Points, Rectangles and Regions

GDK Reference Manual
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struct GdkPoint

struct GdkPoint
{
  gint16 x;
  gint16 y;
};

Defines the x and y coordinates of a point. Note that both are defined as gint16 values, so the coordinates are limited to between -32,768 and 32,767.

gint16 `x`	the x coordinate of the point.
gint16 `y`	the y coordinate of the point.

struct GdkRectangle

struct GdkRectangle
{
  gint16 x;
  gint16 y;
  guint16 width;
  guint16 height;
};

Defines the position and size of a rectangle.

gint16 `x`	the x coordinate of the left edge of the rectangle.
gint16 `y`	the y coordinate of the top of the rectangle.
guint16 `width`	the width of the rectangle.
guint16 `height`	the height of the rectangle.

gdk_rectangle_intersect ()

gint        gdk_rectangle_intersect         (GdkRectangle *src1,
                                             GdkRectangle *src2,
                                             GdkRectangle *dest);

Calculates the intersection of two rectangles.

`src1` :	a GdkRectangle.
`src2` :	a GdkRectangle.
`dest` :	the intersection of `src1` and `src2`.
Returns :	TRUE if the rectangles intersect.

gdk_rectangle_union ()

void        gdk_rectangle_union             (GdkRectangle *src1,
                                             GdkRectangle *src2,
                                             GdkRectangle *dest);

Calculates the union of two rectangles. The union of rectangles src1 and src2 is the smallest rectangle which includes both src1 and src2 within it.

`src1` :	a GdkRectangle.
`src2` :	a GdkRectangle.
`dest` :	the union of `src1` and `src2`.

struct GdkRegion

struct GdkRegion
{
  gpointer user_data;
};

A GdkRegion represents a set of pixels on the screen. The only user-visible field of the structure is the user_data member, which can be used to attach arbitrary data to the GdkRegion.

gpointer user_data arbitrary data attached to the GdkRegion.

gdk_region_new ()

GdkRegion*  gdk_region_new                  (void);

Creates a new empty GdkRegion.

Returns :

a new empty GdkRegion.

gdk_region_polygon ()

GdkRegion*  gdk_region_polygon              (GdkPoint *points,
                                             gint npoints,
                                             GdkFillRule fill_rule);

Creates a new GdkRegion using the polygon defined by a number of points.

`points` :	an array of GdkPoint structs.
`npoints` :	the number of elements in the `points` array.
`fill_rule` :	specifies which pixels are included in the region when the polygon overlaps itself.
Returns :	a new GdkRegion based on the given polygon.

enum GdkFillRule

typedef enum
{
  GDK_EVEN_ODD_RULE,
  GDK_WINDING_RULE
} GdkFillRule;

The method for determining which pixels are included in a region, when creating a GdkRegion from a polygon. The fill rule is only relevant for polygons which overlap themselves.

`GDK_EVEN_ODD_RULE`	areas which are overlapped an odd number of times are included in the region, while areas overlapped an even number of times are not.
`GDK_WINDING_RULE`	overlapping areas are always included.

gdk_region_destroy ()

void        gdk_region_destroy              (GdkRegion *region);

Destroys a GdkRegion.

region : a GdkRegion.

gdk_regions_intersect ()

GdkRegion*  gdk_regions_intersect           (GdkRegion *source1,
                                             GdkRegion *source2);

Returns the intersection of two regions.

`source1` :	a GdkRegion.
`source2` :	a GdkRegion.
Returns :	the intersection of `source1` and `source2`.

gdk_regions_union ()

GdkRegion*  gdk_regions_union               (GdkRegion *source1,
                                             GdkRegion *source2);

Returns the union of two regions. This is all pixels in either of source1 or source2.

`source1` :	a GdkRegion.
`source2` :	a GdkRegion.
Returns :	the union of `source1` and `source2`.

gdk_regions_subtract ()

GdkRegion*  gdk_regions_subtract            (GdkRegion *source1,
                                             GdkRegion *source2);

Subtracts one region from another. The result is a region containing all the pixels which are in source1, but which are not in source2.

`source1` :	a GdkRegion.
`source2` :	a GdkRegion to subtract from `source1`.
Returns :	`source1` - `source2`.

gdk_regions_xor ()

GdkRegion*  gdk_regions_xor                 (GdkRegion *source1,
                                             GdkRegion *source2);

Returns the difference between the union and the intersection of two regions. This is a region containing the pixels that are in one of the source regions, but which are not in both.

`source1` :	a GdkRegion.
`source2` :	a GdkRegion.
Returns :	the difference between the union and the intersection of `source1` and `source2`.

gdk_region_union_with_rect ()

GdkRegion*  gdk_region_union_with_rect      (GdkRegion *region,
                                             GdkRectangle *rect);

Returns the union of a region and a rectangle.

`region` :	a GdkRegion.
`rect` :	a GdkRectangle.
Returns :	the union of `region` and `rect`.

gdk_region_offset ()

void        gdk_region_offset               (GdkRegion *region,
                                             gint dx,
                                             gint dy);

Moves a region the specified distance.

`region` :	a GdkRegion.
`dx` :	the distance to move the region horizontally.
`dy` :	the distance to move the region vertically.

gdk_region_shrink ()

void        gdk_region_shrink               (GdkRegion *region,
                                             gint dx,
                                             gint dy);

Resizes a region by the specified amount. Positive values shrink the region. Negative values expand it.

`region` :	a GdkRegion.
`dx` :	the number of pixels to shrink the region horizontally.
`dy` :	the number of pixels to shrink the region vertically.

gdk_region_empty ()

gboolean    gdk_region_empty                (GdkRegion *region);

Returns TRUE if the GdkRegion is empty.

`region` :	a GdkRegion.
Returns :	TRUE if `region` is empty.

gdk_region_equal ()

gboolean    gdk_region_equal                (GdkRegion *region1,
                                             GdkRegion *region2);

Returns TRUE if the two regions are the same.

`region1` :	a GdkRegion.
`region2` :	a GdkRegion.
Returns :	TRUE if `region1` and `region2` are equal.

gdk_region_point_in ()

gboolean    gdk_region_point_in             (GdkRegion *region,
                                             int x,
                                             int y);

Returns TRUE if a point is in a region.

`region` :	a GdkRegion.
`x` :	the x coordinate of a point.
`y` :	the y coordinate of a point.
Returns :	TRUE if the point is in `region`.

gdk_region_rect_in ()

GdkOverlapType gdk_region_rect_in           (GdkRegion *region,
                                             GdkRectangle *rect);

Tests whether a rectangle is within a region.

`region` :	a GdkRegion.
`rect` :	a GdkRectangle.
Returns :	GDK_OVERLAP_RECTANGLE_IN, GDK_OVERLAP_RECTANGLE_OUT, or GDK_OVERLAP_RECTANGLE_PART, depending on whether the rectangle is inside, outside, or partly inside the GdkRegion, respectively.

enum GdkOverlapType

typedef enum
{
  GDK_OVERLAP_RECTANGLE_IN,
  GDK_OVERLAP_RECTANGLE_OUT,
  GDK_OVERLAP_RECTANGLE_PART
} GdkOverlapType;

Specifies the possible values returned by gdk_region_rect_in().

`GDK_OVERLAP_RECTANGLE_IN`	if the rectangle is inside the GdkRegion.
`GDK_OVERLAP_RECTANGLE_OUT`	if the rectangle is outside the GdkRegion.
`GDK_OVERLAP_RECTANGLE_PART`	if the rectangle is partly inside the GdkRegion.

gdk_region_get_clipbox ()

void        gdk_region_get_clipbox          (GdkRegion *region,
                                             GdkRectangle *rectangle);

Returns the smallest rectangle which includes the entire GdkRegion.

`region` :	a GdkRegion.
`rectangle` :	returns the smallest rectangle which includes all of `region`.