kde5: add cairo surface to KDE5SalFrames

Change-Id: I0778ecffe5dbc5fdfe24705d37511e197a4a1ce4

vcl/Library_vclplug_kde5.mk

@@ -52,6 +52,7 @@ $(eval $(call gb_Library_use_libraries,vclplug_kde5,\
 
 $(eval $(call gb_Library_use_externals,vclplug_kde5,\
 	boost_headers \
+	cairo \
 	icuuc \
 	kde5 \
 	epoxy \

vcl/unx/kde5/KDE5SalFrame.cxx

@@ -340,6 +340,7 @@ void KDE5SalFrame::ReleaseGraphics( SalGraphics *pGraphics )
         if( m_aGraphics[i].pGraphics.get() == pGraphics )
         {
             m_aGraphics[i].bInUse = false;
+            cairo_surface_destroy( m_aGraphics[i].pSurface );
             break;
         }
     }
@@ -359,6 +360,7 @@ SalGraphics* KDE5SalFrame::AcquireGraphics()
 {
     if( GetWindow() )
     {
+        basegfx::B2IVector aSize( 142, 142 );
         for( int i = 0; i < nMaxGraphics; i++ )
         {
             if( ! m_aGraphics[i].bInUse )
@@ -367,6 +369,10 @@ SalGraphics* KDE5SalFrame::AcquireGraphics()
                 if( ! m_aGraphics[i].pGraphics )
                 {
                     m_aGraphics[i].pGraphics.reset( new KDE5SalGraphics( this, m_pWindow ) );
+
+                    //FIXME: those parameters are completely arbitrary, IDK what the right ones should be yet
+                    m_aGraphics[i].pSurface = cairo_image_surface_create( CAIRO_FORMAT_ARGB32, aSize.getX(), aSize.getY() );
+                    m_aGraphics[i].pGraphics->setSurface( m_aGraphics[i].pSurface, aSize );
                     //m_aGraphics[i].pGraphics->Init( this, GetWindow(), GetScreenNumber() );
                 }
                 return m_aGraphics[i].pGraphics.get();

vcl/unx/kde5/KDE5SalFrame.hxx

@@ -20,6 +20,7 @@
 #pragma once
 
 #include <memory>
+#include <cairo.h>
 
 #include <unx/saldisp.hxx>
 #include <unx/salframe.h>
@@ -39,8 +40,9 @@ class KDE5SalFrame : public SalFrame
         {
             std::unique_ptr<KDE5SalGraphics> pGraphics;
             bool bInUse;
+            cairo_surface_t* pSurface;
 
-            GraphicsHolder() : bInUse( false ) {}
+            GraphicsHolder() : bInUse( false ), pSurface(nullptr) {}
         };
 
         GraphicsHolder m_aGraphics[ nMaxGraphics ];