Implemented wxBitmap::HasAlpha() and ::UseAlpha().

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@32086 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/bitmap.tex

@@ -3,7 +3,7 @@
 %\overview{Overview}{wxbitmapoverview}
 %
 This class encapsulates the concept of a platform-dependent bitmap,
-either monochrome or colour.
+either monochrome or colour or colour with alpha channel support.
 
 \wxheading{Derived from}
 
@@ -72,7 +72,8 @@ bitmaps from static data.
 
 Creates a new bitmap. A depth of -1 indicates the depth of the current screen
 or visual. Some platforms only support 1 for monochrome and -1 for the current
-colour setting.
+colour setting. Beginning with version 2.5.4 of wxWidgets a depth if 32 including
+an alpha channel is supported under MSW, Mac and GTK+.
 
 \func{}{wxBitmap}{\param{const char**}{ bits}}
 

include/wx/gtk/bitmap.h

@@ -137,8 +137,8 @@ public:
     void *GetRawData(wxPixelDataBase& data, int bpp);
     void UngetRawData(wxPixelDataBase& data);
 
-    bool HasAlpha() const { return true; }
-    void UseAlpha() { }
+    bool HasAlpha() const;
+    void UseAlpha();
 
 protected:
     bool CreateFromXpm(const char **bits);

include/wx/gtk1/bitmap.h

@@ -137,8 +137,8 @@ public:
     void *GetRawData(wxPixelDataBase& data, int bpp);
     void UngetRawData(wxPixelDataBase& data);
 
-    bool HasAlpha() const { return true; }
-    void UseAlpha() { }
+    bool HasAlpha() const;
+    void UseAlpha();
 
 protected:
     bool CreateFromXpm(const char **bits);

src/gtk/bitmap.cpp

@@ -1597,6 +1597,23 @@ void wxBitmap::UngetRawData(wxPixelDataBase& data)
 {
 }
 
+
+bool wxBitmap::HasAlpha() const 
+{
+#ifdef __WXGTK20__
+    return HasPixbuf();
+#else
+    return false;
+#endif
+}
+
+void wxBitmap::UseAlpha()
+{ 
+#ifdef __WXGTK20__
+    GetPixbuf();
+#endif
+}
+
 //-----------------------------------------------------------------------------
 // wxBitmapHandler
 //-----------------------------------------------------------------------------

src/gtk1/bitmap.cpp

@@ -1597,6 +1597,23 @@ void wxBitmap::UngetRawData(wxPixelDataBase& data)
 {
 }
 
+
+bool wxBitmap::HasAlpha() const 
+{
+#ifdef __WXGTK20__
+    return HasPixbuf();
+#else
+    return false;
+#endif
+}
+
+void wxBitmap::UseAlpha()
+{ 
+#ifdef __WXGTK20__
+    GetPixbuf();
+#endif
+}
+
 //-----------------------------------------------------------------------------
 // wxBitmapHandler
 //-----------------------------------------------------------------------------