Sets our main struct and passes it to the parent class
the main Gtk struct as a void*
Calculates the intersection of two rectangles. It is allowed for dest to be the same as either src1 or src2. If the rectangles do not intersect, dest's width and height is set to 0 and its x and y values are undefined. If you are only interested in whether the rectangles intersect, but not in the intersecting area itself, pass NULL for 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.
the main Gtk struct
Description 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().