зеркало из https://github.com/mozilla/gecko-dev.git
128 строки
3.2 KiB
C
128 строки
3.2 KiB
C
/* Libart_LGPL - library of basic graphic primitives
|
|
* Copyright (C) 1998 Raph Levien
|
|
*
|
|
* This library is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Library 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
|
|
* Library General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Library General Public
|
|
* License along with this library; if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
* Boston, MA 02111-1307, USA.
|
|
*/
|
|
|
|
#include "config.h"
|
|
#include "art_rgb_affine_private.h"
|
|
|
|
#include <math.h>
|
|
#include "art_misc.h"
|
|
#include "art_point.h"
|
|
#include "art_affine.h"
|
|
|
|
/* Private functions for the rgb affine image compositors - primarily,
|
|
the determination of runs, eliminating the need for source image
|
|
bbox calculation in the inner loop. */
|
|
|
|
/* Determine a "run", such that the inverse affine of all pixels from
|
|
(x0, y) inclusive to (x1, y) exclusive fit within the bounds
|
|
of the source image.
|
|
|
|
Initial values of x0, x1, and result values stored in first two
|
|
pointer arguments.
|
|
*/
|
|
|
|
#define EPSILON 1e-6
|
|
|
|
void
|
|
art_rgb_affine_run (int *p_x0, int *p_x1, int y,
|
|
int src_width, int src_height,
|
|
const double affine[6])
|
|
{
|
|
int x0, x1;
|
|
double z;
|
|
double x_intercept;
|
|
int xi;
|
|
|
|
x0 = *p_x0;
|
|
x1 = *p_x1;
|
|
|
|
/* do left and right edges */
|
|
if (affine[0] > EPSILON)
|
|
{
|
|
z = affine[2] * (y + 0.5) + affine[4];
|
|
x_intercept = -z / affine[0];
|
|
xi = ceil (x_intercept + EPSILON - 0.5);
|
|
if (xi > x0)
|
|
x0 = xi;
|
|
x_intercept = (-z + src_width) / affine[0];
|
|
xi = ceil (x_intercept - EPSILON - 0.5);
|
|
if (xi < x1)
|
|
x1 = xi;
|
|
}
|
|
else if (affine[0] < -EPSILON)
|
|
{
|
|
z = affine[2] * (y + 0.5) + affine[4];
|
|
x_intercept = (-z + src_width) / affine[0];
|
|
xi = ceil (x_intercept + EPSILON - 0.5);
|
|
if (xi > x0)
|
|
x0 = xi;
|
|
x_intercept = -z / affine[0];
|
|
xi = ceil (x_intercept - EPSILON - 0.5);
|
|
if (xi < x1)
|
|
x1 = xi;
|
|
}
|
|
else
|
|
{
|
|
z = affine[2] * (y + 0.5) + affine[4];
|
|
if (z < 0 || z >= src_width)
|
|
{
|
|
*p_x1 = *p_x0;
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* do top and bottom edges */
|
|
if (affine[1] > EPSILON)
|
|
{
|
|
z = affine[3] * (y + 0.5) + affine[5];
|
|
x_intercept = -z / affine[1];
|
|
xi = ceil (x_intercept + EPSILON - 0.5);
|
|
if (xi > x0)
|
|
x0 = xi;
|
|
x_intercept = (-z + src_height) / affine[1];
|
|
xi = ceil (x_intercept - EPSILON - 0.5);
|
|
if (xi < x1)
|
|
x1 = xi;
|
|
}
|
|
else if (affine[1] < -EPSILON)
|
|
{
|
|
z = affine[3] * (y + 0.5) + affine[5];
|
|
x_intercept = (-z + src_height) / affine[1];
|
|
xi = ceil (x_intercept + EPSILON - 0.5);
|
|
if (xi > x0)
|
|
x0 = xi;
|
|
x_intercept = -z / affine[1];
|
|
xi = ceil (x_intercept - EPSILON - 0.5);
|
|
if (xi < x1)
|
|
x1 = xi;
|
|
}
|
|
else
|
|
{
|
|
z = affine[3] * (y + 0.5) + affine[5];
|
|
if (z < 0 || z >= src_height)
|
|
{
|
|
*p_x1 = *p_x0;
|
|
return;
|
|
}
|
|
}
|
|
|
|
*p_x0 = x0;
|
|
*p_x1 = x1;
|
|
}
|