gtk/gdk/gdkrectangleprivate.h
Benjamin Otte 11aaa29a69 wayland: Use wl_surface_damage_buffer() in Cairo
... when it is available.

Also introduce the new function gdk_rectangle_transform_affine(), which
looks like overkill for this purpose, but I'm about to use it elsewhere.
2023-04-29 05:07:03 +02:00

58 lines
1.8 KiB
C

#pragma once
#include "gdkrectangle.h"
#include <math.h>
G_BEGIN_DECLS
/*
* gdk_rectangle_transform_affine:
* @src: the rectangle to transform
* @scale_x: scale factor in the X direction. The scale factor
* may be negative or 0.
* @scale_y: scale factor in the Y direction. The scale factor
* may be negative or 0.
* @offset_x: offset of result in X direction.
* @offset_y: offset of result in Y direction.
* @dest: (out caller-allocates): destination rectangle, may be
* identical to @src
*
* Does an affine transform of the source rectangle and stores the
* result in the dest rectangle. If the destination rectangle does
* not fit on integer bounds, the result will be enlarged to make it
* fit.
* (Fun fact: This means with a scale of 0 and an offset of 0.5,
* the resulting rect will have a width of 1.)
*
* The width and height of the result will be positive, even if the
* src rectangle or the scale were negative.
*
* This function can be used with the output of
* gsk_transform_to_affine().
**/
static inline void
gdk_rectangle_transform_affine (const GdkRectangle *src,
float scale_x,
float scale_y,
float offset_x,
float offset_y,
GdkRectangle *dest)
{
float x1, x2, y1, y2;
x1 = offset_x + src->x * scale_x;
x2 = offset_x + (src->x + src->width) * scale_x;
y1 = offset_y + src->y * scale_y;
y2 = offset_y + (src->y + src->height) * scale_y;
dest->x = floorf (MIN (x1, x2));
dest->y = floorf (MIN (y1, y2));
dest->width = ceilf (MAX (x1, x2)) - dest->x;
dest->height = ceilf (MAX (y1, y2)) - dest->y;
}
G_END_DECLS