Several improvements

- Make all random functions const
- Remove make_black() call from setup()
- Add optional size_changed() override

src/ScreensaverPlugin.cpp

@@ -1,10 +1,10 @@
 #include "ScreensaverPlugin.hpp"
+#include <cairo/cairo.h>
 #include <libscnumerics.hpp>
 
 void ScreensaverPlugin::setup(cairo_t* context, const cairo_rectangle_t& rect) {
     _c = context;
     _r = rect;
-    make_black();
 }
 
 int ScreensaverPlugin::fps() const {
@@ -17,11 +17,11 @@ void ScreensaverPlugin::make_black() {
     cairo_fill(_c);
 }
 
-cairo_rectangle_t ScreensaverPlugin::random_rect() {
+cairo_rectangle_t ScreensaverPlugin::random_rect() const {
     return random_rect_in_rect(_r);
 }
 
-cairo_rectangle_t ScreensaverPlugin::random_rect_in_rect(const cairo_rectangle_t& rect) {
+cairo_rectangle_t ScreensaverPlugin::random_rect_in_rect(const cairo_rectangle_t& rect) const {
     cairo_rectangle_t r;
     std::uniform_real_distribution<double> dx {rect.x, rect.width};
     std::uniform_real_distribution<double> dy {rect.y, rect.height};
@@ -47,22 +47,26 @@ cairo_rectangle_t ScreensaverPlugin::random_rect_in_rect(const cairo_rectangle_t
     return r;
 }
 
-double ScreensaverPlugin::random_x() {
+bool ScreensaverPlugin::random_bool() const {
+    return sc::random::boolean();
+}
+
+double ScreensaverPlugin::random_x() const {
     std::uniform_real_distribution<double> dist {0, _r.width};
     return dist(sc::random::instance().engine());
 }
 
-double ScreensaverPlugin::random_y() {
+double ScreensaverPlugin::random_y() const {
     std::uniform_real_distribution<double> dist {0, _r.height};
     return dist(sc::random::instance().engine());
 }
 
-double ScreensaverPlugin::random01() {
+double ScreensaverPlugin::random01() const {
     std::uniform_real_distribution<double> dist {};
     return dist(sc::random::instance().engine());
 }
 
-double ScreensaverPlugin::random_between(double v1, double v2) {
+double ScreensaverPlugin::random_between(double v1, double v2) const {
     std::uniform_real_distribution<double> dist {v1, v2};
     return dist(sc::random::instance().engine());
 }
@@ -100,3 +104,7 @@ void ScreensaverPlugin::config(nlohmann::json&& data) {
 void ScreensaverPlugin::configure() {
     // empty default implementation
 }
+
+void ScreensaverPlugin::size_changed() {
+    // empty default implementation
+}

src/ScreensaverPlugin.hpp

@@ -11,6 +11,7 @@ class ScreensaverPlugin {
 
         virtual void setup(cairo_t* context, const cairo_rectangle_t& rect);
         virtual void configure();
+        virtual void size_changed();
         virtual int fps() const;
 
         virtual std::string version() const = 0;
@@ -27,12 +28,13 @@ class ScreensaverPlugin {
         nlohmann::json _j {};
 
         void make_black();
-        cairo_rectangle_t random_rect();
-        cairo_rectangle_t random_rect_in_rect(const cairo_rectangle_t& rect);
-        double random_x();
-        double random_y();
-        double random01();
-        double random_between(double v1, double v2);
+        cairo_rectangle_t random_rect() const;
+        cairo_rectangle_t random_rect_in_rect(const cairo_rectangle_t& rect) const;
+        bool random_bool() const;
+        double random_x() const;
+        double random_y() const;
+        double random01() const;
+        double random_between(double v1, double v2) const;
         void rounded_rect(const cairo_rectangle_t& rect, double radius);
 };