Make gridUnit available in the shell scripting

This makes it possible to set panel sizes based on the DPI and screen
size for example

shell/scripting/scriptengine.cpp

@@ -812,6 +812,7 @@ void ScriptEngine::setupEngine()
     m_scriptSelf.setProperty("applicationPath", newFunction(ScriptEngine::applicationPath));
     m_scriptSelf.setProperty("knownWallpaperPlugins", newFunction(ScriptEngine::knownWallpaperPlugins));
     m_scriptSelf.setProperty("ConfigFile", newFunction(ScriptEngine::configFile));
+    m_scriptSelf.setProperty("gridUnit", ScriptEngine::gridUnit());
 
     setGlobalObject(m_scriptSelf);
 }
@@ -845,6 +846,16 @@ QScriptValue ScriptEngine::desktops(QScriptContext *context, QScriptEngine *engi
     return containments;
 }
 
+QScriptValue ScriptEngine::gridUnit()
+{
+    int gridUnit = QFontMetrics(QGuiApplication::font()).boundingRect("M").height();
+    if (gridUnit % 2 != 0) {
+        gridUnit++;
+    }
+
+    return gridUnit;
+}
+
 Plasma::Corona *ScriptEngine::corona() const
 {
     return m_corona;

shell/scripting/scriptengine.h

@@ -23,6 +23,8 @@
 #include <QScriptEngine>
 #include <QScriptValue>
 
+#include <QFontMetrics>
+
 #include <kactivities/controller.h>
 
 #include "../shellcorona.h"
@@ -90,6 +92,7 @@ private:
     static QScriptValue userDataPath(QScriptContext *context, QScriptEngine *engine);
     static QScriptValue knownWallpaperPlugins(QScriptContext *context, QScriptEngine *engine);
     static QScriptValue configFile(QScriptContext *context, QScriptEngine *engine);
+    static QScriptValue gridUnit();
 
     // helpers
     static QScriptValue createContainment(const QString &type, const QString &defautPlugin,