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/* $Id$
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 2, 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, write to the Free Software
Foundation, Inc., Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
xfwm4 - (c) 2002-2011 Olivier Fourdan
xfwm4-windowck-plugin - (c) 2013 Cedric leporcq
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <glib.h>
#include <gdk/gdk.h>
#include <gtk/gtk.h>
#include <libxfce4util/libxfce4util.h>
#include "ui_style.h"
static GdkRGBA
shade (const GdkRGBA* color, float b)
{
GdkRGBA rgba;
rgba.red = color->red * b;
rgba.green = color->green * b;
rgba.blue = color->blue * b;
return rgba;
}
static GdkRGBA
mix (const GdkRGBA* color1, const GdkRGBA* color2, float a)
{
GdkRGBA color;
color.red = color1->red * a + color2->red * (1 - a);
color.green = color1->green * a + color2->green * (1 - a);
color.blue = color1->blue * a + color2->blue * (1 - a);
return color;
}
static gchar *
rgba_to_hex_string (const GdkRGBA * rgba)
{
return g_strdup_printf ("#%04x%04x%04x", (guint16)(rgba->red * USHRT_MAX), (guint16)(rgba->green * USHRT_MAX), (guint16)(rgba->blue * USHRT_MAX));
}
gchar *
get_ui_color (GtkWidget *win, GtkStateFlags state)
{
GtkStyleContext *style;
GdkRGBA rgba;
gchar *s;
TRACE ("entering get_ui_color");
g_return_val_if_fail (win != NULL, NULL);
g_return_val_if_fail (GTK_IS_WIDGET (win), NULL);
g_return_val_if_fail (gtk_widget_get_realized (win), NULL);
style = gtk_widget_get_style_context (win);
gtk_style_context_get_color (style, state, &rgba);
s = rgba_to_hex_string (&rgba);
TRACE ("color[%d]=%s", state, s);
return s;
}
/**
* What user sees is a combination of multiple layers.
* This is only important when top layer is semi-transparent.
*
* Adapted from org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java
*/
static void
render_all_backgrounds(GtkStyleContext *style_ctx, cairo_t *cairo)
{
GtkStyleContext *parent_style_ctx = gtk_style_context_get_parent (style_ctx);
if (parent_style_ctx != NULL)
render_all_backgrounds (parent_style_ctx, cairo);
gtk_render_background (style_ctx, cairo, -50, -50, 100, 100);
}
/**
* Calculates original color from RGBA with premultiplied alpha.
*
* NOTE: Calculating inverse gives a range of possible colors due to rounding that
* occurs with integer calculations. However, alpha-blend formula only has the
* multiplied component, so all of those inverses are equivalent.
*
* Adapted from org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java
*/
static int
inverse_premultiplied_color(int color, int alpha)
{
if (alpha == 0)
return 0;
return (255*color + alpha-1) / alpha;
}
/**
* Background in GTK theme can be more complex then just solid color:
* 1) Due to 'background-image', 'background-position', 'background-repeat', etc.
* Example: 'tooltip' in 'Ambiance' theme uses 'background-image'.
* 2) If background is semi-transparent, user actually sees a combination of layers.
* Example: 'tooltip' in 'HighContrast' theme has transparent label.
* Both problems are solved by drawing to a temporary image and getting
* the color of the pixel in the middle.
*
* Adapted from org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java
*/
static GdkRGBA
style_context_estimate_background_color(GtkStyleContext *context, GtkStateFlags state)
{
cairo_surface_t *surface;
cairo_t *cairo;
unsigned char *data;
int a, r, g, b;
GdkRGBA rgba;
// Render to a temporary image
gtk_style_context_save (context);
gtk_style_context_set_state (context, state);
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 1, 1);
cairo = cairo_create (surface);
render_all_backgrounds (context, cairo);
cairo_fill (cairo);
cairo_surface_flush (surface);
data = cairo_image_surface_get_data (surface);
// CAIRO_FORMAT_ARGB32 means a-r-g-b order, 1 byte per value.
a = data[3];
r = data[2];
g = data[1];
b = data[0];
cairo_surface_destroy (surface);
cairo_destroy (cairo);
gtk_style_context_restore (context);
// NOTE: cairo uses premultiplied alpha (see CAIRO_FORMAT_ARGB32)
rgba.alpha = a / 255.0;
rgba.red = inverse_premultiplied_color(r, a) / 255.0;
rgba.green = inverse_premultiplied_color(g, a) / 255.0;
rgba.blue = inverse_premultiplied_color(b, a) / 255.0;
return rgba;
}
gchar *
mix_bg_fg (GtkWidget * win, GtkStateFlags state, float alpha, float beta)
{
GtkStyleContext *style;
GdkRGBA fg_rgba;
GdkRGBA bg_rgba;
GdkRGBA rgba;
gchar *s;
TRACE ("entering mix_bg_fg");
g_return_val_if_fail (win != NULL, NULL);
g_return_val_if_fail (GTK_IS_WIDGET (win), NULL);
g_return_val_if_fail (gtk_widget_get_realized (win), NULL);
style = gtk_widget_get_style_context (win);
gtk_style_context_get_color (style, state, &fg_rgba);
bg_rgba = style_context_estimate_background_color (style, state);
rgba = mix (&fg_rgba, &bg_rgba, alpha);
rgba = shade (&rgba, beta);
s = rgba_to_hex_string (&rgba);
TRACE ("mix_bg_fg[%d]=%s", state, s);
return s;
}
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