GTK API deprecation: use GtkCssProvider for window background.

gdk_window_set_background_rgba is deprecated as of GTK 3.22, because
apparently you can't just _say_ any more 'here is what I want my
window's background colour to be in places where a widget isn't'.
Instead you have to provide a GtkStyleProvider which can be slotted
into a wobbly tower of other providers with associated priorities, so
that the user can override your choices if they really want to.

And the easiest way to constructc a GtkStyleProvider in turn is to
write *actual CSS* and get GTK to parse it, so I end up converting my
nice numeric RGB values into a complicated text format for another
part of _the same process_ to parse back into numbers. Sigh.

diff --git a/gtk.c b/gtk.c
index 53f5d2201b12577a8b65c5d4a0c2f8dbea5b3d29..bf585d6cbb1a869686a4d57c472eb14354735dc6 100644 (file)
--- a/gtk.c
+++ b/gtk.c
@@ -144,6 +144,9 @@ struct frontend {
     GtkWidget *area;
     GtkWidget *statusbar;
     GtkWidget *menubar;
+#if GTK_CHECK_VERSION(3,20,0)
+    GtkCssProvider *css_provider;
+#endif
     guint statusctx;
     int w, h;
     midend *me;
@@ -290,7 +293,27 @@ static void set_colour(frontend *fe, int colour)
 
 static void set_window_background(frontend *fe, int colour)
 {
-#if GTK_CHECK_VERSION(3,0,0)
+#if GTK_CHECK_VERSION(3,20,0)
+    char css_buf[512];
+    sprintf(css_buf, ".background { "
+            "background-color: #%02x%02x%02x; }",
+            (unsigned)(fe->colours[3*colour + 0] * 255),
+            (unsigned)(fe->colours[3*colour + 1] * 255),
+            (unsigned)(fe->colours[3*colour + 2] * 255));
+    if (!fe->css_provider)
+        fe->css_provider = gtk_css_provider_new();
+    if (!gtk_css_provider_load_from_data(
+            GTK_CSS_PROVIDER(fe->css_provider), css_buf, -1, NULL))
+        assert(0 && "Couldn't load CSS");
+    gtk_style_context_add_provider(
+        gtk_widget_get_style_context(fe->window),
+        GTK_STYLE_PROVIDER(fe->css_provider),
+        GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+    gtk_style_context_add_provider(
+        gtk_widget_get_style_context(fe->area),
+        GTK_STYLE_PROVIDER(fe->css_provider),
+        GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+#elif GTK_CHECK_VERSION(3,0,0)
     GdkRGBA rgba;
     rgba.red = fe->colours[3*colour + 0];
     rgba.green = fe->colours[3*colour + 1];
@@ -2355,6 +2378,9 @@ static frontend *new_window(char *arg, int argtype, char **error)
     extern const int n_xpm_icons;
 
     fe = snew(frontend);
+#if GTK_CHECK_VERSION(3,20,0)
+    fe->css_provider = NULL;
+#endif
 
     fe->timer_active = FALSE;
     fe->timer_id = -1;