qt_paint_device_metric() for fetching metrics

Custom window surfaces, graphics systems, and Qt/Embedded screen
drivers often need to access QPaintDevice::metric(), but it is
protected.  Hence the growing number of friends in QWidget and
QImage.  The qt_paint_device_metric() function provides a more
future-proof approach that doesn't require lots of friends.

Reviewed-by: Gunnar

8 files changed, 11 insertions, 34 deletions

diff --git a/src/gui/kernel/qwidget.h b/src/gui/kernel/qwidget.h
index 3501c6e..3cc3093 100644
--- a/src/gui/kernel/qwidget.h
+++ b/src/gui/kernel/qwidget.h
@@ -726,14 +726,11 @@ private:
     friend class QGLContext;
     friend class QGLWidget;
     friend class QGLWindowSurface;
-    friend class QGLWindowSurfaceGLPaintDevice;
-    friend class QVGWindowSurface;
     friend class QX11PaintEngine;
     friend class QWin32PaintEngine;
     friend class QShortcutPrivate;
     friend class QShortcutMap;
     friend class QWindowSurface;
-    friend class QD3DWindowSurface;
     friend class QGraphicsProxyWidget;
     friend class QGraphicsProxyWidgetPrivate;
     friend class QStyleSheetStyle;
diff --git a/src/gui/painting/qpaintdevice.cpp b/src/gui/painting/qpaintdevice.cpp
index 95c0b44..6114938 100644
--- a/src/gui/painting/qpaintdevice.cpp
+++ b/src/gui/painting/qpaintdevice.cpp
@@ -65,4 +65,9 @@ int QPaintDevice::metric(PaintDeviceMetric) const
     return 0;
 }
 
+Q_GUI_EXPORT int qt_paint_device_metric(const QPaintDevice *device, QPaintDevice::PaintDeviceMetric metric)
+{
+    return device->metric(metric);
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/painting/qpaintdevice.h b/src/gui/painting/qpaintdevice.h
index 92aa3cb..c8e86b8 100644
--- a/src/gui/painting/qpaintdevice.h
+++ b/src/gui/painting/qpaintdevice.h
@@ -137,6 +137,7 @@ public:
     friend class QPainter;
     friend class QFontEngineMac;
     friend class QX11PaintEngine;
+    friend Q_GUI_EXPORT int qt_paint_device_metric(const QPaintDevice *device, PaintDeviceMetric metric);
 };
 
 #ifdef QT3_SUPPORT
diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 6037bd5..240403d 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -4213,13 +4213,6 @@ void QRasterBuffer::prepare(QCustomRasterPaintDevice *device)
         drawHelper = qDrawHelper + format;
 }
 
-class MetricAccessor : public QWidget {
-public:
-    int metric(PaintDeviceMetric m) {
-        return QWidget::metric(m);
-    }
-};
-
 int QCustomRasterPaintDevice::metric(PaintDeviceMetric m) const
 {
     switch (m) {
@@ -4231,7 +4224,7 @@ int QCustomRasterPaintDevice::metric(PaintDeviceMetric m) const
         break;
     }
 
-    return (static_cast<MetricAccessor*>(widget)->metric(m));
+    return qt_paint_device_metric(widget, m);
 }
 
 int QCustomRasterPaintDevice::bytesPerLine() const
diff --git a/src/opengl/qglpaintdevice_qws.cpp b/src/opengl/qglpaintdevice_qws.cpp
index 8c2f27d..1512278 100644
--- a/src/opengl/qglpaintdevice_qws.cpp
+++ b/src/opengl/qglpaintdevice_qws.cpp
@@ -52,13 +52,6 @@ public:
     QWidget *widget;
 };
 
-class QMetricAccessor : public QWidget {
-public:
-    int metric(PaintDeviceMetric m) {
-        return QWidget::metric(m);
-    }
-};
-
 QWSGLPaintDevice::QWSGLPaintDevice(QWidget *widget) :
     d_ptr(new QWSGLPaintDevicePrivate)
 {
@@ -80,7 +73,7 @@ int QWSGLPaintDevice::metric(PaintDeviceMetric m) const
     Q_D(const QWSGLPaintDevice);
     Q_ASSERT(d->widget);
 
-    return ((QMetricAccessor *) d->widget)->metric(m);
+    return qt_paint_device_metric(d->widget, m);
 }
 
 QWSGLWindowSurface* QWSGLPaintDevice::windowSurface() const
diff --git a/src/opengl/qwindowsurface_gl.cpp b/src/opengl/qwindowsurface_gl.cpp
index b341243..df84a76 100644
--- a/src/opengl/qwindowsurface_gl.cpp
+++ b/src/opengl/qwindowsurface_gl.cpp
@@ -280,7 +280,7 @@ QGLContext* QGLWindowSurfaceGLPaintDevice::context() const
 
 int QGLWindowSurfaceGLPaintDevice::metric(PaintDeviceMetric m) const
 {
-    return d->q_ptr->window()->metric(m);
+    return qt_paint_device_metric(d->q_ptr->window(), m);
 }
 
 QPaintEngine *QGLWindowSurfaceGLPaintDevice::paintEngine() const
diff --git a/src/openvg/qwindowsurface_vg.cpp b/src/openvg/qwindowsurface_vg.cpp
index 6cc2e27..661e06a 100644
--- a/src/openvg/qwindowsurface_vg.cpp
+++ b/src/openvg/qwindowsurface_vg.cpp
@@ -111,7 +111,7 @@ QPaintEngine *QVGWindowSurface::paintEngine() const
 
 int QVGWindowSurface::metric(PaintDeviceMetric met) const
 {
-    return window()->metric(met);
+    return qt_paint_device_metric(window(), met);
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/graphicssystems/shivavg/shivavgwindowsurface.cpp b/src/plugins/graphicssystems/shivavg/shivavgwindowsurface.cpp
index df623ba..955aa55 100644
--- a/src/plugins/graphicssystems/shivavg/shivavgwindowsurface.cpp
+++ b/src/plugins/graphicssystems/shivavg/shivavgwindowsurface.cpp
@@ -350,21 +350,9 @@ QPaintEngine *ShivaVGWindowSurface::paintEngine() const
     return d_ptr->engine;
 }
 
-// We need to get access to QWidget::metric() from ShivaVGWindowSurface::metric,
-// but it is not a friend of QWidget.  To get around this, we create a
-// fake QX11PaintEngine class, which is a friend.
-class QX11PaintEngine
-{
-public:
-    static int metric(const QWidget *widget, QPaintDevice::PaintDeviceMetric met)
-    {
-        return widget->metric(met);
-    }
-};
-
 int ShivaVGWindowSurface::metric(PaintDeviceMetric met) const
 {
-    return QX11PaintEngine::metric(window(), met);
+    return qt_paint_device_metric(window(), met);
 }
 
 QT_END_NAMESPACE