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// Copyright 2005-6 Ben Hutchings <ben@decadent.org.uk>.
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// See the file "COPYING" for licence details.
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#include <gdkmm/pixbuf.h>
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#include "auto_array.hpp"
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// Find pixel differences between an "old" and "new" RGB Pixbuf
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// (or RGBA, but the alpha component will be ignored) and copy the
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// differing pixels from the new one to a third RGBA Pixbuf at the
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// specified offset with full opacity.
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// The width and height of the new Pixbufs must be equal and match
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// the specified dimensions. The width and height of the old and
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// third Pixbuf must be large enough to store a rectangle of
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// those dimensions at the specified offset.
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void diff_rgb_pixbufs(Glib::RefPtr<Gdk::Pixbuf> old_buf,
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Glib::RefPtr<Gdk::Pixbuf> new_buf,
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Glib::RefPtr<Gdk::Pixbuf> diff_buf,
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int offset_x, int offset_y,
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int width, int height)
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assert(old_buf->get_colorspace() == Gdk::COLORSPACE_RGB);
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assert(new_buf->get_colorspace() == Gdk::COLORSPACE_RGB);
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assert(diff_buf->get_colorspace() == Gdk::COLORSPACE_RGB
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&& diff_buf->get_has_alpha());
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int old_bpr = old_buf->get_rowstride();
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int old_bpp = old_buf->get_n_channels();
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assert(old_buf->get_width() >= offset_x + width);
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assert(old_buf->get_height() >= offset_y + height);
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int new_bpr = new_buf->get_rowstride();
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int new_bpp = new_buf->get_n_channels();
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assert(new_buf->get_width() == width);
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assert(new_buf->get_height() == height);
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int diff_bpr = diff_buf->get_rowstride();
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int diff_bpp = diff_buf->get_n_channels();
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assert(diff_bpp == 4);
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assert(diff_buf->get_width() >= offset_x + width);
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assert(diff_buf->get_height() >= offset_y + height);
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const guint8 * old_p = (old_buf->get_pixels()
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+ old_bpp * offset_x);
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const guint8 * new_p = new_buf->get_pixels();
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guint8 * diff_p = (diff_buf->get_pixels()
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+ diff_bpp * offset_x);
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for (int y = 0; y != height; ++y)
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for (int x = 0; x != width; ++x)
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if (old_p[0] != new_p[0]
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|| old_p[1] != new_p[1]
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|| old_p[2] != new_p[2])
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diff_p[3] = 0xFF; // fully opaque
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old_p += old_bpr - old_bpp * width;
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new_p += new_bpr - new_bpp * width;
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diff_p += diff_bpr - diff_bpp * width;
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// Quantise an RGBA Pixbuf to the specified number of colours, including
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// one transparent colour. Currently uses Floyd-Steinberg dithering.
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void quantise_rgba_pixbuf(Glib::RefPtr<Gdk::Pixbuf> buf, int n_colours)
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assert(buf->get_colorspace() == Gdk::COLORSPACE_RGB
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&& buf->get_has_alpha());
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int bpr = buf->get_rowstride();
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assert(buf->get_n_channels() == 4);
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int width = buf->get_width();
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int height = buf->get_height();
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unsigned char * buf_p = buf->get_pixels();
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auto_array<unsigned char *> rows(new unsigned char *[height]);
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for (int y = 0; y != height; ++y)
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rows[y] = &buf_p[y * bpr];
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auto_array<unsigned char> quant_buf_p(
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new unsigned char[width * height]);
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auto_array<unsigned char *> quant_rows(
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new unsigned char *[height]);
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for (int y = 0; y != height; ++y)
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quant_rows[y] = &quant_buf_p[y * width];
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auto_array<unsigned int> colours(new unsigned int[n_colours]);
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quantize(rows.get(), quant_rows.get(), width, height,
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JDITHER_FS, n_colours, colours.get());
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// Pixbuf doesn't support quantised images, so convert back to RGBA.
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for (int y = 0; y != height; ++y)
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for (int x = 0; x != width; ++x)
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unsigned int colour = colours[quant_rows[y][x]];
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rows[y][4*x] = colour;
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rows[y][4*x+1] = colour >> 8;
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rows[y][4*x+2] = colour >> 16;
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rows[y][4*x+3] = colour >> 24;
added
removed
pixbufs.cpp
