mate_desktop_gtk_style_get_light_color and mate_desktop_gtk_style_get_dark_color

2 files changed, 260 insertions, 0 deletions

diff --git a/libmate-desktop/mate-desktop-utils.c b/libmate-desktop/mate-desktop-utils.c
index 431c57f..df7aa3f 100644
--- a/libmate-desktop/mate-desktop-utils.c
+++ b/libmate-desktop/mate-desktop-utils.c
@@ -36,6 +36,23 @@
 
 #include "private.h"
 
+#if GTK_CHECK_VERSION (3, 0, 0)
+static void
+gtk_style_shade (GdkRGBA *a,
+                 GdkRGBA *b,
+                 gdouble  k);
+
+static void
+rgb_to_hls (gdouble *r,
+            gdouble *g,
+            gdouble *b);
+
+static void
+hls_to_rgb (gdouble *h,
+            gdouble *l,
+            gdouble *s);
+#endif
+
 /**
  * mate_desktop_prepend_terminal_to_vector:
  * @argc: a pointer to the vector size
@@ -224,3 +241,234 @@ _mate_desktop_init_i18n (void) {
 	}
 }
 
+
+#if GTK_CHECK_VERSION (3, 0, 0)
+
+/**
+ * Takes a colour "a", scales the lightness and saturation by a certain amount,
+ * and sets "b" to the resulting colour.
+ * gtkstyle.c cut-and-pastage.
+ *
+ * \param a  the starting colour
+ * \param b  [out] the resulting colour
+ * \param k  amount to scale lightness and saturation by
+ */
+static void
+gtk_style_shade (GdkRGBA *a,
+                 GdkRGBA *b,
+                 gdouble  k)
+{
+	gdouble red;
+	gdouble green;
+	gdouble blue;
+
+	red = a->red;
+	green = a->green;
+	blue = a->blue;
+
+	rgb_to_hls (&red, &green, &blue);
+
+	green *= k;
+	if (green > 1.0)
+		green = 1.0;
+	else if (green < 0.0)
+		green = 0.0;
+
+	blue *= k;
+	if (blue > 1.0)
+		blue = 1.0;
+	else if (blue < 0.0)
+		blue = 0.0;
+
+	hls_to_rgb (&red, &green, &blue);
+
+	b->red = red;
+	b->green = green;
+	b->blue = blue;
+}
+
+/**
+ * Converts a red/green/blue triplet to a hue/lightness/saturation triplet.
+ *
+ * \param r  on input, red; on output, hue
+ * \param g  on input, green; on output, lightness
+ * \param b  on input, blue; on output, saturation
+ */
+static void
+rgb_to_hls (gdouble *r,
+            gdouble *g,
+            gdouble *b)
+{
+	gdouble min;
+	gdouble max;
+	gdouble red;
+	gdouble green;
+	gdouble blue;
+	gdouble h, l, s;
+	gdouble delta;
+
+	red = *r;
+	green = *g;
+	blue = *b;
+
+	if (red > green)
+	{
+		if (red > blue)
+			max = red;
+		else
+			max = blue;
+
+		if (green < blue)
+			min = green;
+		else
+			min = blue;
+	}
+	else
+	{
+		if (green > blue)
+			max = green;
+		else
+			max = blue;
+
+		if (red < blue)
+			min = red;
+		else
+			min = blue;
+	}
+
+	l = (max + min) / 2;
+	s = 0;
+	h = 0;
+
+	if (max != min)
+	{
+		if (l <= 0.5)
+			s = (max - min) / (max + min);
+		else
+			s = (max - min) / (2 - max - min);
+
+		delta = max -min;
+		if (red == max)
+			h = (green - blue) / delta;
+		else if (green == max)
+			h = 2 + (blue - red) / delta;
+		else if (blue == max)
+			h = 4 + (red - green) / delta;
+
+		h *= 60;
+		if (h < 0.0)
+			h += 360;
+	}
+
+	*r = h;
+	*g = l;
+	*b = s;
+}
+
+/**
+ * Converts a hue/lightness/saturation triplet to a red/green/blue triplet.
+ *
+ * \param h  on input, hue; on output, red
+ * \param l  on input, lightness; on output, green
+ * \param s  on input, saturation; on output, blue
+ */
+static void
+hls_to_rgb (gdouble *h,
+            gdouble *l,
+            gdouble *s)
+{
+	gdouble hue;
+	gdouble lightness;
+	gdouble saturation;
+	gdouble m1, m2;
+	gdouble r, g, b;
+
+	lightness = *l;
+	saturation = *s;
+
+	if (lightness <= 0.5)
+		m2 = lightness * (1 + saturation);
+	else
+		m2 = lightness + saturation - lightness * saturation;
+	m1 = 2 * lightness - m2;
+
+	if (saturation == 0)
+	{
+		*h = lightness;
+		*l = lightness;
+		*s = lightness;
+	}
+	else
+	{
+		hue = *h + 120;
+		while (hue > 360)
+			hue -= 360;
+		while (hue < 0)
+			hue += 360;
+
+		if (hue < 60)
+			r = m1 + (m2 - m1) * hue / 60;
+		else if (hue < 180)
+			r = m2;
+		else if (hue < 240)
+			r = m1 + (m2 - m1) * (240 - hue) / 60;
+		else
+			r = m1;
+
+		hue = *h;
+		while (hue > 360)
+			hue -= 360;
+		while (hue < 0)
+			hue += 360;
+
+		if (hue < 60)
+			g = m1 + (m2 - m1) * hue / 60;
+		else if (hue < 180)
+			g = m2;
+		else if (hue < 240)
+			g = m1 + (m2 - m1) * (240 - hue) / 60;
+		else
+			g = m1;
+
+		hue = *h - 120;
+		while (hue > 360)
+			hue -= 360;
+		while (hue < 0)
+			hue += 360;
+
+		if (hue < 60)
+			b = m1 + (m2 - m1) * hue / 60;
+		else if (hue < 180)
+			b = m2;
+		else if (hue < 240)
+			b = m1 + (m2 - m1) * (240 - hue) / 60;
+		else
+			b = m1;
+
+		*h = r;
+		*l = g;
+		*s = b;
+	}
+}
+
+/* Based on set_color() in gtkstyle.c */
+#define LIGHTNESS_MULT 1.3
+#define DARKNESS_MULT  0.7
+void
+mate_desktop_gtk_style_get_light_color (GtkStyleContext *style,
+                                        GtkStateFlags    state,
+                                        GdkRGBA         *color)
+{
+	gtk_style_context_get_background_color (style, state, color);
+	gtk_style_shade (color, color, LIGHTNESS_MULT);
+}
+
+void
+mate_desktop_gtk_style_get_dark_color (GtkStyleContext *style,
+                                       GtkStateFlags    state,
+                                       GdkRGBA         *color)
+{
+	gtk_style_context_get_background_color (style, state, color);
+	gtk_style_shade (color, color, DARKNESS_MULT);
+}
+#endif
diff --git a/libmate-desktop/mate-desktop-utils.h b/libmate-desktop/mate-desktop-utils.h
index 824b11a..972e0e9 100644
--- a/libmate-desktop/mate-desktop-utils.h
+++ b/libmate-desktop/mate-desktop-utils.h
@@ -42,6 +42,18 @@ void mate_desktop_prepend_terminal_to_vector (int *argc, char ***argv);
 /* replace gdk_spawn_command_line_on_screen, not available in GTK3 */
 gboolean mate_gdk_spawn_command_line_on_screen (GdkScreen *screen, const gchar *command, GError **error);
 
+#if GTK_CHECK_VERSION (3, 0, 0)
+void
+mate_desktop_gtk_style_get_light_color (GtkStyleContext *style,
+                                        GtkStateFlags    state,
+                                        GdkRGBA         *color);
+
+void
+mate_desktop_gtk_style_get_dark_color (GtkStyleContext *style,
+                                       GtkStateFlags    state,
+                                       GdkRGBA         *color);
+#endif
+
 G_END_DECLS
 
 #endif /* MATE_DESKTOP_UTILS_H */