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

3 files changed, 7 insertions, 8 deletions

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