An os_area is an association between a URL and a region within an image. This association causes the region to behave as a hyperlink. An os_area is not rendered on screen by browsers.

The region defined by an os_area can be a rectangle, circle, polygon, or the default area. The default area is the set of all points not mapped by an os_area . Coordinates that define the boundaries of a region are specified in pixels, relative to the upper left corner of the image. The shape of the region is specified by selecting the appropriate constructor, and can be modified through the rectangle() , circle() , polygon() , and default_area() member functions.

You can specify null-hyperlink behavior for an os_area by selecting the appropriate constructor or through the nohref() member function. In this case, rather than behaving as a hyperlink, no action is taken in the os_area when a user clicks within the region. Hyperlink behavior can be enabled through the href() member function.

os_area objects are collected within an os_image_map to define a client-side image map. The os_image_map is associated with an os_image through the os_image::usemap() member function.

Interface

Constructor

os_area( const string& href , int ul_x , int ul_y , int lr_x ,
int lr_y )

Constructs an area to associate the URL href with the rectangular region that has upper left corner ( ul_x , ul_y ) and lower right corner ( lr_x , lr_y ).

Constructor

os_area( int ul_x , int ul_y , int lr_x , int lr_y )

Constructs an area to associate no URL with the rectangular region that has upper left corner ( ul_x , ul_y) and lower right corner ( lr_x , lr_y ).

Constructor

os_area( const string& href , int c_x , int c_y ,_int radius )

Constructs an area to associate the URL href with the circular region that has center ( c_x , c_y) and radius radius .

Constructor

os_area( int c_x , int c_y ,_int radius )

Constructs an area to associate no URL with the circular region that has center ( c_x , c_y ) and radius radius .

Constructor

os_area( const string& href , const vector< pair< int, int > >& points )

Constructs an area to associate URL href with the polygon defined by the vector of points points . To complete the polygon, the last point is connected to the first point.

Constructor

os_area( const vector< pair< int, int > >& points )

Constructs an area to associate no URL with the polygon defined by the vector of points points . To close the polygon, the last point is connected to the first point.

Constructor

os_area( const string& href )

Constructs an area to associate the URL href with the default region, that is, the set of all points within the image not mapped by another area.

circle

os_area& circle( int c_x , int c_y ,_int radius )

Sets the region to be a circle with center ( c_x , c_y ) and radius radius , and returns a reference to the area.

clone

/* virtual */ os_element* clone() const

Returns a base class pointer to a heap-based deep copy of the area.

default_area

os_area& default_area()

Sets the region to be the set of all points within the image not mapped by another area, and returns a reference to the area.

href

string href() const

Returns the URL associated with the region. Returns the empty string if the region is not associated with a URL.

href

os_area& href( const string& url )

Associates URL url with the region and returns a reference to the area.

is_circle

bool is_circle( int& x , int& y , int& radius ) const

Returns true if the region is a circle; then sets ( x , y ) to the center of the circle and radius to the radius of the circle.

is_default_area

bool is_default_area() const

Returns true if the region represents the default region, that is, if it contains the set of all points within the image not mapped by another area.

is_nohref

bool is_nohref() const

Returns true if region is not associated with a URL.

is_polygon

bool is_polygon( vector< pair< int, int > >& points ) const

Returns true if the region is a polygon, and inserts an ( x , y ) pair into points for each point in the polygon.

is_rectangle

bool is_rectangle( int& ul_x , int& ul_y , int& lr_x , int& lr_y ) const

Returns true if the region is a rectangle; then sets ( ul_x , ul_y ) to the upper left corner of the rectangle, and ( lr_x , lr_y) to the lower right corner of the rectangle.

nohref

os_area& nohref()

Sets the region to be associated with no URL and returns a reference to the area.

polygon

os_area& polygon( const vector< pair< int, int > >& points )

Sets the region to be a polygon defined by the vector of points points and returns a reference to the area. To complete the polygon, the last point is connected to the first point.

print

/* virtual */ void print( ostream& os ) const

Prints the area to os .

rectangle

os_area& rectangle( int ul_x , int ul_y , int lr_x , int lr_y )

Sets the region to be a rectangle that has upper left corner ( ul_x , ul_y) and lower right corner ( lr_x , lr_y ), and returns a reference to the area.

os_area

Declaration

Interface