gtk2/gtk/gtkthemingbackground.c
2012-04-17 08:59:14 +02:00

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/* GTK - The GIMP Toolkit
* Copyright (C) 2010 Carlos Garnacho <carlosg@gnome.org>
* Copyright (C) 2011 Red Hat, Inc.
*
* Authors: Carlos Garnacho <carlosg@gnome.org>
* Cosimo Cecchi <cosimoc@gnome.org>
*
* 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/>.
*/
#include "config.h"
#include "gtkthemingbackgroundprivate.h"
#include "gtkcssimagevalueprivate.h"
#include "gtkcsstypesprivate.h"
#include "gtkthemingengineprivate.h"
#include <math.h>
#include <gdk/gdk.h>
/* this is in case round() is not provided by the compiler,
* such as in the case of C89 compilers, like MSVC
*/
#include "fallback-c89.c"
static void
_gtk_theming_background_apply_window_background (GtkThemingBackground *bg,
cairo_t *cr)
{
if (gtk_style_context_has_class (bg->context, "background"))
{
cairo_set_source_rgba (cr, 1.0, 1.0, 1.0, 0.0); /* transparent */
cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
cairo_paint (cr);
}
}
static void
_gtk_theming_background_apply_origin (GtkThemingBackground *bg)
{
GtkCssArea origin;
cairo_rectangle_t image_rect;
gtk_style_context_get (bg->context, bg->flags,
"background-origin", &origin,
NULL);
/* The default size of the background image depends on the
background-origin value as this affects the top left
and the bottom right corners. */
switch (origin) {
case GTK_CSS_AREA_BORDER_BOX:
image_rect.x = 0;
image_rect.y = 0;
image_rect.width = bg->paint_area.width;
image_rect.height = bg->paint_area.height;
break;
case GTK_CSS_AREA_CONTENT_BOX:
image_rect.x = bg->border.left + bg->padding.left;
image_rect.y = bg->border.top + bg->padding.top;
image_rect.width = bg->paint_area.width - bg->border.left - bg->border.right - bg->padding.left - bg->padding.right;
image_rect.height = bg->paint_area.height - bg->border.top - bg->border.bottom - bg->padding.top - bg->padding.bottom;
break;
case GTK_CSS_AREA_PADDING_BOX:
default:
image_rect.x = bg->border.left;
image_rect.y = bg->border.top;
image_rect.width = bg->paint_area.width - bg->border.left - bg->border.right;
image_rect.height = bg->paint_area.height - bg->border.top - bg->border.bottom;
break;
}
/* XXX: image_rect might have negative width/height here.
* Do we need to do something about it? */
bg->image_rect = image_rect;
}
static void
_gtk_theming_background_apply_clip (GtkThemingBackground *bg)
{
GtkCssArea clip;
gtk_style_context_get (bg->context, bg->flags,
"background-clip", &clip,
NULL);
if (clip == GTK_CSS_AREA_PADDING_BOX)
{
_gtk_rounded_box_shrink (&bg->clip_box,
bg->border.top, bg->border.right,
bg->border.bottom, bg->border.left);
}
else if (clip == GTK_CSS_AREA_CONTENT_BOX)
{
_gtk_rounded_box_shrink (&bg->clip_box,
bg->border.top + bg->padding.top,
bg->border.right + bg->padding.right,
bg->border.bottom + bg->padding.bottom,
bg->border.left + bg->padding.left);
}
}
static void
_gtk_theming_background_get_cover_contain (GtkCssImage *image,
gboolean cover,
double width,
double height,
double *concrete_width,
double *concrete_height)
{
double aspect, image_aspect;
image_aspect = _gtk_css_image_get_aspect_ratio (image);
if (image_aspect == 0.0)
{
*concrete_width = width;
*concrete_height = height;
return;
}
aspect = width / height;
if ((aspect >= image_aspect && cover) ||
(aspect < image_aspect && !cover))
{
*concrete_width = width;
*concrete_height = width / image_aspect;
}
else
{
*concrete_height = height;
*concrete_width = height * image_aspect;
}
}
static void
_gtk_theming_background_paint (GtkThemingBackground *bg,
cairo_t *cr)
{
cairo_save (cr);
_gtk_rounded_box_path (&bg->clip_box, cr);
cairo_clip (cr);
gdk_cairo_set_source_rgba (cr, &bg->bg_color);
cairo_paint (cr);
if (bg->image
&& bg->image_rect.width > 0
&& bg->image_rect.height > 0)
{
GtkCssBackgroundRepeat hrepeat, vrepeat;
const GtkCssBackgroundSize *size;
const GtkCssBackgroundPosition *pos;
double image_width, image_height;
double width, height;
size = _gtk_css_value_get_background_size (_gtk_style_context_peek_property (bg->context, "background-size"));
pos = _gtk_css_value_get_background_position (_gtk_style_context_peek_property (bg->context, "background-position"));
gtk_style_context_get (bg->context, bg->flags,
"background-repeat", &hrepeat,
NULL);
vrepeat = GTK_CSS_BACKGROUND_VERTICAL (hrepeat);
hrepeat = GTK_CSS_BACKGROUND_HORIZONTAL (hrepeat);
width = bg->image_rect.width;
height = bg->image_rect.height;
if (size->contain || size->cover)
_gtk_theming_background_get_cover_contain (bg->image,
size->cover,
width,
height,
&image_width,
&image_height);
else
_gtk_css_image_get_concrete_size (bg->image,
/* note: 0 does the right thing here for 'auto' */
_gtk_css_number_get (&size->width, width),
_gtk_css_number_get (&size->height, height),
width, height,
&image_width, &image_height);
/* optimization */
if (image_width == width)
hrepeat = GTK_CSS_BACKGROUND_NO_REPEAT;
if (image_height == height)
vrepeat = GTK_CSS_BACKGROUND_NO_REPEAT;
cairo_translate (cr, bg->image_rect.x, bg->image_rect.y);
if (hrepeat == GTK_CSS_BACKGROUND_NO_REPEAT && vrepeat == GTK_CSS_BACKGROUND_NO_REPEAT)
{
cairo_translate (cr,
_gtk_css_number_get (&pos->x, bg->image_rect.width - image_width),
_gtk_css_number_get (&pos->y, bg->image_rect.height - image_height));
/* shortcut for normal case */
_gtk_css_image_draw (bg->image, cr, image_width, image_height);
}
else
{
int surface_width, surface_height;
cairo_surface_t *surface;
cairo_t *cr2;
/* If background-repeat is round for one (or both) dimensions,
* there is a second step. The UA must scale the image in that
* dimension (or both dimensions) so that it fits a whole number of
* times in the background positioning area. In the case of the width
* (height is analogous):
*
* If X ≠ 0 is the width of the image after step one and W is the width
* of the background positioning area, then the rounded width
* X' = W / round(W / X) where round() is a function that returns the
* nearest natural number (integer greater than zero).
*
* If background-repeat is round for one dimension only and if
* background-size is auto for the other dimension, then there is
* a third step: that other dimension is scaled so that the original
* aspect ratio is restored.
*/
if (hrepeat == GTK_CSS_BACKGROUND_ROUND)
{
double n = round (width / image_width);
n = MAX (1, n);
if (vrepeat != GTK_CSS_BACKGROUND_ROUND
/* && vsize == auto (it is by default) */)
image_height *= width / (image_width * n);
image_width = width / n;
}
if (vrepeat == GTK_CSS_BACKGROUND_ROUND)
{
double n = round (height / image_height);
n = MAX (1, n);
if (hrepeat != GTK_CSS_BACKGROUND_ROUND
/* && hsize == auto (it is by default) */)
image_width *= height / (image_height * n);
image_height = height / n;
}
/* if hrepeat or vrepeat is 'space', we create a somewhat larger surface
* to store the extra space. */
if (hrepeat == GTK_CSS_BACKGROUND_SPACE)
{
double n = floor (width / image_width);
surface_width = n ? round (width / n) : 0;
}
else
surface_width = round (image_width);
if (vrepeat == GTK_CSS_BACKGROUND_SPACE)
{
double n = floor (height / image_height);
surface_height = n ? round (height / n) : 0;
}
else
surface_height = round (image_height);
surface = cairo_surface_create_similar (cairo_get_target (cr),
CAIRO_CONTENT_COLOR_ALPHA,
surface_width, surface_height);
cr2 = cairo_create (surface);
cairo_translate (cr2,
0.5 * (surface_width - image_width),
0.5 * (surface_height - image_height));
_gtk_css_image_draw (bg->image, cr2, image_width, image_height);
cairo_destroy (cr2);
cairo_set_source_surface (cr, surface,
_gtk_css_number_get (&pos->x, bg->image_rect.width - image_width),
_gtk_css_number_get (&pos->y, bg->image_rect.height - image_height));
cairo_pattern_set_extend (cairo_get_source (cr), CAIRO_EXTEND_REPEAT);
cairo_surface_destroy (surface);
cairo_rectangle (cr,
0, 0,
hrepeat == GTK_CSS_BACKGROUND_NO_REPEAT ? image_width : width,
vrepeat == GTK_CSS_BACKGROUND_NO_REPEAT ? image_height : height);
cairo_fill (cr);
}
}
cairo_restore (cr);
}
static void
_gtk_theming_background_apply_shadow (GtkThemingBackground *bg,
cairo_t *cr)
{
_gtk_css_shadow_value_paint_box (_gtk_style_context_peek_property (bg->context, "box-shadow"),
cr,
&bg->padding_box);
}
static void
_gtk_theming_background_init_context (GtkThemingBackground *bg)
{
bg->flags = gtk_style_context_get_state (bg->context);
gtk_style_context_get_border (bg->context, bg->flags, &bg->border);
gtk_style_context_get_padding (bg->context, bg->flags, &bg->padding);
gtk_style_context_get_background_color (bg->context, bg->flags, &bg->bg_color);
/* In the CSS box model, by default the background positioning area is
* the padding-box, i.e. all the border-box minus the borders themselves,
* which determines also its default size, see
* http://dev.w3.org/csswg/css3-background/#background-origin
*
* In the future we might want to support different origins or clips, but
* right now we just shrink to the default.
*/
_gtk_rounded_box_init_rect (&bg->padding_box, 0, 0, bg->paint_area.width, bg->paint_area.height);
_gtk_rounded_box_apply_border_radius_for_context (&bg->padding_box, bg->context, bg->flags, bg->junction);
bg->clip_box = bg->padding_box;
_gtk_rounded_box_shrink (&bg->padding_box,
bg->border.top, bg->border.right,
bg->border.bottom, bg->border.left);
_gtk_theming_background_apply_clip (bg);
_gtk_theming_background_apply_origin (bg);
bg->image = _gtk_css_image_value_get_image (_gtk_style_context_peek_property (bg->context, "background-image"));
}
void
_gtk_theming_background_init (GtkThemingBackground *bg,
GtkThemingEngine *engine,
gdouble x,
gdouble y,
gdouble width,
gdouble height,
GtkJunctionSides junction)
{
GtkStyleContext *context;
g_assert (bg != NULL);
context = _gtk_theming_engine_get_context (engine);
_gtk_theming_background_init_from_context (bg, context,
x, y, width, height,
junction);
}
void
_gtk_theming_background_init_from_context (GtkThemingBackground *bg,
GtkStyleContext *context,
gdouble x,
gdouble y,
gdouble width,
gdouble height,
GtkJunctionSides junction)
{
g_assert (bg != NULL);
bg->context = context;
bg->paint_area.x = x;
bg->paint_area.y = y;
bg->paint_area.width = width;
bg->paint_area.height = height;
bg->image = NULL;
bg->junction = junction;
_gtk_theming_background_init_context (bg);
}
void
_gtk_theming_background_render (GtkThemingBackground *bg,
cairo_t *cr)
{
cairo_save (cr);
cairo_translate (cr, bg->paint_area.x, bg->paint_area.y);
_gtk_theming_background_apply_window_background (bg, cr);
_gtk_theming_background_paint (bg, cr);
_gtk_theming_background_apply_shadow (bg, cr);
cairo_restore (cr);
}
gboolean
_gtk_theming_background_has_background_image (GtkThemingBackground *bg)
{
return (bg->image != NULL) ? TRUE : FALSE;
}