Cairo::Surface Class Reference

Inheritance diagram for Cairo::Surface:

Inheritance graph
[legend]

List of all members.


Detailed Description

A cairo surface represents an image, either as the destination of a drawing operation or as source when drawing onto another surface.

There are different subtypes of cairo surface for different drawing backends. This class is a base class for all subtypes and should not be used directly

Surfaces are reference-counted objects that should be used via Cairo::RefPtr.

Public Types

typedef cairo_surface_t cobject
 The underlying C cairo surface type.

Public Member Functions

const cobjectcobj () const
 Provides acces to the underlying C cairo surface.
cobjectcobj ()
 Provides acces to the underlying C cairo surface.
void copy_page ()
 Emits the current page for backends that support multiple pages, but doesn't clear it, so that the contents of the current page will be retained for the next page.
void finish ()
 This function finishes the surface and drops all references to external resources.
void flush ()
 Do any pending drawing for the surface and also restore any temporary modifications cairo has made to the surface's state.
void get_device_offset (double &x_offset, double &y_offset) const
 Returns a previous device offset set by set_device_offset().
void get_font_options (FontOptions &options) const
 Retrieves the default font rendering options for the surface.
SurfaceType get_type () const
void mark_dirty (int x, int y, int width, int height)
 Marks a rectangular area of the given surface dirty.
void mark_dirty ()
 Tells cairo to consider the data buffer dirty.
void set_device_offset (double x_offset, double y_offset)
 Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface.
void set_fallback_resolution (double x_pixels_per_inch, double y_pixels_per_inch)
 Sets the fallback resolution of the image in dots per inch.
void show_page ()
 Emits and clears the current page for backends that support multiple pages.
 Surface (cairo_surface_t *cobject, bool has_reference=false)
 Create a C++ wrapper for the C instance.
void write_to_png (cairo_write_func_t write_func, void *closure)
 Writes the Surface to the write function.
void write_to_png (const std::string &filename)
 Writes the contents of surface to a new file filename as a PNG image.
virtual ~Surface ()

Static Public Member Functions

static RefPtr< Surfacecreate (const RefPtr< Surface > other, Content content, int width, int height)
 Create a new surface that is as compatible as possible with an existing surface.

Protected Attributes

cobjectm_cobject
 The underlying C cairo surface type that is wrapped by this Surface.


Member Typedef Documentation

typedef cairo_surface_t Cairo::Surface::cobject

The underlying C cairo surface type.


Constructor & Destructor Documentation

Cairo::Surface::Surface ( cairo_surface_t *  cobject,
bool  has_reference = false 
) [explicit]

Create a C++ wrapper for the C instance.

This C++ instance should then be given to a RefPtr.

Parameters:
cobject The C instance.
has_reference Whether we already have a reference. Otherwise, the constructor will take an extra reference.

virtual Cairo::Surface::~Surface (  )  [virtual]


Member Function Documentation

const cobject* Cairo::Surface::cobj (  )  const [inline]

Provides acces to the underlying C cairo surface.

References m_cobject.

cobject* Cairo::Surface::cobj (  )  [inline]

Provides acces to the underlying C cairo surface.

References m_cobject.

void Cairo::Surface::copy_page (  ) 

Emits the current page for backends that support multiple pages, but doesn't clear it, so that the contents of the current page will be retained for the next page.

Use show_page() if you want to get an empty page after the emission.

Since:
1.6

static RefPtr<Surface> Cairo::Surface::create ( const RefPtr< Surface other,
Content  content,
int  width,
int  height 
) [static]

Create a new surface that is as compatible as possible with an existing surface.

The new surface will use the same backend as other unless that is not possible for some reason.

Parameters:
other an existing surface used to select the backend of the new surface
content the content for the new surface
width width of the new surface, (in device-space units)
height height of the new surface (in device-space units)
Returns:
a RefPtr to the newly allocated surface.

void Cairo::Surface::finish (  ) 

This function finishes the surface and drops all references to external resources.

For example, for the Xlib backend it means that cairo will no longer access the drawable, which can be freed. After calling finish() the only valid operations on a surface are getting and setting user data and referencing and destroying it. Further drawing to the surface will not affect the surface but will instead trigger a CAIRO_STATUS_SURFACE_FINISHED error.

When the Surface is destroyed, cairo will call finish() if it hasn't been called already, before freeing the resources associated with the Surface.

void Cairo::Surface::flush (  ) 

Do any pending drawing for the surface and also restore any temporary modifications cairo has made to the surface's state.

This function must be called before switching from drawing on the surface with cairo to drawing on it directly with native APIs. If the surface doesn't support direct access, then this function does nothing.

void Cairo::Surface::get_device_offset ( double &  x_offset,
double &  y_offset 
) const

Returns a previous device offset set by set_device_offset().

void Cairo::Surface::get_font_options ( FontOptions options  )  const

Retrieves the default font rendering options for the surface.

This allows display surfaces to report the correct subpixel order for rendering on them, print surfaces to disable hinting of metrics and so forth. The result can then be used with cairo_scaled_font_create().

Parameters:
options a FontOptions object into which to store the retrieved options. All existing values are overwritten

SurfaceType Cairo::Surface::get_type (  )  const

void Cairo::Surface::mark_dirty ( int  x,
int  y,
int  width,
int  height 
)

Marks a rectangular area of the given surface dirty.

Parameters:
x X coordinate of dirty rectangle
y Y coordinate of dirty rectangle
width width of dirty rectangle
height height of dirty rectangle

void Cairo::Surface::mark_dirty (  ) 

Tells cairo to consider the data buffer dirty.

In particular, if you've created an ImageSurface with a data buffer that you've allocated yourself and you draw to that data buffer using means other than cairo, you must call mark_dirty() before doing any additional drawing to that surface with cairo.

Note that if you do draw to the Surface outside of cairo, you must call flush() before doing the drawing.

void Cairo::Surface::set_device_offset ( double  x_offset,
double  y_offset 
)

Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface.

One use case for this function is when we want to create a Surface that redirects drawing for a portion of an onscreen surface to an offscreen surface in a way that is completely invisible to the user of the cairo API. Setting a transformation via cairo_translate() isn't sufficient to do this, since functions like Cairo::Context::device_to_user() will expose the hidden offset.

Note that the offset only affects drawing to the surface, not using the surface in a surface pattern.

Parameters:
x_offset the offset in the X direction, in device units
y_offset the offset in the Y direction, in device units

void Cairo::Surface::set_fallback_resolution ( double  x_pixels_per_inch,
double  y_pixels_per_inch 
)

Sets the fallback resolution of the image in dots per inch.

Parameters:
x_pixels_per_inch Pixels per inch in the x direction
y_pixels_per_inch Pixels per inch in the y direction

void Cairo::Surface::show_page (  ) 

Emits and clears the current page for backends that support multiple pages.

Use copy_page() if you don't want to clear the page.

Since:
1.6

void Cairo::Surface::write_to_png ( cairo_write_func_t  write_func,
void *  closure 
)

Writes the Surface to the write function.

Note:
For this function to be available, cairo must have been compiled with PNG support
Parameters:
write_func The function to be called when the backend needs to write data to an output stream
closure closure data for the write function

void Cairo::Surface::write_to_png ( const std::string &  filename  ) 

Writes the contents of surface to a new file filename as a PNG image.

Note:
For this function to be available, cairo must have been compiled with PNG support
Parameters:
filename the name of a file to write to


Member Data Documentation

The underlying C cairo surface type that is wrapped by this Surface.

Referenced by cobj().


The documentation for this class was generated from the following file:

Generated on Thu Sep 4 21:57:17 2008 for cairomm by  doxygen 1.5.5