implement support for wxOR and wxCLEAR in wxCairoContext::SetLogicalFunction() (#9808)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54897 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/graphicc.cpp

@@ -356,6 +356,8 @@ public:
 
     virtual void * GetNativeContext();
 
+    virtual bool SetLogicalFunction( int function );
+
     virtual void StrokePath( const wxGraphicsPath& p );
     virtual void FillPath( const wxGraphicsPath& p , int fillStyle = wxWINDING_RULE );
 
@@ -1520,6 +1522,54 @@ void * wxCairoContext::GetNativeContext()
     return m_context;
 }
 
+// Cairo doesn't support bitwise logical function (a.k.a. ROP, raster output
+// mode). Cairo supports Porter-Duff compositing operators, but they are quite
+// different, although in some cases have similar names.
+bool wxCairoContext::SetLogicalFunction( int function )
+{
+    if (m_logicalFunction == function)
+        return true;
+
+    cairo_operator_t op;
+
+    switch ( function )
+    {
+        case wxCOPY:       // (default) src
+            op = CAIRO_OPERATOR_OVER; // (also default)
+            break;
+        case wxOR:         // src OR dst
+            op = CAIRO_OPERATOR_ADD;
+            break;
+        case wxNO_OP:      // dst
+            op = CAIRO_OPERATOR_DEST; // ignore the source
+            break;
+        case wxCLEAR:      // 0
+            op = CAIRO_OPERATOR_CLEAR;// clear dst
+            break;
+
+        case wxAND:        // src AND dst
+        case wxAND_INVERT: // (NOT src) AND dst
+        case wxAND_REVERSE:// src AND (NOT dst)
+        case wxEQUIV:      // (NOT src) XOR dst
+        case wxINVERT:     // NOT dst
+        case wxNAND:       // (NOT src) OR (NOT dst)
+        case wxNOR:        // (NOT src) AND (NOT dst)
+        case wxOR_INVERT:  // (NOT src) OR dst
+        case wxOR_REVERSE: // src OR (NOT dst)
+        case wxSET:        // 1
+        case wxSRC_INVERT: // NOT src
+        //wxXOR does _not_ correspond to CAIRO_OPERATOR_XOR
+        case wxXOR:        // src XOR dst
+        default:
+            return false;
+    }
+
+    m_logicalFunction = function;
+    cairo_set_operator(m_context, op);
+    return true;
+}
+
+
 //-----------------------------------------------------------------------------
 // wxCairoRenderer declaration
 //-----------------------------------------------------------------------------