Related: rhbz#1373933 gtk3 emits a lot of style-updateds signals

so don't throw away font settings every time, check if the font settings
changed and only emit FontChanged if they differ from the last seen settings.

Change-Id: I129887e3e866f395da3b906a38cf568abea5de8e

4 files changed, 53 insertions, 3 deletions

diff --git a/vcl/inc/unx/gtk/gtkinst.hxx b/vcl/inc/unx/gtk/gtkinst.hxx
index 490cf698c2da..514b13f62580 100644
--- a/vcl/inc/unx/gtk/gtkinst.hxx
+++ b/vcl/inc/unx/gtk/gtkinst.hxx
@@ -242,6 +242,8 @@ public:
 #endif
 
     virtual const cairo_font_options_t* GetCairoFontOptions() override;
+            const cairo_font_options_t* GetLastSeenCairoFontOptions();
+                                   void ResetLastSeenCairoFontOptions();
 
     void                        RemoveTimer (SalTimer *pTimer);
 
@@ -254,6 +256,7 @@ private:
 #endif
     bool                        IsTimerExpired();
     bool                        bNeedsInit;
+    cairo_font_options_t*       m_pLastCairoFontOptions;
 
     mutable std::shared_ptr<vcl::unx::GtkPrintWrapper> m_xPrintWrapper;
 };
diff --git a/vcl/unx/gtk/gtkinst.cxx b/vcl/unx/gtk/gtkinst.cxx
index 0f624674e452..9a535f006734 100644
--- a/vcl/unx/gtk/gtkinst.cxx
+++ b/vcl/unx/gtk/gtkinst.cxx
@@ -155,6 +155,7 @@ GtkInstance::GtkInstance( SalYieldMutex* pMutex )
     : X11SalInstance( pMutex )
 #endif
     , bNeedsInit(true)
+    , m_pLastCairoFontOptions(nullptr)
 {
 }
 
@@ -200,6 +201,7 @@ GtkInstance::~GtkInstance()
     while( !m_aTimers.empty() )
         delete *m_aTimers.begin();
     DeInitAtkBridge();
+    ResetLastSeenCairoFontOptions();
 }
 
 SalFrame* GtkInstance::CreateFrame( SalFrame* pParent, SalFrameStyleFlags nStyle )
@@ -483,7 +485,24 @@ GtkInstance::getPrintWrapper() const
 
 const cairo_font_options_t* GtkInstance::GetCairoFontOptions()
 {
-    return gdk_screen_get_font_options(gdk_screen_get_default());
+    const cairo_font_options_t* pCairoFontOptions = gdk_screen_get_font_options(gdk_screen_get_default());
+    if (!m_pLastCairoFontOptions && pCairoFontOptions)
+        m_pLastCairoFontOptions = cairo_font_options_copy(pCairoFontOptions);
+    return pCairoFontOptions;
+}
+
+const cairo_font_options_t* GtkInstance::GetLastSeenCairoFontOptions()
+{
+    return m_pLastCairoFontOptions;
+}
+
+void GtkInstance::ResetLastSeenCairoFontOptions()
+{
+    if (m_pLastCairoFontOptions)
+    {
+        cairo_font_options_destroy(m_pLastCairoFontOptions);
+        m_pLastCairoFontOptions = nullptr;
+    }
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/unx/gtk/gtksalframe.cxx b/vcl/unx/gtk/gtksalframe.cxx
index 0d872cf9af86..9167a3f8c694 100644
--- a/vcl/unx/gtk/gtksalframe.cxx
+++ b/vcl/unx/gtk/gtksalframe.cxx
@@ -3235,7 +3235,21 @@ void GtkSalFrame::signalStyleSet( GtkWidget*, GtkStyle* pPrevious, gpointer fram
         // so post user event to safely dispatch the SalEvent::SettingsChanged
         // note: settings changed for multiple frames is avoided in winproc.cxx ImplHandleSettings
         GtkSalFrame::getDisplay()->SendInternalEvent( pThis, nullptr, SalEvent::SettingsChanged );
-        GtkSalFrame::getDisplay()->SendInternalEvent( pThis, nullptr, SalEvent::FontChanged );
+
+        // fire off font-changed when the system cairo font hints change
+        GtkInstance *pInstance = static_cast<GtkInstance*>(GetSalData()->m_pInstance);
+        const cairo_font_options_t* pLastCairoFontOptions = pInstance->GetLastSeenCairoFontOptions();
+        const cairo_font_options_t* pCurrentCairoFontOptions = gdk_screen_get_font_options(gdk_screen_get_default());
+        bool bFontSettingsChanged = true;
+        if (pLastCairoFontOptions && pCurrentCairoFontOptions)
+            bFontSettingsChanged = !cairo_font_options_equal(pLastCairoFontOptions, pCurrentCairoFontOptions);
+        else if (!pLastCairoFontOptions && !pCurrentCairoFontOptions)
+            bFontSettingsChanged = false;
+        if (bFontSettingsChanged)
+        {
+            pInstance->ResetLastSeenCairoFontOptions();
+            GtkSalFrame::getDisplay()->SendInternalEvent( pThis, nullptr, SalEvent::FontChanged );
+        }
     }
 
     /* #i64117# gtk sets a nice background pixmap
diff --git a/vcl/unx/gtk3/gtk3gtkframe.cxx b/vcl/unx/gtk3/gtk3gtkframe.cxx
index 49bce84eb9f4..3d3fc9e24105 100644
--- a/vcl/unx/gtk3/gtk3gtkframe.cxx
+++ b/vcl/unx/gtk3/gtk3gtkframe.cxx
@@ -3107,7 +3107,21 @@ void GtkSalFrame::signalStyleUpdated(GtkWidget*, gpointer frame)
 
     // note: settings changed for multiple frames is avoided in winproc.cxx ImplHandleSettings
     GtkSalFrame::getDisplay()->SendInternalEvent( pThis, nullptr, SalEvent::SettingsChanged );
-    GtkSalFrame::getDisplay()->SendInternalEvent( pThis, nullptr, SalEvent::FontChanged );
+
+    // fire off font-changed when the system cairo font hints change
+    GtkInstance *pInstance = static_cast<GtkInstance*>(GetSalData()->m_pInstance);
+    const cairo_font_options_t* pLastCairoFontOptions = pInstance->GetLastSeenCairoFontOptions();
+    const cairo_font_options_t* pCurrentCairoFontOptions = gdk_screen_get_font_options(gdk_screen_get_default());
+    bool bFontSettingsChanged = true;
+    if (pLastCairoFontOptions && pCurrentCairoFontOptions)
+        bFontSettingsChanged = !cairo_font_options_equal(pLastCairoFontOptions, pCurrentCairoFontOptions);
+    else if (!pLastCairoFontOptions && !pCurrentCairoFontOptions)
+        bFontSettingsChanged = false;
+    if (bFontSettingsChanged)
+    {
+        pInstance->ResetLastSeenCairoFontOptions();
+        GtkSalFrame::getDisplay()->SendInternalEvent( pThis, nullptr, SalEvent::FontChanged );
+    }
 }
 
 gboolean GtkSalFrame::signalWindowState( GtkWidget*, GdkEvent* pEvent, gpointer frame )