added concrete screensaver

RectSaver.cpp

@@ -0,0 +1,24 @@
+//
+// RectSaver.cpp
+// screensaver
+//
+// Created by Bob Polis at 2020-10-26
+// Copyright (c) 2020 SwiftCoder. All rights reserved.
+//
+
+#include "RectSaver.hpp"
+
+RectSaver::RectSaver(cairo_t* context, const cairo_rectangle_t& rect) : ScreensaverPlugin {context, rect} {
+    make_black();
+}
+
+void RectSaver::draw_frame() {
+    cairo_set_source_rgb(_c, random01(), random01(), random01());
+    cairo_rectangle_t rect {random_rect()};
+    cairo_rectangle(_c, rect.x, rect.y, rect.width, rect.height);
+    cairo_fill(_c);
+}
+
+int RectSaver::fps() const {
+    return 5;
+}

RectSaver.hpp

@@ -0,0 +1,23 @@
+//
+// RectSaver.hpp
+// screensaver
+//
+// Created by Bob Polis at 2020-10-26
+// Copyright (c) 2020 SwiftCoder. All rights reserved.
+//
+
+#ifndef _RectSaver_H_
+#define _RectSaver_H_
+
+#include "ScreensaverPlugin.hpp"
+
+class RectSaver : public ScreensaverPlugin {
+    public:
+        RectSaver(cairo_t* context, const cairo_rectangle_t& rect);
+        ~RectSaver() = default;
+
+        void draw_frame() override;
+        int fps() const override;
+};
+
+#endif // _RectSaver_H_