298 lines
9.4 KiB
C
298 lines
9.4 KiB
C
/* GdkPixbuf library - Rendering functions
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*
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* Copyright (C) 1999 The Free Software Foundation
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*
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* Author: Federico Mena-Quintero <federico@gimp.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <gdk/gdk.h>
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#include <gdk-pixbuf/gdk-pixbuf.h>
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#include "gdkpixbuf.h"
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#include "gdkscreen.h"
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#include "gdkinternals.h"
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/**
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* gdk_pixbuf_render_threshold_alpha:
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* @pixbuf: A pixbuf.
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* @bitmap: Bitmap where the bilevel mask will be painted to.
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* @src_x: Source X coordinate.
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* @src_y: source Y coordinate.
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* @dest_x: Destination X coordinate.
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* @dest_y: Destination Y coordinate.
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* @width: Width of region to threshold, or -1 to use pixbuf width
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* @height: Height of region to threshold, or -1 to use pixbuf height
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* @alpha_threshold: Opacity values below this will be painted as zero; all
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* other values will be painted as one.
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*
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* Takes the opacity values in a rectangular portion of a pixbuf and thresholds
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* them to produce a bi-level alpha mask that can be used as a clipping mask for
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* a drawable.
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*
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**/
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void
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gdk_pixbuf_render_threshold_alpha (GdkPixbuf *pixbuf,
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GdkBitmap *bitmap,
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int src_x,
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int src_y,
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int dest_x,
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int dest_y,
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int width,
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int height,
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int alpha_threshold)
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{
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cairo_t *cr;
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int x, y;
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guchar *p;
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int start, start_status;
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int status;
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g_return_if_fail (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB);
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g_return_if_fail (gdk_pixbuf_get_n_channels (pixbuf) == 3 ||
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gdk_pixbuf_get_n_channels (pixbuf) == 4);
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g_return_if_fail (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8);
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if (width == -1)
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width = gdk_pixbuf_get_width (pixbuf);
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if (height == -1)
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height = gdk_pixbuf_get_height (pixbuf);
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g_return_if_fail (bitmap != NULL);
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g_return_if_fail (width >= 0 && height >= 0);
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g_return_if_fail (src_x >= 0 && src_x + width <= gdk_pixbuf_get_width (pixbuf));
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g_return_if_fail (src_y >= 0 && src_y + height <= gdk_pixbuf_get_height (pixbuf));
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g_return_if_fail (alpha_threshold >= 0 && alpha_threshold <= 255);
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if (width == 0 || height == 0)
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return;
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cr = gdk_cairo_create (bitmap);
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cairo_rectangle (cr, dest_x, dest_y, width, height);
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cairo_clip (cr);
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if (!gdk_pixbuf_get_has_alpha (pixbuf))
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{
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cairo_set_source_rgba (cr, 0, 0, 0, alpha_threshold == 255 ? 0 : 1);
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cairo_paint (cr);
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cairo_destroy (cr);
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return;
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}
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cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
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cairo_paint (cr);
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cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
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if (alpha_threshold == 128)
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{
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gdk_cairo_set_source_pixbuf (cr, pixbuf, src_x - dest_x, src_y - dest_y);
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cairo_paint (cr);
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cairo_destroy (cr);
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return;
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}
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cairo_set_source_rgb (cr, 0, 0, 0);
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for (y = 0; y < height; y++)
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{
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p = (gdk_pixbuf_get_pixels (pixbuf) + (y + src_y) * gdk_pixbuf_get_rowstride (pixbuf) + src_x * gdk_pixbuf_get_n_channels (pixbuf)
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+ gdk_pixbuf_get_n_channels (pixbuf) - 1);
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start = 0;
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start_status = *p < alpha_threshold;
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for (x = 0; x < width; x++)
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{
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status = *p < alpha_threshold;
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if (status != start_status)
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{
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if (!start_status)
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cairo_rectangle (cr,
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start + dest_x, y + dest_y,
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x + dest_x, y + dest_y + 1);
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start = x;
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start_status = status;
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}
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p += gdk_pixbuf_get_n_channels (pixbuf);
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}
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if (!start_status)
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cairo_rectangle (cr,
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start + dest_x, y + dest_y,
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x + dest_x, y + dest_y + 1);
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}
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cairo_fill (cr);
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cairo_destroy (cr);
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}
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/**
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* gdk_pixbuf_render_pixmap_and_mask:
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* @pixbuf: A pixbuf.
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* @pixmap_return: Location to store a pointer to the created pixmap,
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* or %NULL if the pixmap is not needed.
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* @mask_return: Location to store a pointer to the created mask,
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* or %NULL if the mask is not needed.
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* @alpha_threshold: Threshold value for opacity values.
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*
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* Creates a pixmap and a mask bitmap which are returned in the @pixmap_return
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* and @mask_return arguments, respectively, and renders a pixbuf and its
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* corresponding thresholded alpha mask to them. This is merely a convenience
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* function; applications that need to render pixbufs with dither offsets or to
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* given drawables should use Cairo and gdk_pixbuf_render_threshold_alpha().
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*
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* The pixmap that is created is created for the colormap returned
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* by gdk_colormap_get_system(). You normally will want to instead use
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* the actual colormap for a widget, and use
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* gdk_pixbuf_render_pixmap_and_mask_for_colormap().
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*
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* If the pixbuf does not have an alpha channel, then *@mask_return will be set
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* to %NULL.
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**/
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void
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gdk_pixbuf_render_pixmap_and_mask (GdkPixbuf *pixbuf,
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GdkPixmap **pixmap_return,
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GdkBitmap **mask_return,
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int alpha_threshold)
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{
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gdk_pixbuf_render_pixmap_and_mask_for_colormap (pixbuf,
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gdk_colormap_get_system (),
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pixmap_return, mask_return,
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alpha_threshold);
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}
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static void
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remove_alpha_channel (GdkPixbuf *pixbuf)
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{
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unsigned int x, y, width, height, stride;
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unsigned char *data;
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if (!gdk_pixbuf_get_has_alpha (pixbuf))
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return;
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width = gdk_pixbuf_get_width (pixbuf);
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height = gdk_pixbuf_get_height (pixbuf);
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stride = gdk_pixbuf_get_rowstride (pixbuf);
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data = gdk_pixbuf_get_pixels (pixbuf);
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for (y = 0; y < height; y++)
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{
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for (x = 0; x < width; x++)
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{
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data[x * 4 + 3] = 0xFF;
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}
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data += stride;
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}
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}
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/**
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* gdk_pixbuf_render_pixmap_and_mask_for_colormap:
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* @pixbuf: A pixbuf.
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* @colormap: A #GdkColormap
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* @pixmap_return: Location to store a pointer to the created pixmap,
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* or %NULL if the pixmap is not needed.
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* @mask_return: Location to store a pointer to the created mask,
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* or %NULL if the mask is not needed.
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* @alpha_threshold: Threshold value for opacity values.
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*
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* Creates a pixmap and a mask bitmap which are returned in the @pixmap_return
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* and @mask_return arguments, respectively, and renders a pixbuf and its
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* corresponding tresholded alpha mask to them. This is merely a convenience
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* function; applications that need to render pixbufs with dither offsets or to
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* given drawables should use Cairo and gdk_pixbuf_render_threshold_alpha().
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*
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* The pixmap that is created uses the #GdkColormap specified by @colormap.
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* This colormap must match the colormap of the window where the pixmap
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* will eventually be used or an error will result.
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*
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* If the pixbuf does not have an alpha channel, then *@mask_return will be set
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* to %NULL.
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**/
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void
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gdk_pixbuf_render_pixmap_and_mask_for_colormap (GdkPixbuf *pixbuf,
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GdkColormap *colormap,
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GdkPixmap **pixmap_return,
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GdkBitmap **mask_return,
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int alpha_threshold)
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{
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GdkScreen *screen;
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g_return_if_fail (GDK_IS_PIXBUF (pixbuf));
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g_return_if_fail (GDK_IS_COLORMAP (colormap));
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screen = gdk_colormap_get_screen (colormap);
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if (pixmap_return)
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{
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GdkPixbuf *tmp_pixbuf;
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cairo_t *cr;
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*pixmap_return = gdk_pixmap_new (gdk_screen_get_root_window (screen),
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gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf),
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gdk_colormap_get_visual (colormap)->depth);
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gdk_drawable_set_colormap (GDK_DRAWABLE (*pixmap_return), colormap);
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/* If the pixbuf has an alpha channel, using gdk_cairo_set_source_pixbuf()
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* would give
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* random pixel values in the area that are within the mask, but semi-
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* transparent. So we treat the pixbuf like a pixbuf without alpha channel;
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* see bug #487865.
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*/
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if (gdk_pixbuf_get_has_alpha (pixbuf))
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{
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int width, height;
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width = gdk_pixbuf_get_width (pixbuf);
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height = gdk_pixbuf_get_height (pixbuf);
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tmp_pixbuf = gdk_pixbuf_copy (pixbuf);
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remove_alpha_channel (tmp_pixbuf);
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}
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else
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tmp_pixbuf = g_object_ref (pixbuf);
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cr = gdk_cairo_create (*pixmap_return);
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gdk_cairo_set_source_pixbuf (cr, pixbuf, 0, 0);
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cairo_paint (cr);
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cairo_destroy (cr);
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g_object_unref (tmp_pixbuf);
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}
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if (mask_return)
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{
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if (gdk_pixbuf_get_has_alpha (pixbuf))
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{
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*mask_return = gdk_pixmap_new (gdk_screen_get_root_window (screen),
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gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf), 1);
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gdk_pixbuf_render_threshold_alpha (pixbuf, *mask_return,
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0, 0, 0, 0,
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gdk_pixbuf_get_width (pixbuf), gdk_pixbuf_get_height (pixbuf),
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alpha_threshold);
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}
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else
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*mask_return = NULL;
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}
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}
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