gtk2/gdk/gdkrectangle.c
Matthias Clasen 51f05a00ae Clarify docs for gdk_rectangle_union
This function does not ignore empty rectangles. Since this
is a fairly subtle point about the behavior, it is worth
spelling this out in the documentation. We've had a bug
open about this for a long time:

https://bugzilla.gnome.org/show_bug.cgi?id=464528
2016-01-20 13:44:34 -05:00

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/* GDK - The GIMP Drawing Kit
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
#include "config.h"
#include "gdkrectangle.h"
#include <cairo-gobject.h>
/**
* SECTION:regions
* @Short_description: Simple graphical data types
* @Title: Points and Rectangles
*
* GDK provides the #GdkPoint and #GdkRectangle data types for representing pixels
* and sets of pixels on the screen. Together with Cairos #cairo_region_t data
* type, they make up the central types for representing graphical data.
*
* A #GdkPoint represents an x and y coordinate of a point.
*
* A #GdkRectangle represents 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().
*
* #cairo_region_t is usually used for managing clipping of graphical operations.
*/
/**
* gdk_rectangle_union:
* @src1: a #GdkRectangle
* @src2: a #GdkRectangle
* @dest: (out): return location for the union of @src1 and @src2
*
* 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.
*
* Note that this function does not ignore 'empty' rectangles (ie. with
* zero width or height).
*/
void
gdk_rectangle_union (const GdkRectangle *src1,
const GdkRectangle *src2,
GdkRectangle *dest)
{
gint dest_x, dest_y;
g_return_if_fail (src1 != NULL);
g_return_if_fail (src2 != NULL);
g_return_if_fail (dest != NULL);
dest_x = MIN (src1->x, src2->x);
dest_y = MIN (src1->y, src2->y);
dest->width = MAX (src1->x + src1->width, src2->x + src2->width) - dest_x;
dest->height = MAX (src1->y + src1->height, src2->y + src2->height) - dest_y;
dest->x = dest_x;
dest->y = dest_y;
}
/**
* gdk_rectangle_intersect:
* @src1: a #GdkRectangle
* @src2: a #GdkRectangle
* @dest: (out caller-allocates) (allow-none): return location for the
* intersection of @src1 and @src2, or %NULL
*
* 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, @dests 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.
*
* Returns: %TRUE if the rectangles intersect.
*/
gboolean
gdk_rectangle_intersect (const GdkRectangle *src1,
const GdkRectangle *src2,
GdkRectangle *dest)
{
gint dest_x, dest_y;
gint dest_x2, dest_y2;
gint return_val;
g_return_val_if_fail (src1 != NULL, FALSE);
g_return_val_if_fail (src2 != NULL, FALSE);
return_val = FALSE;
dest_x = MAX (src1->x, src2->x);
dest_y = MAX (src1->y, src2->y);
dest_x2 = MIN (src1->x + src1->width, src2->x + src2->width);
dest_y2 = MIN (src1->y + src1->height, src2->y + src2->height);
if (dest_x2 > dest_x && dest_y2 > dest_y)
{
if (dest)
{
dest->x = dest_x;
dest->y = dest_y;
dest->width = dest_x2 - dest_x;
dest->height = dest_y2 - dest_y;
}
return_val = TRUE;
}
else if (dest)
{
dest->width = 0;
dest->height = 0;
}
return return_val;
}
/**
* gdk_rectangle_equal:
* @rect1: a #GdkRectangle
* @rect2: a #GdkRectangle
*
* Checks if the two given rectangles are equal.
*
* Returns: %TRUE if the rectangles are equal.
*
* Since: 3.20
*/
gboolean
gdk_rectangle_equal (const GdkRectangle *rect1,
const GdkRectangle *rect2)
{
return rect1->x == rect2->x
&& rect1->y == rect2->y
&& rect1->width == rect2->width
&& rect1->height == rect2->height;
}
static GdkRectangle *
gdk_rectangle_copy (const GdkRectangle *rectangle)
{
GdkRectangle *result = g_new (GdkRectangle, 1);
*result = *rectangle;
return result;
}
/* Transforms between identical boxed types.
*/
static void
gdk_rectangle_value_transform_rect (const GValue *src_value, GValue *dest_value)
{
g_value_set_boxed (dest_value, g_value_get_boxed (src_value));
}
/* Allow GValue transformation between the identical structs
* cairo_rectangle_int_t and GdkRectangle.
*/
static void
gdk_rectangle_register_value_transform_funcs (GType gtype_gdk_rectangle)
{
/* This function is called from the first call to gdk_rectangle_get_type(),
* before g_once_init_leave() has been called.
* If gdk_rectangle_get_type() is called from here (e.g. via
* GDK_TYPE_RECTANGLE), the program will wait indefinitely at
* g_once_init_enter() in gdk_rectangle_get_type().
*/
g_value_register_transform_func (CAIRO_GOBJECT_TYPE_RECTANGLE_INT,
gtype_gdk_rectangle,
gdk_rectangle_value_transform_rect);
g_value_register_transform_func (gtype_gdk_rectangle,
CAIRO_GOBJECT_TYPE_RECTANGLE_INT,
gdk_rectangle_value_transform_rect);
}
G_DEFINE_BOXED_TYPE_WITH_CODE (GdkRectangle, gdk_rectangle,
gdk_rectangle_copy,
g_free,
gdk_rectangle_register_value_transform_funcs (g_define_type_id))