?
+                int i = d->cmap.find(c.rgb());
+                if (i < 0)
+                    i = d->cmap.findNearest(c.rgb());
+                glIndexi(i);
+            } else
+                glIndexi(ctx->colorIndex(c));
+        }
     }
 #endif //QT_OPENGL_ES
 #else
@@ -4238,18 +4249,23 @@ void QGLWidget::qglClearColor(const QColor& c) const
 #ifdef QT_OPENGL_ES
     glClearColor(c.redF(), c.greenF(), c.blueF(), c.alphaF());
 #else
-    Q_D(const QGLWidget);
-    const QGLContext *ctx = QGLContext::currentContext();
-    if (ctx) {
-        if (ctx->format().rgba())
-            glClearColor(c.redF(), c.greenF(), c.blueF(), c.alphaF());
-        else if (!d->cmap.isEmpty()) { // QGLColormap in use?
-            int i = d->cmap.find(c.rgb());
-            if (i < 0)
-                i = d->cmap.findNearest(c.rgb());
-            glClearIndex(i);
-        } else
-            glClearIndex(ctx->colorIndex(c));
+    if (!QOpenGLFunctions::isES()) {
+        Q_D(const QGLWidget);
+        const QGLContext *ctx = QGLContext::currentContext();
+        if (ctx) {
+            if (ctx->format().rgba())
+                glClearColor(c.redF(), c.greenF(), c.blueF(), c.alphaF());
+            else if (!d->cmap.isEmpty()) { // QGLColormap in use?
+                int i = d->cmap.find(c.rgb());
+                if (i < 0)
+                    i = d->cmap.findNearest(c.rgb());
+                glClearIndex(i);
+            } else {
+                glClearIndex(ctx->colorIndex(c));
+            }
+        }
+    } else {
+        glClearColor(c.redF(), c.greenF(), c.blueF(), c.alphaF());
     }
 #endif
 }
@@ -4411,72 +4427,75 @@ static void qt_gl_draw_text(QPainter *p, int x, int y, const QString &str,
 void QGLWidget::renderText(int x, int y, const QString &str, const QFont &font)
 {
 #ifndef QT_OPENGL_ES
-    Q_D(QGLWidget);
-    if (str.isEmpty() || !isValid())
-        return;
-
-    GLint view[4];
-    bool use_scissor_testing = glIsEnabled(GL_SCISSOR_TEST);
-    if (!use_scissor_testing)
-        glGetIntegerv(GL_VIEWPORT, &view[0]);
-    int width = d->glcx->device()->width();
-    int height = d->glcx->device()->height();
-    bool auto_swap = autoBufferSwap();
-
-    QPaintEngine *engine = paintEngine();
-
-    qt_save_gl_state();
-
-    QPainter *p;
-    bool reuse_painter = false;
-    if (engine->isActive()) {
-        reuse_painter = true;
-        p = engine->painter();
+    if (!QOpenGLFunctions::isES()) {
+        Q_D(QGLWidget);
+        if (str.isEmpty() || !isValid())
+            return;
+
+        GLint view[4];
+        bool use_scissor_testing = glIsEnabled(GL_SCISSOR_TEST);
+        if (!use_scissor_testing)
+            glGetIntegerv(GL_VIEWPORT, &view[0]);
+        int width = d->glcx->device()->width();
+        int height = d->glcx->device()->height();
+        bool auto_swap = autoBufferSwap();
+
+        QPaintEngine *engine = paintEngine();
+
+        qt_save_gl_state();
+
+        QPainter *p;
+        bool reuse_painter = false;
+        if (engine->isActive()) {
+            reuse_painter = true;
+            p = engine->painter();
+
+            glDisable(GL_DEPTH_TEST);
+            glViewport(0, 0, width, height);
+            glMatrixMode(GL_PROJECTION);
+            glLoadIdentity();
+            glOrtho(0, width, height, 0, 0, 1);
+            glMatrixMode(GL_MODELVIEW);
+
+            glLoadIdentity();
+        } else {
+            setAutoBufferSwap(false);
+            // disable glClear() as a result of QPainter::begin()
+            d->disable_clear_on_painter_begin = true;
+            p = new QPainter(this);
+        }
 
-        glDisable(GL_DEPTH_TEST);
-        glViewport(0, 0, width, height);
-        glMatrixMode(GL_PROJECTION);
-        glLoadIdentity();
-        glOrtho(0, width, height, 0, 0, 1);
-        glMatrixMode(GL_MODELVIEW);
+        QRect viewport(view[0], view[1], view[2], view[3]);
+        if (!use_scissor_testing && viewport != rect()) {
+            // if the user hasn't set a scissor box, we set one that
+            // covers the current viewport
+            glScissor(view[0], view[1], view[2], view[3]);
+            glEnable(GL_SCISSOR_TEST);
+        } else if (use_scissor_testing) {
+            // use the scissor box set by the user
+            glEnable(GL_SCISSOR_TEST);
+        }
 
-        glLoadIdentity();
-    } else {
-        setAutoBufferSwap(false);
-        // disable glClear() as a result of QPainter::begin()
-        d->disable_clear_on_painter_begin = true;
-        p = new QPainter(this);
-    }
+        qt_gl_draw_text(p, x, y, str, font);
 
-    QRect viewport(view[0], view[1], view[2], view[3]);
-    if (!use_scissor_testing && viewport != rect()) {
-        // if the user hasn't set a scissor box, we set one that
-        // covers the current viewport
-        glScissor(view[0], view[1], view[2], view[3]);
-        glEnable(GL_SCISSOR_TEST);
-    } else if (use_scissor_testing) {
-        // use the scissor box set by the user
-        glEnable(GL_SCISSOR_TEST);
-    }
+        if (!reuse_painter) {
+            p->end();
+            delete p;
+            setAutoBufferSwap(auto_swap);
+            d->disable_clear_on_painter_begin = false;
+        }
 
-    qt_gl_draw_text(p, x, y, str, font);
+        qt_restore_gl_state();
 
-    if (!reuse_painter) {
-        p->end();
-        delete p;
-        setAutoBufferSwap(auto_swap);
-        d->disable_clear_on_painter_begin = false;
+        return;
     }
-
-    qt_restore_gl_state();
-
 #else // QT_OPENGL_ES
     Q_UNUSED(x);
     Q_UNUSED(y);
     Q_UNUSED(str);
     Q_UNUSED(font);
-    qWarning("QGLWidget::renderText is not supported under OpenGL/ES");
 #endif
+    qWarning("QGLWidget::renderText is not supported under OpenGL/ES");
 }
 
 /*! \overload
@@ -4503,80 +4522,83 @@ void QGLWidget::renderText(int x, int y, const QString &str, const QFont &font)
 void QGLWidget::renderText(double x, double y, double z, const QString &str, const QFont &font)
 {
 #ifndef QT_OPENGL_ES
-    Q_D(QGLWidget);
-    if (str.isEmpty() || !isValid())
-        return;
+    if (!QOpenGLFunctions::isES()) {
+        Q_D(QGLWidget);
+        if (str.isEmpty() || !isValid())
+            return;
+
+        bool auto_swap = autoBufferSwap();
+
+        int width = d->glcx->device()->width();
+        int height = d->glcx->device()->height();
+        GLdouble model[4 * 4], proj[4 * 4];
+        GLint view[4];
+        glGetDoublev(GL_MODELVIEW_MATRIX, &model[0]);
+        glGetDoublev(GL_PROJECTION_MATRIX, &proj[0]);
+        glGetIntegerv(GL_VIEWPORT, &view[0]);
+        GLdouble win_x = 0, win_y = 0, win_z = 0;
+        qgluProject(x, y, z, &model[0], &proj[0], &view[0],
+                    &win_x, &win_y, &win_z);
+        win_y = height - win_y; // y is inverted
 
-    bool auto_swap = autoBufferSwap();
+        QPaintEngine *engine = paintEngine();
 
-    int width = d->glcx->device()->width();
-    int height = d->glcx->device()->height();
-    GLdouble model[4 * 4], proj[4 * 4];
-    GLint view[4];
-    glGetDoublev(GL_MODELVIEW_MATRIX, &model[0]);
-    glGetDoublev(GL_PROJECTION_MATRIX, &proj[0]);
-    glGetIntegerv(GL_VIEWPORT, &view[0]);
-    GLdouble win_x = 0, win_y = 0, win_z = 0;
-    qgluProject(x, y, z, &model[0], &proj[0], &view[0],
-                &win_x, &win_y, &win_z);
-    win_y = height - win_y; // y is inverted
+        QPainter *p;
+        bool reuse_painter = false;
+        bool use_depth_testing = glIsEnabled(GL_DEPTH_TEST);
+        bool use_scissor_testing = glIsEnabled(GL_SCISSOR_TEST);
 
-    QPaintEngine *engine = paintEngine();
+        qt_save_gl_state();
 
-    QPainter *p;
-    bool reuse_painter = false;
-    bool use_depth_testing = glIsEnabled(GL_DEPTH_TEST);
-    bool use_scissor_testing = glIsEnabled(GL_SCISSOR_TEST);
+        if (engine->isActive()) {
+            reuse_painter = true;
+            p = engine->painter();
+        } else {
+            setAutoBufferSwap(false);
+            // disable glClear() as a result of QPainter::begin()
+            d->disable_clear_on_painter_begin = true;
+            p = new QPainter(this);
+        }
 
-    qt_save_gl_state();
+        QRect viewport(view[0], view[1], view[2], view[3]);
+        if (!use_scissor_testing && viewport != rect()) {
+            glScissor(view[0], view[1], view[2], view[3]);
+            glEnable(GL_SCISSOR_TEST);
+        } else if (use_scissor_testing) {
+            glEnable(GL_SCISSOR_TEST);
+        }
+        glMatrixMode(GL_PROJECTION);
+        glLoadIdentity();
+        glViewport(0, 0, width, height);
+        glOrtho(0, width, height, 0, 0, 1);
+        glMatrixMode(GL_MODELVIEW);
+        glLoadIdentity();
+        glAlphaFunc(GL_GREATER, 0.0);
+        glEnable(GL_ALPHA_TEST);
+        if (use_depth_testing)
+            glEnable(GL_DEPTH_TEST);
+        glTranslated(0, 0, -win_z);
+        qt_gl_draw_text(p, qRound(win_x), qRound(win_y), str, font);
+
+        if (!reuse_painter) {
+            p->end();
+            delete p;
+            setAutoBufferSwap(auto_swap);
+            d->disable_clear_on_painter_begin = false;
+        }
 
-    if (engine->isActive()) {
-        reuse_painter = true;
-        p = engine->painter();
-    } else {
-        setAutoBufferSwap(false);
-        // disable glClear() as a result of QPainter::begin()
-        d->disable_clear_on_painter_begin = true;
-        p = new QPainter(this);
-    }
+        qt_restore_gl_state();
 
-    QRect viewport(view[0], view[1], view[2], view[3]);
-    if (!use_scissor_testing && viewport != rect()) {
-        glScissor(view[0], view[1], view[2], view[3]);
-        glEnable(GL_SCISSOR_TEST);
-    } else if (use_scissor_testing) {
-        glEnable(GL_SCISSOR_TEST);
-    }
-    glMatrixMode(GL_PROJECTION);
-    glLoadIdentity();
-    glViewport(0, 0, width, height);
-    glOrtho(0, width, height, 0, 0, 1);
-    glMatrixMode(GL_MODELVIEW);
-    glLoadIdentity();
-    glAlphaFunc(GL_GREATER, 0.0);
-    glEnable(GL_ALPHA_TEST);
-    if (use_depth_testing)
-        glEnable(GL_DEPTH_TEST);
-    glTranslated(0, 0, -win_z);
-    qt_gl_draw_text(p, qRound(win_x), qRound(win_y), str, font);
-
-    if (!reuse_painter) {
-        p->end();
-        delete p;
-        setAutoBufferSwap(auto_swap);
-        d->disable_clear_on_painter_begin = false;
+        return;
     }
-
-    qt_restore_gl_state();
-
 #else // QT_OPENGL_ES
     Q_UNUSED(x);
     Q_UNUSED(y);
     Q_UNUSED(z);
     Q_UNUSED(str);
     Q_UNUSED(font);
-    qWarning("QGLWidget::renderText is not supported under OpenGL/ES");
 #endif
+    qWarning("QGLWidget::renderText is not supported under OpenGL/ES");
 }
 
 QGLFormat QGLWidget::format() const