ipicture_painter

The ipicture_painter implements the COM IPicture-Interface which allows loading bmp, jpg and gif image files. The class draws the image on a background_wnd. If the drawing-rectangle of the painter is smaller than the image the image will be clipped. Copying an ipicture is a non-expensive operation - it's just a call to AddRef()!

namespace win32 { namespace gui {

     namespace detail {

          // base of the ipicture_painters. note how the exception is specified for the Derived class ;-)
          template <class Derived>
          struct ipicture_painter_base : painter_base
          {    
               typedef ipicture_painter_base_impl::param0 param0;

               // exceptions
               typedef bg_wnd::general_exception<Derived, 0> file_not_found;
               
               void load_file(const std::string& file_name);
               const bg_wnd::ipicture& get_ipicture() const;
          };

     }    // namespace detail

     // ========================================================================================================= //

     class ipicture_painter : public detail::ipicture_painter_base<ipicture_painter>
     {
     public:
          // c'tor
          ipicture_painter(const std::string& file_name = "");             

          // virtual functions of painter_base
          ipicture_painter* clone() const;
          void draw(HDC hDC, int cx, int cy);     
     };

} }  // namespace win32::gui

Note:

• get_ipicture() returns a const reference to the bg_wnd::ipicture-object on which this painter is based
  
  

• If the filename passed to load_file() or the c'tor doesn't exist an ipicture_painter::file_not_found-exception is thrown (but note an empty string will not throw)
  
  

• ipicture_painter is derived from ipicture_painter_base which implements the loading and drawing of the ipicture. tile_ipicture_base is also derived from this class. ipicture_painter_base is a template to achieve different exception-classes. With this in mind you can separate between exceptions of the two classes because they're distinct:

  try {
       add_painter<ipicture_painter> ("c:\pic1.gif");
       add_painter<tile_ipicture_painter> ("c:\pic2.gif");
  }
  catch (ipicture_painter::file_not_found&) {
       // first line has thrown. react in an appropiate manner
       ...
  }
  catch (tile_ipicture_painter::file_not_found&) {
       // second line has thrown. react in an appropiate manner
       ...
  }
  

Example:

add_painter<ipicture_painter> ("c:\\img1.jpg");

The result is as follows

tile_ipicture_painter

The tile_ipicture_painter does the same as the ipicture_painter with the difference that the image loaded from the file will be displayed in tiles. You can optionally set the size of the tiles.

namespace win32 { namespace gui {

     class tile_ipicture_painter : public detail::ipicture_painter_base<tile_ipicture_painter>
     {
     public:
          typedef SIZE param1;

          // c'tor
          tile_ipicture_painter(const std::string& file_name = "");             
          tile_ipicture_painter(const std::string& file_name, SIZE tile_size);
          
          // virtual functions of painter_base
          tile_ipicture_painter* clone() const;   
          void draw(HDC hDC, int cx, int cy);          

          // own functions
          void tile_size(SIZE tile_size);
          SIZE tile_size() const;
     };

} }  // namespace win32::gui

Note:

• The same as for ipicture_painter applies to this class
  
  

• tile_size() sets and returns the current tile size. If the image is larger it will be clipped. By default the tile size is cx = 0, cy = 0 which means the painter shall determine the size of the image and use that size

Example:

const SIZE tile_size = ...;
add_painter<tile_ipicture_painter> ("c:\\img1.jpg", tile_size);

The result is as follows

tile_size = { 100, 100 }	tile_size = { 0, 0 } (determine resource size)