Implemented wxCairoRenderer::CreateSubBitmap method.

interface/wx/graphics.h

@@ -446,9 +446,6 @@ public:
 
     /**
         Extracts a sub-bitmap from an existing bitmap.
-
-        Currently this function is implemented in the native MSW and OS X
-        versions but not when using Cairo.
      */
     virtual wxGraphicsBitmap CreateSubBitmap(const wxGraphicsBitmap& bitmap,
                                              wxDouble x, wxDouble y,

src/common/cairo.cpp

@@ -168,6 +168,8 @@
         (cairo_t *cr, double tx, double ty), (cr, tx, ty) ) \
     m( cairo_surface_flush, \
        (cairo_surface_t *surface), (surface) ) \
+    m( cairo_set_source_surface, \
+       (cairo_t *cr, cairo_surface_t *surface, double x, double y), (cr, surface, x, y) ) \
 
 #ifdef __WXMAC__
 #define wxCAIRO_PLATFORM_METHODS(m) \
@@ -230,6 +232,8 @@
        (cairo_surface_t *surface), (surface), -1) \
     m( const char *, cairo_version_string, \
        (), () , NULL ) \
+    m( cairo_surface_t*, cairo_surface_create_similar_image, \
+       (cairo_surface_t *other, cairo_format_t format, int width, int height), (other, format, width, height), NULL) \
     wxCAIRO_PLATFORM_METHODS(m)
 
 #define wxCAIRO_DECLARE_TYPE(rettype, name, args, argnames, defret) \

src/generic/graphicc.cpp

@@ -2787,15 +2787,41 @@ wxGraphicsBitmap wxCairoRenderer::CreateBitmapFromNativeBitmap( void* bitmap )
 }
 
 wxGraphicsBitmap
-wxCairoRenderer::CreateSubBitmap(const wxGraphicsBitmap& WXUNUSED(bitmap),
+wxCairoRenderer::CreateSubBitmap(const wxGraphicsBitmap& bitmap,
-                                 wxDouble WXUNUSED(x),
+                                 wxDouble x, wxDouble y,
-                                 wxDouble WXUNUSED(y),
+                                 wxDouble w, wxDouble h)
-                                 wxDouble WXUNUSED(w),
-                                 wxDouble WXUNUSED(h))
 {
-    wxGraphicsBitmap p;
+    ENSURE_LOADED_OR_RETURN(wxNullGraphicsBitmap);
-    wxFAIL_MSG("wxCairoRenderer::CreateSubBitmap is not implemented.");
+
-    return p;
+    wxCHECK_MSG(!bitmap.IsNull(), wxNullGraphicsBitmap, wxS("Invalid bitmap"));
+
+    wxCairoBitmapData* dataSrc = static_cast<wxCairoBitmapData*>(bitmap.GetRefData());
+    cairo_surface_t* srcSurface = dataSrc->GetCairoSurface();
+    int srcWidth = cairo_image_surface_get_width(srcSurface);
+    int srcHeight = cairo_image_surface_get_height(srcSurface);
+
+    int dstWidth = wxRound(w);
+    int dstHeight = wxRound(h);
+
+    wxCHECK_MSG( x >= 0.0 && y >= 0.0 && dstWidth > 0 && dstHeight > 0 &&
+                 x + dstWidth <= srcWidth && y + dstHeight <= srcHeight,
+                 wxNullGraphicsBitmap, wxS("Invalid bitmap region"));
+
+    cairo_surface_t* dstSurface = cairo_surface_create_similar_image(srcSurface,
+        cairo_image_surface_get_format(srcSurface),
+        dstWidth, dstHeight);
+
+    cairo_t* cr = cairo_create(dstSurface);
+    cairo_set_source_surface(cr, srcSurface, -x, -y);
+
+    cairo_rectangle(cr, 0.0, 0.0, dstWidth, dstHeight);
+    cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+    cairo_fill(cr);
+    cairo_destroy(cr);
+
+    wxGraphicsBitmap bmpRes;
+    bmpRes.SetRefData(new wxCairoBitmapData(this, dstSurface));
+    return bmpRes;
 }
 
 wxString wxCairoRenderer::GetName() const