Adding IsSolid to wxColour

Under macOS colors can be patterns, then accessors for RGB values are useless, IsSolid returns true if the color can be expressed in RGB values at all.

include/wx/colour.h

@@ -119,6 +119,9 @@ public:
     virtual ChannelType Alpha() const
         { return wxALPHA_OPAQUE ; }
     
+    virtual bool IsSolid() const
+        { return true; }
+
     // implemented in colourcmn.cpp
     virtual wxString GetAsString(long flags = wxC2S_NAME | wxC2S_CSS_SYNTAX) const;
 

include/wx/osx/core/colour.h

@@ -34,6 +34,8 @@ public:
     virtual ChannelType Blue() const wxOVERRIDE;
     virtual ChannelType Alpha() const wxOVERRIDE;
 
+    virtual bool IsSolid() const wxOVERRIDE;
+
     wxColour& operator=(const wxColour& col);
 
     // comparison
@@ -91,6 +93,9 @@ public:
     virtual CGFloat Blue() const = 0;
     virtual CGFloat Alpha() const = 0;
  
+    virtual bool IsSolid() const
+        { return true; }
+
     virtual CGColorRef GetCGColor() const = 0;
     
     virtual wxColourRefData* Clone() const = 0;

interface/wx/colour.h

@@ -182,6 +182,11 @@ public:
     */
     virtual unsigned char Red() const;
 
+    /**
+        Returns @true if the color can be described using RGB values, ie is solid,
+        @false if it is a pattern (currently only possible on macOS)
+    */
+    virtual bool IsSolid() const;
     //@{
     /**
         Sets the RGB intensity values using the given values (first overload),

src/osx/cocoa/colour.mm

@@ -27,6 +27,8 @@ public:
     virtual CGFloat Blue() const wxOVERRIDE;
     virtual CGFloat Alpha() const wxOVERRIDE;
     
+    virtual bool IsSolid() const wxOVERRIDE;
+
     CGColorRef GetCGColor() const wxOVERRIDE;
     
     virtual wxColourRefData* Clone() const wxOVERRIDE { return new wxNSColorRefData(*this); }
@@ -94,6 +96,11 @@ CGFloat wxNSColorRefData::Alpha() const
     return 0.0;
 }
 
+bool wxNSColorRefData::IsSolid() const
+{
+    return [m_nsColour colorUsingColorSpaceName:NSCalibratedRGBColorSpace] != nil;
+}
+
 CGColorRef wxNSColorRefData::GetCGColor() const
 {
 #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_8

src/osx/core/colour.cpp

@@ -189,6 +189,13 @@ wxColour::ChannelType wxColour::Alpha() const
     return wxRound(M_COLDATA->Alpha() * 255.0);
 }
 
+bool wxColour::IsSolid() const
+{
+    wxCHECK_MSG( IsOk(), false, "invalid colour" );
+
+    return M_COLDATA->IsSolid();
+}
+
 #if wxOSX_USE_COCOA_OR_CARBON
 void wxColour::GetRGBColor(RGBColor* col) const
 {