gtk/docs/reference/gdk/tmpl/regions.sgml
Owen Taylor a7557dc8f9 Fix some docs duplicated between templates and inline.
Thu Apr 25 22:37:58 2002  Owen Taylor  <otaylor@redhat.com>

        * gdk/tmpl/{events,input_devices,region,x_interaction}.sgml:
        Fix some docs duplicated between templates and inline.
2002-04-26 02:39:49 +00:00

310 lines
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<!-- ##### SECTION Title ##### -->
Points, Rectangles and Regions
<!-- ##### SECTION Short_Description ##### -->
simple graphical data types.
<!-- ##### SECTION Long_Description ##### -->
<para>
GDK provides the #GdkPoint, #GdkRectangle, #GdkRegion and #GdkSpan data types
for representing pixels and sets of pixels on the screen.
</para>
<para>
#GdkPoint is a simple structure containing an x and y coordinate of a point.
</para>
<para>
#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().
</para>
<para>
#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()).
</para>
<para>
#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().
</para>
<!-- ##### SECTION See_Also ##### -->
<para>
</para>
<!-- ##### STRUCT GdkPoint ##### -->
<para>
Defines the x and y coordinates of a point.
</para>
@x: the x coordinate of the point.
@y: the y coordinate of the point.
<!-- ##### STRUCT GdkRectangle ##### -->
<para>
Defines the position and size of a rectangle.
</para>
@x: the x coordinate of the left edge of the rectangle.
@y: the y coordinate of the top of the rectangle.
@width: the width of the rectangle.
@height: the height of the rectangle.
<!-- ##### FUNCTION gdk_rectangle_intersect ##### -->
<para>
Calculates the intersection of two rectangles.
</para>
@src1: a #GdkRectangle.
@src2: a #GdkRectangle.
@dest: the intersection of @src1 and @src2.
@Returns: %TRUE if the rectangles intersect.
<!-- ##### FUNCTION gdk_rectangle_union ##### -->
<para>
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.
</para>
@src1: a #GdkRectangle.
@src2: a #GdkRectangle.
@dest: the union of @src1 and @src2.
<!-- ##### STRUCT GdkRegion ##### -->
<para>
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.
</para>
<!-- ##### FUNCTION gdk_region_new ##### -->
<para>
Creates a new empty #GdkRegion.
</para>
@Returns: a new empty #GdkRegion.
<!-- ##### FUNCTION gdk_region_polygon ##### -->
<para>
Creates a new #GdkRegion using the polygon defined by a number of points.
</para>
@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 ##### -->
<para>
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.
</para>
@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.
<!-- ##### FUNCTION gdk_region_copy ##### -->
<para>
</para>
@region:
@Returns:
<!-- ##### FUNCTION gdk_region_rectangle ##### -->
<para>
</para>
@rectangle:
@Returns:
<!-- ##### FUNCTION gdk_region_destroy ##### -->
<para>
Destroys a #GdkRegion.
</para>
@region: a #GdkRegion.
<!-- ##### FUNCTION gdk_region_get_clipbox ##### -->
<para>
Returns the smallest rectangle which includes the entire #GdkRegion.
</para>
@region: a #GdkRegion.
@rectangle: returns the smallest rectangle which includes all of @region.
<!-- ##### FUNCTION gdk_region_get_rectangles ##### -->
<para>
</para>
@region:
@rectangles:
@n_rectangles:
<!-- ##### FUNCTION gdk_region_empty ##### -->
<para>
Returns %TRUE if the #GdkRegion is empty.
</para>
@region: a #GdkRegion.
@Returns: %TRUE if @region is empty.
<!-- ##### FUNCTION gdk_region_equal ##### -->
<para>
Returns %TRUE if the two regions are the same.
</para>
@region1: a #GdkRegion.
@region2: a #GdkRegion.
@Returns: %TRUE if @region1 and @region2 are equal.
<!-- ##### FUNCTION gdk_region_point_in ##### -->
<para>
Returns %TRUE if a point is in a region.
</para>
@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.
<!-- ##### FUNCTION gdk_region_rect_in ##### -->
<para>
Tests whether a rectangle is within a region.
</para>
@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 ##### -->
<para>
Specifies the possible values returned by gdk_region_rect_in().
</para>
@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.
<!-- ##### FUNCTION gdk_region_offset ##### -->
<para>
Moves a region the specified distance.
</para>
@region: a #GdkRegion.
@dx: the distance to move the region horizontally.
@dy: the distance to move the region vertically.
<!-- ##### FUNCTION gdk_region_shrink ##### -->
<para>
Resizes a region by the specified amount.
Positive values shrink the region. Negative values expand it.
</para>
@region: a #GdkRegion.
@dx: the number of pixels to shrink the region horizontally.
@dy: the number of pixels to shrink the region vertically.
<!-- ##### FUNCTION gdk_region_union_with_rect ##### -->
<para>
</para>
@region:
@rect:
<!-- ##### FUNCTION gdk_region_intersect ##### -->
<para>
</para>
@source1:
@source2:
<!-- ##### FUNCTION gdk_region_union ##### -->
<para>
</para>
@source1:
@source2:
<!-- ##### FUNCTION gdk_region_subtract ##### -->
<para>
</para>
@source1:
@source2:
<!-- ##### FUNCTION gdk_region_xor ##### -->
<para>
</para>
@source1:
@source2:
<!-- ##### STRUCT GdkSpan ##### -->
<para>
A GdkSpan represents a horizontal line of pixels starting
at the pixel with coordinates @x, @y and ending before @x + @width, @y.
</para>
@x: x coordinate of the first pixel.
@y: y coordinate of the first pixel.
@width: number of pixels in the span.
<!-- ##### USER_FUNCTION GdkSpanFunc ##### -->
<para>
This defines the type of the function passed to
gdk_region_spans_intersect_foreach().
</para>
@span: a #GdkSpan.
@data: the user data passed to gdk_region_spans_intersect_foreach().
<!-- ##### FUNCTION gdk_region_spans_intersect_foreach ##### -->
<para>
Calls a function on each span in the intersection of @region and
@spans.
</para>
@region: a #GdkRegion.
@spans: an array of #GdkSpans.
@n_spans: the length of @spans.
@sorted: %TRUE if @spans is sorted wrt. the y coordinate.
@function: function to call on each span in the intersection.
@data: data to pass to @function.