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conky/lua/libcairo_imlib2_helper.h

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/* -*- mode: c; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: t -*-
*
* Conky, a system monitor, based on torsmo
*
* Please see COPYING for details
*
* Copyright (c) 2005-2012 Brenden Matthews, Philip Kovacs, et. al.
* (see AUTHORS)
* All rights reserved.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef _LIBCAIRO_IMAGE_HELPER_H_
#define _LIBCAIRO_IMAGE_HELPER_H_
#include <cairo.h>
#include <Imlib2.h>
void
cairo_draw_image(const char * file, cairo_surface_t * cs, int x, int y,
double scale_x, double scale_y,
double * return_scale_w, double * return_scale_h)
{
Imlib_Image * image = imlib_load_image(file);
if (! image) { return; }
imlib_context_set_image(image);
int w = imlib_image_get_width(), h = imlib_image_get_height();
double scaled_w = *return_scale_w = scale_x * (double)w
, scaled_h = *return_scale_h = scale_y * (double)h;
/* create temporary image */
Imlib_Image premul = imlib_create_image(scaled_w, scaled_h);
/* FIXME: add error handling */
/* fill with opaque black */
imlib_context_set_image(premul);
imlib_context_set_color(0, 0, 0, 255);
imlib_image_fill_rectangle(0, 0, scaled_w, scaled_h);
/* blend source image on top -
* in effect this multiplies the rgb values by alpha */
imlib_blend_image_onto_image(image, 0, 0, 0, w, h, 0, 0, scaled_w, scaled_h);
/* and use the alpha channel of the source image */
imlib_image_copy_alpha_to_image(image, 0, 0);
/* now pass the result to cairo */
cairo_surface_t * result = cairo_image_surface_create_for_data(
(void *) imlib_image_get_data_for_reading_only(),
CAIRO_FORMAT_ARGB32, scaled_w, scaled_h, sizeof(DATA32) * scaled_w);
cairo_t * cr = cairo_create(cs);
cairo_set_source_surface(cr, result, x, y);
cairo_paint(cr);
imlib_context_set_image(image);
imlib_free_image();
imlib_context_set_image(premul);
imlib_free_image();
cairo_destroy(cr);
cairo_surface_destroy(result);
}
#endif /* _LIBCAIRO_IMAGE_HELPER_H_ */