QStyleHelper: Base DPI-calculation on QScreen.

- Use qt_defaultDpiX() to obtain the resolution, which
  obtains it from QScreen. This implies that for X11,
  which previously used a hardcoded default of 96 DPI,
  the real resolution will be used (typically 75).

- Since many tests (layouts, graphicsview) contain
  test data for 96 DPI, add an attribute to
  QCoreApplication making it possible to set the
  resolution to 96 DPI for testing.

Change-Id: I77c8233a96b0d75de07406f58d48886a89c3de06
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

1 files changed, 14 insertions, 18 deletions

diff --git a/src/gui/text/qfont.cpp b/src/gui/text/qfont.cpp
index 5bf9094615..1ac398967d 100644
--- a/src/gui/text/qfont.cpp
+++ b/src/gui/text/qfont.cpp
@@ -138,36 +138,32 @@ extern bool qt_is_gui_used;
 
 Q_GUI_EXPORT int qt_defaultDpiX()
 {
+    if (qApp->testAttribute(Qt::AA_Use96Dpi))
+        return 96;
+
     if (!qt_is_gui_used)
         return 75;
 
-    int dpi;
-    QScreen *screen = QGuiApplication::primaryScreen();
-    if (screen) {
-        dpi = qRound(screen->logicalDotsPerInchX());
-    } else {
-        //PI has not been initialised, or it is being initialised. Give a default dpi
-        dpi = 100;
-    }
+    if (const QScreen *screen = QGuiApplication::primaryScreen())
+        return qRound(screen->logicalDotsPerInchX());
 
-    return dpi;
+    //PI has not been initialised, or it is being initialised. Give a default dpi
+    return 100;
 }
 
 Q_GUI_EXPORT int qt_defaultDpiY()
 {
+    if (qApp->testAttribute(Qt::AA_Use96Dpi))
+        return 96;
+
     if (!qt_is_gui_used)
         return 75;
 
-    int dpi;
-    QScreen *screen = QGuiApplication::primaryScreen();
-    if (screen) {
-        dpi = qRound(screen->logicalDotsPerInchY());
-    } else {
-        //PI has not been initialised, or it is being initialised. Give a default dpi
-        dpi = 100;
-    }
+    if (const QScreen *screen = QGuiApplication::primaryScreen())
+        return qRound(screen->logicalDotsPerInchY());
 
-    return dpi;
+    //PI has not been initialised, or it is being initialised. Give a default dpi
+    return 100;
 }
 
 Q_GUI_EXPORT int qt_defaultDpi()