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Compute extents of cairo_traps_t on the fly using approximate method which is correct given the way cairo generates trapezoids.

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Avoid zero-dimensioned pixmaps
This commit is contained in:
Keith Packard 2004-10-12 14:17:23 +00:00
parent 047ce33600
commit f9b0020850
6 changed files with 126 additions and 100 deletions
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11
ChangeLog
View file

@ -1,3 +1,14 @@
2004-10-12 Keith Packard <keithp@keithp.com>
* src/cairo_traps.c: (_cairo_traps_init), (_cairo_traps_add_trap),
(_cairo_traps_extents):
* src/cairoint.h:
Compute extents of cairo_traps_t on the fly using approximate
method which is correct given the way cairo generates trapezoids.
* src/cairo_xlib_surface.c: (_cairo_xlib_surface_create_similar):
Avoid zero-dimensioned pixmaps
2004-10-12 Carl Worth <cworth@cworth.org>
* src/cairo_pen.c: Fix a few typos in pen vertex math description.

105
src/cairo-traps.c
View file

@ -1,23 +1,36 @@
/*
* Copyright © 2002 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of Keith Packard not be used in
* advertising or publicity pertaining to distribution of the software without
* specific, written prior permission. Keith Packard makes no
* representations about the suitability of this software for any purpose. It
* is provided "as is" without express or implied warranty.
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
* The Original Code is the cairo graphics library.
*
* The Initial Developer of the Original Code is Keith Packard
*
* Contributor(s):
* Keith R. Packard <keithp@keithp.com>
* Carl D. Worth <cworth@isi.edu>
*
* 2002-07-15: Converted from XRenderCompositeDoublePoly to cairo_trap. Carl D. Worth
*/
@ -62,6 +75,8 @@ _cairo_traps_init (cairo_traps_t *traps)
traps->traps_size = 0;
traps->traps = NULL;
traps->extents.p1.x = traps->extents.p1.y = CAIRO_MAXSHORT << 16;
traps->extents.p2.x = traps->extents.p2.y = CAIRO_MINSHORT << 16;
}
void
@ -87,7 +102,8 @@ _cairo_traps_add_trap (cairo_traps_t *traps, cairo_fixed_t top, cairo_fixed_t bo
}
if (traps->num_traps >= traps->traps_size) {
status = _cairo_traps_grow_by (traps, CAIRO_TRAPS_GROWTH_INC);
int inc = traps->traps_size ? traps->traps_size : 32;
status = _cairo_traps_grow_by (traps, inc);
if (status)
return status;
}
@ -98,6 +114,28 @@ _cairo_traps_add_trap (cairo_traps_t *traps, cairo_fixed_t top, cairo_fixed_t bo
trap->left = *left;
trap->right = *right;
if (top < traps->extents.p1.y)
traps->extents.p1.y = top;
if (bottom > traps->extents.p2.y)
traps->extents.p2.y = bottom;
/*
* This isn't generally accurate, but it is close enough for
* this purpose. Assuming that the left and right segments always
* contain the trapezoid vertical extents, these compares will
* yield a containing box. Assuming that the points all come from
* the same figure which will eventually be completely drawn, then
* the compares will yield the correct overall extents
*/
if (left->p1.x < traps->extents.p1.x)
traps->extents.p1.x = left->p1.x;
if (left->p2.x < traps->extents.p1.x)
traps->extents.p1.x = left->p2.x;
if (right->p1.x > traps->extents.p2.x)
traps->extents.p2.x = right->p1.x;
if (right->p2.x > traps->extents.p2.x)
traps->extents.p2.x = right->p2.x;
traps->num_traps++;
return CAIRO_STATUS_SUCCESS;
@ -673,39 +711,8 @@ _cairo_traps_contain (cairo_traps_t *traps, double x, double y)
return 0;
}
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
static void
_cairo_trap_extents (cairo_trapezoid_t *t, cairo_box_t *extents)
{
cairo_fixed_t x;
if (t->top < extents->p1.y)
extents->p1.y = t->top;
if (t->bottom > extents->p2.y)
extents->p2.y = t->bottom;
x = MIN (_compute_x (&t->left, t->top),
_compute_x (&t->left, t->bottom));
if (x < extents->p1.x)
extents->p1.x = x;
x = MAX (_compute_x (&t->right, t->top),
_compute_x (&t->right, t->bottom));
if (x > extents->p2.x)
extents->p2.x = x;
}
void
_cairo_traps_extents (cairo_traps_t *traps, cairo_box_t *extents)
{
int i;
extents->p1.x = extents->p1.y = CAIRO_MAXSHORT << 16;
extents->p2.x = extents->p2.y = CAIRO_MINSHORT << 16;
for (i = 0; i < traps->num_traps; i++)
_cairo_trap_extents (&traps->traps[i], extents);
*extents = traps->extents;
}

2
src/cairo-xlib-surface.c
View file

@ -145,7 +145,7 @@ _cairo_xlib_surface_create_similar (void *abstract_src,
scr = DefaultScreen (dpy);
pix = XCreatePixmap (dpy, DefaultRootWindow (dpy),
width, height,
width <= 0 ? 1 : width, height <= 0 ? 1 : height,
_CAIRO_FORMAT_DEPTH (format));
surface = (cairo_xlib_surface_t *)

105
src/cairo_traps.c
View file

@ -1,23 +1,36 @@
/*
* Copyright © 2002 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of Keith Packard not be used in
* advertising or publicity pertaining to distribution of the software without
* specific, written prior permission. Keith Packard makes no
* representations about the suitability of this software for any purpose. It
* is provided "as is" without express or implied warranty.
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
* The Original Code is the cairo graphics library.
*
* The Initial Developer of the Original Code is Keith Packard
*
* Contributor(s):
* Keith R. Packard <keithp@keithp.com>
* Carl D. Worth <cworth@isi.edu>
*
* 2002-07-15: Converted from XRenderCompositeDoublePoly to cairo_trap. Carl D. Worth
*/
@ -62,6 +75,8 @@ _cairo_traps_init (cairo_traps_t *traps)
traps->traps_size = 0;
traps->traps = NULL;
traps->extents.p1.x = traps->extents.p1.y = CAIRO_MAXSHORT << 16;
traps->extents.p2.x = traps->extents.p2.y = CAIRO_MINSHORT << 16;
}
void
@ -87,7 +102,8 @@ _cairo_traps_add_trap (cairo_traps_t *traps, cairo_fixed_t top, cairo_fixed_t bo
}
if (traps->num_traps >= traps->traps_size) {
status = _cairo_traps_grow_by (traps, CAIRO_TRAPS_GROWTH_INC);
int inc = traps->traps_size ? traps->traps_size : 32;
status = _cairo_traps_grow_by (traps, inc);
if (status)
return status;
}
@ -98,6 +114,28 @@ _cairo_traps_add_trap (cairo_traps_t *traps, cairo_fixed_t top, cairo_fixed_t bo
trap->left = *left;
trap->right = *right;
if (top < traps->extents.p1.y)
traps->extents.p1.y = top;
if (bottom > traps->extents.p2.y)
traps->extents.p2.y = bottom;
/*
* This isn't generally accurate, but it is close enough for
* this purpose. Assuming that the left and right segments always
* contain the trapezoid vertical extents, these compares will
* yield a containing box. Assuming that the points all come from
* the same figure which will eventually be completely drawn, then
* the compares will yield the correct overall extents
*/
if (left->p1.x < traps->extents.p1.x)
traps->extents.p1.x = left->p1.x;
if (left->p2.x < traps->extents.p1.x)
traps->extents.p1.x = left->p2.x;
if (right->p1.x > traps->extents.p2.x)
traps->extents.p2.x = right->p1.x;
if (right->p2.x > traps->extents.p2.x)
traps->extents.p2.x = right->p2.x;
traps->num_traps++;
return CAIRO_STATUS_SUCCESS;
@ -673,39 +711,8 @@ _cairo_traps_contain (cairo_traps_t *traps, double x, double y)
return 0;
}
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
static void
_cairo_trap_extents (cairo_trapezoid_t *t, cairo_box_t *extents)
{
cairo_fixed_t x;
if (t->top < extents->p1.y)
extents->p1.y = t->top;
if (t->bottom > extents->p2.y)
extents->p2.y = t->bottom;
x = MIN (_compute_x (&t->left, t->top),
_compute_x (&t->left, t->bottom));
if (x < extents->p1.x)
extents->p1.x = x;
x = MAX (_compute_x (&t->right, t->top),
_compute_x (&t->right, t->bottom));
if (x > extents->p2.x)
extents->p2.x = x;
}
void
_cairo_traps_extents (cairo_traps_t *traps, cairo_box_t *extents)
{
int i;
extents->p1.x = extents->p1.y = CAIRO_MAXSHORT << 16;
extents->p2.x = extents->p2.y = CAIRO_MINSHORT << 16;
for (i = 0; i < traps->num_traps; i++)
_cairo_trap_extents (&traps->traps[i], extents);
*extents = traps->extents;
}

2
src/cairo_xlib_surface.c
View file

@ -145,7 +145,7 @@ _cairo_xlib_surface_create_similar (void *abstract_src,
scr = DefaultScreen (dpy);
pix = XCreatePixmap (dpy, DefaultRootWindow (dpy),
width, height,
width <= 0 ? 1 : width, height <= 0 ? 1 : height,
_CAIRO_FORMAT_DEPTH (format));
surface = (cairo_xlib_surface_t *)

1
src/cairoint.h
View file

@ -700,6 +700,7 @@ typedef struct cairo_traps {
cairo_trapezoid_t *traps;
int num_traps;
int traps_size;
cairo_box_t extents;
} cairo_traps_t;
#define CAIRO_FONT_FAMILY_DEFAULT "serif"