Add API to create wxGraphicsContext from win32 HDC

Add wxGraphicsContext::CreateFromNativeHDC() and wxGraphicsRenderer::
CreateContextFromNativeHDC() to allow creation not only from native
renderer object, but also from HDC, which is something universally
supported by win32 implementations.

include/wx/graphics.h

@@ -445,6 +445,10 @@ public:
 
     static wxGraphicsContext* CreateFromNativeWindow( void * window );
 
+#ifdef __WXMSW__
+    static wxGraphicsContext* CreateFromNativeHDC(WXHDC dc);
+#endif
+
     static wxGraphicsContext* Create( wxWindow* window );
 
 #if wxUSE_IMAGE
@@ -830,6 +834,10 @@ public:
 
     virtual wxGraphicsContext * CreateContextFromNativeWindow( void * window ) = 0;
 
+#ifdef __WXMSW__
+    virtual wxGraphicsContext * CreateContextFromNativeHDC(WXHDC dc) = 0;
+#endif
+
     virtual wxGraphicsContext * CreateContext( wxWindow* window ) = 0;
 
 #if wxUSE_IMAGE

interface/wx/graphics.h

@@ -482,6 +482,15 @@ public:
     */
     static wxGraphicsContext* CreateFromNativeWindow(void* window);
 
+    /**
+        Creates a wxGraphicsContext from a native DC handle. Windows only.
+
+        @see wxGraphicsRenderer::CreateContextFromNativeHDC()
+
+        @since 3.1.1
+    */
+    static wxGraphicsContext* CreateFromNativeHDC(WXHDC dc);
+
     /**
        Create a lightweight context that can be used only for measuring text.
     */
@@ -1321,6 +1330,13 @@ public:
     */
     virtual wxGraphicsContext* CreateContextFromNativeWindow(void* window) = 0;
 
+    /**
+        Creates a wxGraphicsContext from a native DC handle. Windows only.
+
+        @since 3.1.1
+    */
+    static wxGraphicsContext* CreateContextFromNativeHDC(WXHDC dc);
+
     /**
         Creates a wxGraphicsContext that can be used for measuring texts only.
         No drawing commands are allowed.

src/common/graphcmn.cpp

@@ -961,6 +961,13 @@ wxGraphicsContext* wxGraphicsContext::CreateFromNativeWindow( void * window )
     return wxGraphicsRenderer::GetDefaultRenderer()->CreateContextFromNativeWindow(window);
 }
 
+#ifdef __WXMSW__
+wxGraphicsContext* wxGraphicsContext::CreateFromNativeHDC(WXHDC dc)
+{
+    return wxGraphicsRenderer::GetDefaultRenderer()->CreateContextFromNativeHDC(dc);
+}
+#endif
+
 wxGraphicsContext* wxGraphicsContext::Create( wxWindow* window )
 {
     return wxGraphicsRenderer::GetDefaultRenderer()->CreateContext(window);

src/generic/graphicc.cpp

@@ -2823,6 +2823,11 @@ public :
     virtual wxGraphicsContext * CreateContextFromNativeContext( void * context ) wxOVERRIDE;
 
     virtual wxGraphicsContext * CreateContextFromNativeWindow( void * window ) wxOVERRIDE;
+
+#ifdef __WXMSW__
+    virtual wxGraphicsContext * CreateContextFromNativeHDC(WXHDC dc) wxOVERRIDE;
+#endif
+
 #if wxUSE_IMAGE
     virtual wxGraphicsContext * CreateContextFromImage(wxImage& image) wxOVERRIDE;
 #endif // wxUSE_IMAGE
@@ -2961,6 +2966,14 @@ wxGraphicsContext * wxCairoRenderer::CreateContextFromNativeWindow( void * windo
 #endif
 }
 
+#ifdef __WXMSW__
+wxGraphicsContext * wxCairoRenderer::CreateContextFromNativeHDC(WXHDC dc)
+{
+    ENSURE_LOADED_OR_RETURN(NULL);
+    return new wxCairoContext(this, (HDC)dc);
+}
+#endif
+
 #if wxUSE_IMAGE
 wxGraphicsContext * wxCairoRenderer::CreateContextFromImage(wxImage& image)
 {

src/msw/graphics.cpp

@@ -553,6 +553,8 @@ public :
 
     virtual wxGraphicsContext * CreateContextFromNativeWindow( void * window ) wxOVERRIDE;
 
+    virtual wxGraphicsContext * CreateContextFromNativeHDC(WXHDC dc) wxOVERRIDE;
+
     virtual wxGraphicsContext * CreateContext( wxWindow* window ) wxOVERRIDE;
 
 #if wxUSE_IMAGE
@@ -2409,6 +2411,12 @@ wxGraphicsContext * wxGDIPlusRenderer::CreateContextFromNativeWindow( void * win
     return new wxGDIPlusContext(this,(HWND) window);
 }
 
+wxGraphicsContext * wxGDIPlusRenderer::CreateContextFromNativeHDC(WXHDC dc)
+{
+    ENSURE_LOADED_OR_RETURN(NULL);
+    return new wxGDIPlusContext(this, new Graphics((HDC)dc));
+}
+
 wxGraphicsContext * wxGDIPlusRenderer::CreateContext( wxWindow* window )
 {
     ENSURE_LOADED_OR_RETURN(NULL);

src/msw/graphicsd2d.cpp

@@ -4346,6 +4346,8 @@ public :
 
     wxGraphicsContext* CreateContextFromNativeWindow(void* window) wxOVERRIDE;
 
+    wxGraphicsContext * CreateContextFromNativeHDC(WXHDC dc) wxOVERRIDE;
+
     wxGraphicsContext* CreateContext(wxWindow* window) wxOVERRIDE;
 
 #if wxUSE_IMAGE
@@ -4486,6 +4488,11 @@ wxGraphicsContext* wxD2DRenderer::CreateContextFromNativeWindow(void* window)
     return new wxD2DContext(this, m_direct2dFactory, (HWND)window);
 }
 
+wxGraphicsContext* wxD2DRenderer::CreateContextFromNativeHDC(WXHDC dc)
+{
+    return new wxD2DContext(this, m_direct2dFactory, (HDC)dc, wxSize(0, 0));
+}
+
 wxGraphicsContext* wxD2DRenderer::CreateContext(wxWindow* window)
 {
     return new wxD2DContext(this, m_direct2dFactory, (HWND)window->GetHWND());