Implement background color attribute for wxDataViewCtrl in wxOSX

Add support for this attribute for text-like cells to the native macOS
version too, to bring it up to parity with the generic and GTK ones.

Closes https://github.com/wxWidgets/wxWidgets/pull/1673

include/wx/osx/cocoa/dataview.h

@@ -142,6 +142,7 @@ public:
 
         [m_origFont release];
         [m_origTextColour release];
+        [m_origBackgroundColour release];
     }
 
     NSCell* GetColumnCell() const { return m_ColumnCell; }
@@ -186,6 +187,7 @@ public:
     // ones that do.
     NSFont *GetOriginalFont() const { return m_origFont; }
     NSColor *GetOriginalTextColour() const { return m_origTextColour; }
+    NSColor *GetOriginalBackgroundColour() const { return m_origBackgroundColour; }
 
     void SaveOriginalFont(NSFont *font)
     {
@@ -197,6 +199,11 @@ public:
         m_origTextColour = [textColour retain];
     }
 
+    void SaveOriginalBackgroundColour(NSColor *backgroundColour)
+    {
+        m_origBackgroundColour = [backgroundColour retain];
+    }
+
     // The ellipsization mode which we need to set for each cell being rendered.
     void SetEllipsizeMode(wxEllipsizeMode mode) { m_ellipsizeMode = mode; }
     wxEllipsizeMode GetEllipsizeMode() const { return m_ellipsizeMode; }
@@ -226,6 +233,7 @@ private:
     // we own those if they're non-NULL
     NSFont *m_origFont;
     NSColor *m_origTextColour;
+    NSColor *m_origBackgroundColour;
 
     wxEllipsizeMode m_ellipsizeMode;
 

interface/wx/dataview.h

@@ -713,10 +713,9 @@ public:
     /**
         Call this to set the background colour to use.
 
-        Currently this attribute is only supported in the generic version of
+        @since 2.9.4 - Generic
-        wxDataViewCtrl and ignored by the native GTK+ and OS X implementations.
+        @since 3.1.1 - wxGTK
-
+        @since 3.1.4 - wxOSX
-        @since 2.9.4
     */
     void SetBackgroundColour(const wxColour& colour);
 

src/osx/cocoa/dataview.mm

@@ -2720,6 +2720,7 @@ void wxDataViewRendererNativeData::Init()
 {
     m_origFont = NULL;
     m_origTextColour = NULL;
+    m_origBackgroundColour = NULL;
     m_ellipsizeMode = wxELLIPSIZE_MIDDLE;
     m_hasCustomFont = false;
 
@@ -2862,12 +2863,13 @@ void wxDataViewRenderer::SetAttr(const wxDataViewItemAttr& attr)
     wxDataViewRendererNativeData * const data = GetNativeData();
     NSCell * const cell = data->GetItemCell();
 
-    // set the font and text colour to use: we need to do it if we had ever
+    // set the font, background and text colour to use: we need to do it if we
-    // changed them before, even if this item itself doesn't have any special
+    // had ever changed them before, even if this item itself doesn't have any
-    // attributes as otherwise it would reuse the attributes from the previous
+    // special attributes as otherwise it would reuse the attributes from the
-    // cell rendered using the same renderer
+    // previous cell rendered using the same renderer
     NSFont *font = NULL;
     NSColor *colText = NULL;
+    NSColor *colBack = NULL;
 
     if ( attr.HasFont() )
     {
@@ -2892,34 +2894,67 @@ void wxDataViewRenderer::SetAttr(const wxDataViewItemAttr& attr)
         //else: can't change font if the cell doesn't have any
     }
 
-    if ( attr.HasColour() && [cell backgroundStyle] == NSBackgroundStyleLight )
+    // We don't apply the text or background colours if the cell is selected.
+    if ( [cell backgroundStyle] == NSBackgroundStyleLight )
     {
-        // we can set font for any cell but only NSTextFieldCell provides
+        if ( attr.HasColour() )
-        // a method for setting text colour so check that this method is
-        // available before using it
-        if ( [cell respondsToSelector:@selector(setTextColor:)] &&
-                [cell respondsToSelector:@selector(textColor)] )
         {
-            if ( !data->GetOriginalTextColour() )
+            // we can set font for any cell but only NSTextFieldCell provides
+            // a method for setting text colour so check that this method is
+            // available before using it
+            if ( [cell respondsToSelector:@selector(setTextColor:)] &&
+                    [cell respondsToSelector:@selector(textColor)] )
             {
-                // the cast to (untyped) id is safe because of the check above
+                if ( !data->GetOriginalTextColour() )
-                data->SaveOriginalTextColour([(id)cell textColor]);
+                {
-            }
+                    // the cast to (untyped) id is safe because of the check above
+                    data->SaveOriginalTextColour([(id)cell textColor]);
+                }
 
-            colText = attr.GetColour().OSXGetNSColor();
+                colText = attr.GetColour().OSXGetNSColor();
+            }
+        }
+
+        if ( attr.HasBackgroundColour() )
+        {
+            // Use the same logic as the text colour check above
+            if ( [cell respondsToSelector:@selector(setBackgroundColor:)] &&
+                    [cell respondsToSelector:@selector(backgroundColor)] )
+            {
+                if ( !data->GetOriginalBackgroundColour() )
+                    data->SaveOriginalTextColour([(id)cell backgroundColor]);
+
+                colBack = attr.GetBackgroundColour().OSXGetNSColor();
+            }
         }
     }
 
+
     if ( !font )
         font = data->GetOriginalFont();
     if ( !colText )
         colText = data->GetOriginalTextColour();
+    if ( !colBack )
+        colBack = data->GetOriginalBackgroundColour();
 
     if ( font )
         [cell setFont:font];
 
     if ( colText )
         [(id)cell setTextColor:colText];
+
+    if ( [cell respondsToSelector:@selector(setDrawsBackground:)] )
+    {
+        if ( colBack )
+        {
+            [(id)cell setDrawsBackground:true];
+            [(id)cell setBackgroundColor:colBack];
+        }
+        else
+        {
+            [(id)cell setDrawsBackground:false];
+        }
+    }
 }
 
 void wxDataViewRenderer::SetEnabled(bool enabled)