Index

Package: Region

Description

package Cairo.Region is
Regions -- Representing a pixel-aligned area

Bindings to the Cairo 2D graphics library.

Regions are a simple graphical data type representing an area of integer- aligned rectangles. Thay are often used on raster surfaces to track areas of interest, such as change or clip areas.

Binding from C File version 1.10

Types

Cairo_Region 

type Cairo_Region is private;
A Cairo_Region represents a set of integer-aligned rectangles. It allows set-theoretical operations like Union and Intersect to be performed on them. Memory management of Cairo_Region is done with Reference and Destroy. Since: 1.10

Cairo_Rectangle_Int 

type Cairo_Rectangle_Int is record
      X, Y, Width, Height : aliased Gint;
   end record;

Cairo_Region_Overlap 

type Cairo_Region_Overlap is
     (Cairo_Region_Overlap_In,    --  Completely inside region
      Cairo_Region_Overlap_Out,   --  Completely outside region
      Cairo_Region_Overlap_Part   --  Partly inside region
     );

Constants & Global variables

Null_Region (Cairo_Region) 

Null_Region : constant Cairo_Region;

Subprograms & Entries

Create 

function Create return Cairo_Region;
Allocates a new empty region object. Returns: A newly allocated Cairo_Region. Free with Destroy. This function always returns a valid Cairo_Region; if memory cannot be allocated, then a special error object is returned where all operations on the object do nothing. You can check for this with Status.

Create_Rectangle 

function Create_Rectangle 
(Rectangle: access Cairo_Rectangle_Int) return Cairo_Region;
Allocates a new region object containing Rectangle. Returns: A newly allocated Cairo_Region. Free with Destroy. This function always returns a valid Cairo_Region; if memory cannot be allocated, then a special error object is returned where all operations on the object do nothing. You can check for this with Status.

Copy 

function Copy 
(Original: Cairo_Region) return Cairo_Region;
Allocates a new Cairo_Region object copying the area from Original. Returns: A newly allocated Cairo_Region. Free with Destroy. This function always returns a valid Cairo_Region; if memory cannot be allocated, then a special error object is returned where all operations on the object do nothing. You can check for this with Status.

Reference 

function Reference 
(Region: Cairo_Region) return Cairo_Region;
Increases the reference count on Region by one. This prefents Region from being destroyed until a matching call to Destroy is made.

Destroy 

procedure Destroy 
(Region: Cairo_Region);
Destroys a Cairo_Region object created with Create, Copy or Create_Rectangle.

= 

function "=" 
(A, B: Cairo_Region) return Boolean;
Compares whether A is equivalent to B. Null_Region as an argument is equal to itself, but not to any non-Null_Region region.

Status 

function Status 
(Region: Cairo_Region) return Cairo_Status;
Checks whether an error has occured for this region object. Returns: Cairo_Status_Success or Cairo_Status_No_Memory

Get_Extents 

procedure Get_Extents 
(Region: Cairo_Region;
Extents: out Cairo_Rectangle_Int);
Gets the bounding rectangle of Region as a Cairo_Rectangle_Int

Num_Rectangles 

function Num_Rectangles 
(Region: Cairo_Region) return Gint;
Returns the number of rectangle contained in Region

Get_Rectangle 

procedure Get_Rectangle 
(Region: Cairo_Region;
Nth: Gint;
Rectangle: out Cairo_Rectangle_Int);
Stores the Nth rectangle from the region in Rectangle.

Is_Empty 

function Is_Empty 
(Region: Cairo_Region) return Boolean;
Checks whether Region is empty.

Contains_Rectangle 

function Contains_Rectangle 
(Region: Cairo_Region;
Rectangle: access Cairo_Rectangle_Int) return Cairo_Region_Overlap;
Checks whether Rectangle is inside, outside or partially contained in Region

Contains_Point 

function Contains_Point 
(Region: Cairo_Region;
X: Gint;
Y: Gint) return Boolean;
Checks whether (X,Y) is contained in Region.

Translate 

procedure Translate 
(Region: Cairo_Region;
dX: Gint;
dY: Gint);
Translates Region by (dX,dY).

Subtract 

function Subtract 
(Dst: Cairo_Region;
Other: Cairo_Region) return Cairo_Status;
Subtracts Other from Dst and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Subtract_Rectangle 

function Subtract_Rectangle 
(Dst: Cairo_Region;
Rectangle: access Cairo_Rectangle_Int) return Cairo_Status;
Subtracts Rectangle from Dst and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Intersect 

function Intersect 
(Dst: Cairo_Region;
Other: Cairo_Region) return Cairo_Status;
Computes the intersection of Dst with Other and places the result in Dst Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Intersect_Rectangle 

function Intersect_Rectangle 
(Dst: Cairo_Region;
Rectangle: access Cairo_Rectangle_Int) return Cairo_Status;
Computes the intersection of Dst with Rectangle and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Union 

function Union 
(Dst: Cairo_Region;
Other: Cairo_Region) return Cairo_Status;
Computes the union of Dst with Other and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Union_Rectangle 

function Union_Rectangle 
(Dst: Cairo_Region;
Rectangle: access Cairo_Rectangle_Int) return Cairo_Status;
Computes the union of Dst with Rectangle and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Do_Xor 

function Do_Xor 
(Dst: Cairo_Region;
Other: Cairo_Region) return Cairo_Status;
Computes the exclusive difference of Dst with Other and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.

Xor_Rectangle 

function Xor_Rectangle 
(Dst: Cairo_Region;
Rectangle: access Cairo_Rectangle_Int) return Cairo_Status;
Computes the exclusive difference of Dst with Rectangle and places the result in Dst. Returns: Cairo_Status_Success or Cairo_Status_No_Memory.