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GDK Reference Manual | |
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#include <gdk/gdk.h>
GdkPoint;
GdkRectangle;
gboolean gdk_rectangle_intersect (GdkRectangle *src1,
GdkRectangle *src2,
GdkRectangle *dest);
void gdk_rectangle_union (GdkRectangle *src1,
GdkRectangle *src2,
GdkRectangle *dest);
GdkRegion;
GdkRegion* gdk_region_new (void);
GdkRegion* gdk_region_polygon (GdkPoint *points,
gint npoints,
GdkFillRule fill_rule);
enum GdkFillRule;
GdkRegion* gdk_region_copy (GdkRegion *region);
GdkRegion* gdk_region_rectangle (GdkRectangle *rectangle);
void gdk_region_destroy (GdkRegion *region);
void gdk_region_get_clipbox (GdkRegion *region,
GdkRectangle *rectangle);
void gdk_region_get_rectangles (GdkRegion *region,
GdkRectangle **rectangles,
gint *n_rectangles);
gboolean gdk_region_empty (GdkRegion *region);
gboolean gdk_region_equal (GdkRegion *region1,
GdkRegion *region2);
gboolean gdk_region_point_in (GdkRegion *region,
int x,
int y);
GdkOverlapType gdk_region_rect_in (GdkRegion *region,
GdkRectangle *rectangle);
enum GdkOverlapType;
void gdk_region_offset (GdkRegion *region,
gint dx,
gint dy);
void gdk_region_shrink (GdkRegion *region,
gint dx,
gint dy);
void gdk_region_union_with_rect (GdkRegion *region,
GdkRectangle *rect);
void gdk_region_intersect (GdkRegion *source1,
GdkRegion *source2);
void gdk_region_union (GdkRegion *source1,
GdkRegion *source2);
void gdk_region_subtract (GdkRegion *source1,
GdkRegion *source2);
void gdk_region_xor (GdkRegion *source1,
GdkRegion *source2);
GdkSpan;
void (*GdkSpanFunc) (GdkSpan *span,
gpointer data);
void gdk_region_spans_intersect_foreach (GdkRegion *region,
GdkSpan *spans,
int n_spans,
gboolean sorted,
GdkSpanFunc function,
gpointer data);
GDK provides the GdkPoint, GdkRectangle, GdkRegion and GdkSpan data types for representing pixels and sets of pixels on the screen.
GdkPoint is a simple structure containing an x and y coordinate of a point.
GdkRectangle is a structure holding the position and size of a rectangle.
The intersection of two rectangles can be computed with
gdk_rectangle_intersect(). To find the union of two rectangles use
gdk_rectangle_union().
GdkRegion is an opaque data type holding a set of arbitrary pixels, and is
usually used for clipping graphical operations (see gdk_gc_set_clip_region()).
GdkSpan is a structure holding a spanline. A spanline is a horizontal line that
is one pixel wide. It is mainly used when rasterizing other graphics primitives.
It can be intersected to regions by using gdk_region_spans_intersect_foreach().
typedef struct {
gint x;
gint y;
} GdkPoint;
Defines the x and y coordinates of a point.
gint x; |
the x coordinate of the point. |
gint y; |
the y coordinate of the point. |
typedef struct {
gint x;
gint y;
gint width;
gint height;
} GdkRectangle;
Defines the position and size of a rectangle.
gint x; |
the x coordinate of the left edge of the rectangle. |
gint y; |
the y coordinate of the top of the rectangle. |
gint width; |
the width of the rectangle. |
gint height; |
the height of the rectangle. |
gboolean gdk_rectangle_intersect (GdkRectangle *src1, GdkRectangle *src2, GdkRectangle *dest);
Calculates the intersection of two rectangles.
It is allowed for dest to be the same as either src1 or src2.
src1 : |
a GdkRectangle |
src2 : |
a GdkRectangle |
dest : |
return location for the intersection of src1 and src2
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| Returns : | TRUE if the rectangles intersect.
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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.
It is allowed for dest to be the same as either src1 or src2.
src1 : |
a GdkRectangle |
src2 : |
a GdkRectangle |
dest : |
return location for the union of src1 and src2
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typedef struct _GdkRegion GdkRegion;
A GdkRegion represents a set of pixels on the screen.
GdkRegion* gdk_region_new (void);
Creates a new empty GdkRegion.
| Returns : | a new empty GdkRegion |
GdkRegion* gdk_region_polygon (GdkPoint *points, gint npoints, GdkFillRule fill_rule);
Creates a new GdkRegion using the polygon defined by a number of points.
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.
GdkRegion* gdk_region_copy (GdkRegion *region);
Copies region, creating an identical new region.
region : |
a GdkRegion |
| Returns : | a new region identical to region
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GdkRegion* gdk_region_rectangle (GdkRectangle *rectangle);
Creates a new region containing the area rectangle.
rectangle : |
a GdkRectangle |
| Returns : | a new region |
void gdk_region_destroy (GdkRegion *region);
Destroys a GdkRegion.
region : |
a GdkRegion |
void gdk_region_get_clipbox (GdkRegion *region, GdkRectangle *rectangle);
Obtains the smallest rectangle which includes the entire GdkRegion.
region : |
a GdkRegion |
rectangle : |
return location for the clipbox |
void gdk_region_get_rectangles (GdkRegion *region, GdkRectangle **rectangles, gint *n_rectangles);
Obtains the area covered by the region as a list of rectangles.
The array returned in rectangles must be freed with g_free().
region : |
a GdkRegion |
rectangles : |
return location for an array of rectangles |
n_rectangles : |
length of returned array |
gboolean gdk_region_empty (GdkRegion *region);
Finds out if the GdkRegion is empty.
region : |
a GdkRegion |
| Returns : | TRUE if region is empty.
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gboolean gdk_region_equal (GdkRegion *region1, GdkRegion *region2);
Finds out if the two regions are the same.
gboolean gdk_region_point_in (GdkRegion *region, int x, int y);
Finds out 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.
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GdkOverlapType gdk_region_rect_in (GdkRegion *region, GdkRectangle *rectangle);
Tests whether a rectangle is within a region.
region : |
a GdkRegion. |
rectangle : |
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.
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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().
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 |
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 |
void gdk_region_union_with_rect (GdkRegion *region, GdkRectangle *rect);
Sets the area of region to the union of the areas of region and
rect. The resulting area is the set of pixels contained in
either region or rect.
region : |
a GdkRegion. |
rect : |
a GdkRectangle. |
void gdk_region_intersect (GdkRegion *source1, GdkRegion *source2);
Sets the area of source1 to the intersection of the areas of source1
and source2. The resulting area is the set of pixels contained in
both source1 and source2.
void gdk_region_union (GdkRegion *source1, GdkRegion *source2);
Sets the area of source1 to the union of the areas of source1 and
source2. The resulting area is the set of pixels contained in
either source1 or source2.
void gdk_region_subtract (GdkRegion *source1, GdkRegion *source2);
Subtracts the area of source2 from the area source1. The resulting
area is the set of pixels contained in source1 but not in source2.
void gdk_region_xor (GdkRegion *source1, GdkRegion *source2);
Sets the area of source1 to the exclusive-OR of the areas of source1
and source2. The resulting area is the set of pixels contained in one
or the other of the two sources but not in both.
typedef struct {
gint x;
gint y;
gint width;
} GdkSpan;
A GdkSpan represents a horizontal line of pixels starting
at the pixel with coordinates x, y and ending before x + width, y.
gint x; |
x coordinate of the first pixel. |
gint y; |
y coordinate of the first pixel. |
gint width; |
number of pixels in the span. |
void (*GdkSpanFunc) (GdkSpan *span, gpointer data);
This defines the type of the function passed to
gdk_region_spans_intersect_foreach().
span : |
a GdkSpan. |
data : |
the user data passed to gdk_region_spans_intersect_foreach().
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void gdk_region_spans_intersect_foreach (GdkRegion *region, GdkSpan *spans, int n_spans, gboolean sorted, GdkSpanFunc function, gpointer data);
Calls a function on each span in the intersection of region and spans.
region : |
a GdkRegion |
spans : |
an array of GdkSpans |
n_spans : |
the length of spans
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sorted : |
TRUE if spans is sorted wrt. the y coordinate
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function : |
function to call on each span in the intersection |
data : |
data to pass to function
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