add refreshRate to Screens. STUB but for XRandr!

the randr refreshrate is calculated from the current mode

autotests/mock_screens.cpp

@@ -37,6 +37,11 @@ QRect MockScreens::geometry(int screen) const
     return m_geometries.at(screen);
 }
 
+float MockScreens::refreshRate(int screen) const
+{
+    return 60.0f;
+}
+
 QSize MockScreens::size(int screen) const
 {
     return geometry(screen).size();

autotests/mock_screens.h

@@ -33,6 +33,7 @@ public:
     virtual ~MockScreens();
     QRect geometry(int screen) const override;
     int number(const QPoint &pos) const override;
+    float refreshRate(int screen) const override;
     QSize size(int screen) const override;
     void init() override;
 

screens.cpp

@@ -86,6 +86,18 @@ void Screens::init()
     m_currentFollowsMouse = settings.activeMouseScreen();
 }
 
+QString Screens::name(int screen) const
+{
+    qWarning("%s::name(int screen) is a stub, please reimplement it!", metaObject()->className());
+    return QLatin1String("DUMMY");
+}
+
+float Screens::refreshRate(int screen) const
+{
+    qWarning("%s::refreshRate(int screen) is a stub, please reimplement it!", metaObject()->className());
+    return 60.0f;
+}
+
 void Screens::reconfigure()
 {
     if (!m_config) {

screens.h

@@ -69,6 +69,10 @@ public:
      * @see geometryChanged()
      **/
     QRect geometry() const;
+    /**
+     * @returns current refreshrate of the @p screen.
+     **/
+    virtual float refreshRate(int screen) const;
     /**
      * @returns size of the @p screen.
      *

screens_xrandr.cpp

@@ -20,6 +20,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "screens_xrandr.h"
 #include "xcbutils.h"
 
+
 namespace KWin
 {
 
@@ -36,6 +37,7 @@ void XRandRScreens::update()
 {
     auto fallback = [this]() {
         m_geometries << QRect();
+        m_refreshRates << -1.0f;
         setCount(1);
     };
     m_geometries.clear();
@@ -45,16 +47,35 @@ void XRandRScreens::update()
         return;
     }
     xcb_randr_crtc_t *crtcs = resources.crtcs();
+    xcb_randr_mode_info_t *modes = resources.modes();
 
     QVector<Xcb::RandR::CrtcInfo> infos(resources->num_crtcs);
     for (int i = 0; i < resources->num_crtcs; ++i) {
         infos[i] = Xcb::RandR::CrtcInfo(crtcs[i], resources->config_timestamp);
     }
+
     for (int i = 0; i < resources->num_crtcs; ++i) {
+        float refreshRate = -1.0f;
         Xcb::RandR::CrtcInfo info(infos.at(i));
+        for (int j = 0; j < resources->num_modes; ++j) {
+            if (info->mode == modes[j].id) {
+                if (modes[j].htotal*modes[j].vtotal) { // BUG 313996
+                    // refresh rate calculation - WTF was wikipedia 1998 when I needed it?
+                    int dotclock = modes[j].dot_clock,
+                          vtotal = modes[j].vtotal;
+                    if (modes[j].mode_flags & XCB_RANDR_MODE_FLAG_INTERLACE)
+                        dotclock *= 2;
+                    if (modes[j].mode_flags & XCB_RANDR_MODE_FLAG_DOUBLE_SCAN)
+                        vtotal *= 2;
+                    refreshRate = dotclock/float(modes[j].htotal*vtotal);
+                }
+                break; // found mode
+            }
+        }
         const QRect geo = info.rect();
         if (geo.isValid()) {
             m_geometries << geo;
+            m_refreshRates << refreshRate;
         }
     }
     if (m_geometries.isEmpty()) {
@@ -103,6 +124,14 @@ int XRandRScreens::number(const QPoint &pos) const
     return bestScreen;
 }
 
+float XRandRScreens::refreshRate(int screen) const
+{
+    if (screen >= m_refreshRates.size() || screen < 0) {
+        return -1.0f;
+    }
+    return m_refreshRates.at(screen);
+}
+
 QSize XRandRScreens::size(int screen) const
 {
     const QRect geo = geometry(screen);

screens_xrandr.h

@@ -37,6 +37,7 @@ public:
     void init() override;
     QRect geometry(int screen) const override;
     int number(const QPoint& pos) const override;
+    float refreshRate(int screen) const override;
     QSize size(int screen) const override;
 
     using QObject::event;
@@ -49,6 +50,7 @@ private:
     template <typename T>
     void update();
     QVector<QRect> m_geometries;
+    QVector<float> m_refreshRates;
 };
 
 } // namespace