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gtk/gdk/gdkpixbuf-render.c

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/* GdkPixbuf library - Rendering functions
*
* Copyright (C) 1999 The Free Software Foundation
*
* Author: Federico Mena-Quintero <federico@gimp.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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <gdk/gdk.h>
#include <gdk-pixbuf/gdk-pixbuf.h>
#include "gdkpixbuf.h"
#include "gdkscreen.h"
#include "gdkinternals.h"
/**
* gdk_pixbuf_render_threshold_alpha:
* @pixbuf: A pixbuf.
* @bitmap: Bitmap where the bilevel mask will be painted to.
* @src_x: Source X coordinate.
* @src_y: source Y coordinate.
* @dest_x: Destination X coordinate.
* @dest_y: Destination Y coordinate.
* @width: Width of region to threshold, or -1 to use pixbuf width
* @height: Height of region to threshold, or -1 to use pixbuf height
* @alpha_threshold: Opacity values below this will be painted as zero; all
* other values will be painted as one.
*
* Takes the opacity values in a rectangular portion of a pixbuf and thresholds
* them to produce a bi-level alpha mask that can be used as a clipping mask for
* a drawable.
*
**/
void
gdk_pixbuf_render_threshold_alpha (GdkPixbuf *pixbuf,
GdkBitmap *bitmap,
int src_x,
int src_y,
int dest_x,
int dest_y,
int width,
int height,
int alpha_threshold)
{
GdkGC *gc;
GdkColor color;
int x, y;
guchar *p;
int start, start_status;
int status;
g_return_if_fail (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB);
g_return_if_fail (gdk_pixbuf_get_n_channels (pixbuf) == 3 ||
gdk_pixbuf_get_n_channels (pixbuf) == 4);
g_return_if_fail (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8);
if (width == -1)
width = gdk_pixbuf_get_width (pixbuf);
if (height == -1)
height = gdk_pixbuf_get_height (pixbuf);
g_return_if_fail (bitmap != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= gdk_pixbuf_get_width (pixbuf));
g_return_if_fail (src_y >= 0 && src_y + height <= gdk_pixbuf_get_height (pixbuf));
g_return_if_fail (alpha_threshold >= 0 && alpha_threshold <= 255);
if (width == 0 || height == 0)
return;
gc = _gdk_drawable_get_scratch_gc (bitmap, FALSE);
if (!gdk_pixbuf_get_has_alpha (pixbuf))
{
color.pixel = (alpha_threshold == 255) ? 0 : 1;
gdk_gc_set_foreground (gc, &color);
gdk_draw_rectangle (bitmap, gc, TRUE, dest_x, dest_y, width, height);
return;
}
color.pixel = 0;
gdk_gc_set_foreground (gc, &color);
gdk_draw_rectangle (bitmap, gc, TRUE, dest_x, dest_y, width, height);
color.pixel = 1;
gdk_gc_set_foreground (gc, &color);
for (y = 0; y < height; y++)
{
p = (gdk_pixbuf_get_pixels (pixbuf) + (y + src_y) * gdk_pixbuf_get_rowstride (pixbuf) + src_x * gdk_pixbuf_get_n_channels (pixbuf)
+ gdk_pixbuf_get_n_channels (pixbuf) - 1);
start = 0;
start_status = *p < alpha_threshold;
for (x = 0; x < width; x++)
{
status = *p < alpha_threshold;
if (status != start_status)
{
if (!start_status)
gdk_draw_line (bitmap, gc,
start + dest_x, y + dest_y,
x - 1 + dest_x, y + dest_y);
start = x;
start_status = status;
}
p += gdk_pixbuf_get_n_channels (pixbuf);
}
if (!start_status)
gdk_draw_line (bitmap, gc,
start + dest_x, y + dest_y,
x - 1 + dest_x, y + dest_y);
}
}
/**
* gdk_pixbuf_render_pixmap_and_mask:
* @pixbuf: A pixbuf.
* @pixmap_return: Location to store a pointer to the created pixmap,
* or %NULL if the pixmap is not needed.
* @mask_return: Location to store a pointer to the created mask,
* or %NULL if the mask is not needed.
* @alpha_threshold: Threshold value for opacity values.
*
* Creates a pixmap and a mask bitmap which are returned in the @pixmap_return
* and @mask_return arguments, respectively, and renders a pixbuf and its
* corresponding thresholded alpha mask to them. This is merely a convenience
* function; applications that need to render pixbufs with dither offsets or to
* given drawables should use gdk_draw_pixbuf() and gdk_pixbuf_render_threshold_alpha().
*
* The pixmap that is created is created for the colormap returned
* by gdk_rgb_get_colormap(). You normally will want to instead use
* the actual colormap for a widget, and use
* gdk_pixbuf_render_pixmap_and_mask_for_colormap().
*
* If the pixbuf does not have an alpha channel, then *@mask_return will be set
* to %NULL.
**/
void
gdk_pixbuf_render_pixmap_and_mask (GdkPixbuf *pixbuf,
GdkPixmap **pixmap_return,
GdkBitmap **mask_return,
int alpha_threshold)
{
gdk_pixbuf_render_pixmap_and_mask_for_colormap (pixbuf,
gdk_rgb_get_colormap (),
pixmap_return, mask_return,
alpha_threshold);
}
/**
* gdk_pixbuf_render_pixmap_and_mask_for_colormap:
* @pixbuf: A pixbuf.
* @colormap: A #GdkColormap
* @pixmap_return: Location to store a pointer to the created pixmap,
* or %NULL if the pixmap is not needed.
* @mask_return: Location to store a pointer to the created mask,
* or %NULL if the mask is not needed.
* @alpha_threshold: Threshold value for opacity values.
*
* Creates a pixmap and a mask bitmap which are returned in the @pixmap_return
* and @mask_return arguments, respectively, and renders a pixbuf and its
* corresponding tresholded alpha mask to them. This is merely a convenience
* function; applications that need to render pixbufs with dither offsets or to
* given drawables should use gdk_draw_pixbuf(), and gdk_pixbuf_render_threshold_alpha().
*
* The pixmap that is created uses the #GdkColormap specified by @colormap.
* This colormap must match the colormap of the window where the pixmap
* will eventually be used or an error will result.
*
* If the pixbuf does not have an alpha channel, then *@mask_return will be set
* to %NULL.
**/
void
gdk_pixbuf_render_pixmap_and_mask_for_colormap (GdkPixbuf *pixbuf,
GdkColormap *colormap,
GdkPixmap **pixmap_return,
GdkBitmap **mask_return,
int alpha_threshold)
{
GdkScreen *screen;
g_return_if_fail (GDK_IS_PIXBUF (pixbuf));
g_return_if_fail (GDK_IS_COLORMAP (colormap));
screen = gdk_colormap_get_screen (colormap);
if (pixmap_return)
{
GdkGC *gc;
*pixmap_return = gdk_pixmap_new (gdk_screen_get_root_window (screen),
gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf),
gdk_colormap_get_visual (colormap)->depth);
gdk_drawable_set_colormap (GDK_DRAWABLE (*pixmap_return), colormap);
gc = _gdk_drawable_get_scratch_gc (*pixmap_return, FALSE);
/* If the pixbuf has an alpha channel, using gdk_pixbuf_draw would give
* random pixel values in the area that are within the mask, but semi-
* transparent. So we treat the pixbuf like a pixbuf without alpha channel;
* see bug #487865.
*/
if (gdk_pixbuf_get_has_alpha (pixbuf))
gdk_draw_rgb_32_image (*pixmap_return, gc,
0, 0,
gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf),
GDK_RGB_DITHER_NORMAL,
gdk_pixbuf_get_pixels (pixbuf), gdk_pixbuf_get_rowstride (pixbuf));
else
gdk_draw_pixbuf (*pixmap_return, gc, pixbuf,
0, 0, 0, 0,
gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf),
GDK_RGB_DITHER_NORMAL,
0, 0);
}
if (mask_return)
{
if (gdk_pixbuf_get_has_alpha (pixbuf))
{
*mask_return = gdk_pixmap_new (gdk_screen_get_root_window (screen),
gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf), 1);
gdk_pixbuf_render_threshold_alpha (pixbuf, *mask_return,
0, 0, 0, 0,
gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf),
alpha_threshold);
}
else
*mask_return = NULL;
}
}
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