labwc/src/common/graphic-helpers.c

// SPDX-License-Identifier: GPL-2.0-only

#include <cairo.h>
#include <wlr/types/wlr_scene.h>
#include "common/graphic-helpers.h"

/* Draws a border with a specified line width */
void
draw_cairo_border(cairo_t *cairo, struct wlr_fbox fbox, double line_width)
{
	cairo_save(cairo);

	/* The anchor point of a line is in the center */
	fbox.x += line_width / 2.0;
	fbox.y += line_width / 2.0;
	fbox.width -= line_width;
	fbox.height -= line_width;
	cairo_set_line_width(cairo, line_width);
	cairo_rectangle(cairo, fbox.x, fbox.y, fbox.width, fbox.height);
	cairo_stroke(cairo);

	cairo_restore(cairo);
}

/* Sets the cairo color. Splits the single color channels */
void
set_cairo_color(cairo_t *cairo, const float *c)
{
	/*
	 * We are dealing with pre-multiplied colors
	 * but cairo expects unmultiplied colors here
	 */
	float alpha = c[3];

	if (alpha == 0.0f) {
		cairo_set_source_rgba(cairo, 0, 0, 0, 0);
		return;
	}

	cairo_set_source_rgba(cairo, c[0] / alpha, c[1] / alpha,
		c[2] / alpha, alpha);
}