Avoid repeated QByteArray creation when resolving opengl functions

Add an getProcAddress(const char *) overload to QOpenGLContext,
and refactor the QPA interface to take a const char *. Like this
we can avoid lots of mallocs when resoving GL methods.

Change-Id: Ic45b985fbaa0da8d32ba3e3b485351173352ca6f
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

4 files changed, 14 insertions, 5 deletions

diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index b45396ab3c..f301b21ec1 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -1070,9 +1070,18 @@ void QOpenGLContext::swapBuffers(QSurface *surface)
 */
 QFunctionPointer QOpenGLContext::getProcAddress(const QByteArray &procName) const
 {
+    return getProcAddress(procName.constData());
+}
+
+/*!
+  \overload
+  \since 5.8
+ */
+QFunctionPointer QOpenGLContext::getProcAddress(const char *procName) const
+{
     Q_D(const QOpenGLContext);
     if (!d->platformGLContext)
-        return 0;
+        return nullptr;
     return d->platformGLContext->getProcAddress(procName);
 }
 
diff --git a/src/gui/kernel/qopenglcontext.h b/src/gui/kernel/qopenglcontext.h
index 56eb6f0e12..130d55464f 100644
--- a/src/gui/kernel/qopenglcontext.h
+++ b/src/gui/kernel/qopenglcontext.h
@@ -174,6 +174,7 @@ public:
 
     void swapBuffers(QSurface *surface);
     QFunctionPointer getProcAddress(const QByteArray &procName) const;
+    QFunctionPointer getProcAddress(const char *procName) const;
 
     QSurface *surface() const;
 
diff --git a/src/gui/kernel/qplatformopenglcontext.cpp b/src/gui/kernel/qplatformopenglcontext.cpp
index 2457a5237d..5b375f7883 100644
--- a/src/gui/kernel/qplatformopenglcontext.cpp
+++ b/src/gui/kernel/qplatformopenglcontext.cpp
@@ -71,10 +71,9 @@ QT_BEGIN_NAMESPACE
     The implementation must support being called in a thread different than the gui-thread.
 */
 
-/*! \fn QFunctionPointer QPlatformOpenGLContext::getProcAddress(const QByteArray &procName)
-    Reimplement in subclass to native getProcAddr calls.
+/*! \fn QFunctionPointer QPlatformOpenGLContext::getProcAddress(const char *procName)
 
-    Note: its convenient to use qPrintable(const QString &str) to get the const char * pointer
+    Reimplement in subclass to native getProcAddr calls.
 */
 
 class QPlatformOpenGLContextPrivate
diff --git a/src/gui/kernel/qplatformopenglcontext.h b/src/gui/kernel/qplatformopenglcontext.h
index f2ec1c1a7e..1a38a5fed3 100644
--- a/src/gui/kernel/qplatformopenglcontext.h
+++ b/src/gui/kernel/qplatformopenglcontext.h
@@ -83,7 +83,7 @@ public:
     virtual bool isSharing() const { return false; }
     virtual bool isValid() const { return true; }
 
-    virtual QFunctionPointer getProcAddress(const QByteArray &procName) = 0;
+    virtual QFunctionPointer getProcAddress(const char *procName) = 0;
 
     QOpenGLContext *context() const;