sdgui: make an attempt at smooth scrolling

src/sdgui.c

@@ -195,15 +195,9 @@ on_key_press (G_GNUC_UNUSED GtkWidget *widget, GdkEvent *event,
 		// Can't use gtk_widget_add_accelerator() to change-current-page(-1/+1)
 		// because that signal has arguments, which cannot be passed.
 		if (event->key.keyval == GDK_KEY_Page_Up)
-		{
-			gtk_notebook_prev_page (GTK_NOTEBOOK (g.notebook));
-			return TRUE;
-		}
+			return gtk_notebook_prev_page (GTK_NOTEBOOK (g.notebook)), TRUE;
 		if (event->key.keyval == GDK_KEY_Page_Down)
-		{
-			gtk_notebook_next_page (GTK_NOTEBOOK (g.notebook));
-			return TRUE;
-		}
+			return gtk_notebook_next_page (GTK_NOTEBOOK (g.notebook)), TRUE;
 	}
 	if (mods == GDK_MOD1_MASK)
 	{
@@ -216,6 +210,14 @@ on_key_press (G_GNUC_UNUSED GtkWidget *widget, GdkEvent *event,
 			return TRUE;
 		}
 	}
+	if (mods == 0)
+	{
+		StardictView *view = STARDICT_VIEW (g.view);
+		if (event->key.keyval == GDK_KEY_Page_Up)
+			return stardict_view_scroll (view, GTK_SCROLL_PAGES, -0.5), TRUE;
+		if (event->key.keyval == GDK_KEY_Page_Down)
+			return stardict_view_scroll (view, GTK_SCROLL_PAGES, +0.5), TRUE;
+	}
 	return FALSE;
 }
 
@@ -341,8 +343,6 @@ main (int argc, char *argv[])
 	// TODO: make the entry have a background colour, rather than transparency
 	gtk_entry_set_has_frame (GTK_ENTRY (g.entry), FALSE);
 
-	// TODO: supposedly attach to "key-press-event" here and react to
-	// PageUp/PageDown and up/down arrow keys... either here or in the Entry
 	g.window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
 	gtk_window_set_default_size (GTK_WINDOW (g.window), 300, 600);
 	g_signal_connect (g.window, "destroy",

src/stardict-view.c

@@ -395,8 +395,9 @@ stardict_view_realize (GtkWidget *widget)
 		// Input-only would presumably also work (as in GtkPathBar, e.g.),
 		// but it merely seems to involve more work.
 		.wclass      = GDK_INPUT_OUTPUT,
-
 		.visual      = gtk_widget_get_visual (widget),
+
+		// GDK_SMOOTH_SCROLL_MASK is useless, will stop sending UP/DOWN
 		.event_mask  = gtk_widget_get_events (widget) | GDK_SCROLL_MASK,
 	};
 
@@ -481,15 +482,16 @@ stardict_view_scroll_event (GtkWidget *widget, GdkEventScroll *event)
 	switch (event->direction)
 	{
 	case GDK_SCROLL_UP:
-		self->top_offset -= 3 * natural_row_size (widget);
-		adjust_for_offset (self);
+		stardict_view_scroll (self, GTK_SCROLL_STEPS, -3);
 		return TRUE;
 	case GDK_SCROLL_DOWN:
-		self->top_offset += 3 * natural_row_size (widget);
+		stardict_view_scroll (self, GTK_SCROLL_STEPS, +3);
+		return TRUE;
+	case GDK_SCROLL_SMOOTH:
+		self->top_offset += event->delta_y;
 		adjust_for_offset (self);
 		return TRUE;
 	default:
-		// GDK_SCROLL_SMOOTH doesn't fit the intended way of usage
 		return FALSE;
 	}
 }
@@ -555,3 +557,24 @@ stardict_view_set_matched (StardictView *self, const gchar *matched)
 	self->matched = g_strdup (matched);
 	reload (self);
 }
+
+void
+stardict_view_scroll (StardictView *self, GtkScrollStep step, gdouble amount)
+{
+	g_return_if_fail (STARDICT_IS_VIEW (self));
+
+	GtkWidget *widget = GTK_WIDGET (self);
+	switch (step)
+	{
+	case GTK_SCROLL_STEPS:
+		self->top_offset += amount * natural_row_size (widget);
+		break;
+	case GTK_SCROLL_PAGES:
+		self->top_offset += amount * gtk_widget_get_allocated_height (widget);
+		break;
+	default:
+		break;
+	}
+
+	adjust_for_offset (self);
+}

src/stardict-view.h

@@ -30,5 +30,7 @@ GtkWidget *stardict_view_new (void);
 void stardict_view_set_position (StardictView *view,
 	StardictDict *dict, guint position);
 void stardict_view_set_matched (StardictView *view, const gchar *matched);
+void stardict_view_scroll (StardictView *view,
+	GtkScrollStep step, gdouble amount);
 
 #endif  // ! STARDICT_VIEW_H