1 files changed, 99 insertions, 0 deletions
diff --git a/src/fadable.vala b/src/fadable.vala
new file mode 100644
index 0000000..a67ad63
--- /dev/null
+++ b/src/fadable.vala
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+/* -*- Mode: Vala; indent-tabs-mode: nil; tab-width: 4 -*-
+ *
+ * Copyright (C) 2012 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Michael Terry <michael.terry@canonical.com>
+ */
+
+public class FadeTracker : Object
+{
+    public signal void done ();
+
+    public double alpha { get; set; default = 1.0; }
+    public Gtk.Widget widget { get; construct; }
+
+    public enum Mode
+    {
+        FADE_IN,
+        FADE_OUT,
+    }
+
+    public FadeTracker (Gtk.Widget widget)
+    {
+        Object (widget: widget);
+    }
+
+    public void reset (Mode mode)
+    {
+        this.mode = mode;
+        animate_cb (0.0);
+        widget.show ();
+        timer.reset ();
+    }
+
+    private AnimateTimer timer;
+    private Mode mode;
+
+    construct
+    {
+        timer = new AnimateTimer (AnimateTimer.ease_out_quint, AnimateTimer.INSTANT);
+        timer.animate.connect (animate_cb);
+    }
+
+    private void animate_cb (double progress)
+    {
+        if (mode == Mode.FADE_IN)
+        {
+            alpha = progress;
+            if (progress == 1.0)
+            {
+                done ();
+            }
+        }
+        else
+        {
+            alpha = 1.0 - progress;
+            if (progress == 1.0)
+            {
+                widget.hide (); /* finish the job */
+                done ();
+            }
+        }
+
+        widget.queue_draw ();
+    }
+}
+
+public interface Fadable : Gtk.Widget
+{
+    protected abstract FadeTracker fade_tracker { get; protected set; }
+
+    public void fade_in ()
+    {
+        fade_tracker.reset (FadeTracker.Mode.FADE_IN);
+    }
+
+    public void fade_out ()
+    {
+        fade_tracker.reset (FadeTracker.Mode.FADE_OUT);
+    }
+
+    /* In case you want to control fade manually */
+    public void set_alpha (double alpha)
+    {
+        fade_tracker.alpha = alpha;
+        queue_draw ();
+    }
+}