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conky/lua/libcairo_imlib2_helper.h
2021-02-27 09:14:19 -06:00

84 lines
2.6 KiB
C

/*
*
* Conky, a system monitor, based on torsmo
*
* Please see COPYING for details
*
* Copyright (c) 2005-2021 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 <Imlib2.h>
#include <cairo.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) {
int w, h;
double scaled_w, scaled_h;
Imlib_Image premul;
cairo_surface_t *result;
cairo_t *cr;
Imlib_Image *image = imlib_load_image(file);
if (!image) { return; }
imlib_context_set_image(image);
w = imlib_image_get_width();
h = imlib_image_get_height();
scaled_w = *return_scale_w = scale_x * (double)w;
scaled_h = *return_scale_h = scale_y * (double)h;
/* create temporary 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 */
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);
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_ */