Use transparency for the fill color

And use random_between() function

modules/FadingRects/FadingRects.cpp

@@ -2,7 +2,6 @@
 #include <cairo/cairo.h>
 #include <libscscreensaver.hpp>
 #include <libsccolor.hpp>
-#include <libscnumerics.hpp>
 #include <vector>
 #include <algorithm>
 
@@ -36,7 +35,7 @@ class FadingRects : public ScreensaverPlugin {
         FadingRects() = default;
         ~FadingRects() = default;
 
-        void setup(cairo_t* context, const cairo_rectangle_t& rect) override;
+        void configure() override;
         int fps() const override;
         void update () override;
         void render() override;
@@ -55,7 +54,7 @@ ScreensaverPlugin* create_instance() {
 }
 
 std::string FadingRects::version() const {
-    return "1.2.0";
+    return "1.2.1";
 }
 
 int FadingRects::fps() const {
@@ -151,8 +150,7 @@ Color FadingRects::next_color() {
     return Color {hsb};
 }
 
-void FadingRects::setup(cairo_t* context, const cairo_rectangle_t& rect) {
-    ScreensaverPlugin::setup(context, rect);
-    _hue = sc::random::double_between(0.0, 360.0);
+void FadingRects::configure() {
+    _hue = random_between(0.0, 360.0);
     _rects.clear();
 }

modules/FadingRects/premake.make

@@ -1,4 +1,4 @@
-LDLIBS := -lcairo -lscscreensaver -lscnumerics -lsccolor
+LDLIBS := -lcairo -lscscreensaver -lsccolor
 UNAME_S := $(shell uname -s)
 PROJ := $(shell basename $$(pwd))
 PLUGIN := $(PROJ).saver

modules/Polygon/Makefile

@@ -0,0 +1,53 @@
+include premake.make
+
+# some important install locations
+PREFIX ?= /usr/local
+DATADIR ?= $(PREFIX)/share
+INSTALLDIR ?= $(DATADIR)/$(INSTALLDIRNAME)
+
+SRCS := $(wildcard *.cpp)
+OBJS := $(SRCS:.cpp=.o)
+DEPS := $(SRCS:.cpp=.dep)
+
+CXX ?= g++
+
+CXXFLAGS += -Wshadow -Wall -Wpedantic -Wextra -Wno-unused-parameter
+CXXFLAGS += -g3 -std=c++20 -fPIC
+ifeq ($(DEBUG),1)
+	CXXFLAGS += -D DEBUG -O0
+else
+	CXXFLAGS += -D NDEBUG -O3
+endif
+
+%.o: %.cpp
+	$(CXX) $(CXXFLAGS) -o $@ -MMD -MP -MT $@ -MF $*.dep -c $<
+
+%.dep: ;
+
+.PHONY: all clean install uninstall
+
+all: $(PLUGIN)
+
+$(PLUGIN): $(OBJS)
+ifeq ($(UNAME_S),Darwin)
+	$(CXX) -g3 -dynamiclib -o $(PLUGIN) $(LDFLAGS) $(OBJS) $(LDLIBS)
+else
+	$(CXX) -g3 -shared -o $(PLUGIN) $(LDFLAGS) $(OBJS) $(LDLIBS)
+endif
+
+-include $(DEPS)
+
+clean:
+	rm -f $(OBJS) $(DEPS) $(PLUGIN)
+
+$(INSTALLDIR):
+	install -m 0755 -d $@
+
+install: $(INSTALLDIR)
+	install -m 0644 $(PLUGIN) $(INSTALLDIR)
+ifdef EXTRAFILES
+	install -m 0644 $(EXTRAFILES) $(INSTALLDIR)
+endif
+
+uninstall:
+	rm -f $(INSTALLDIR)/$(PLUGIN) $(addprefix $(INSTALLDIR)/, $(EXTRAFILES))

modules/Polygon/Polygon.cpp

@@ -0,0 +1,107 @@
+#include "Polygon.hpp"
+#include <cairo/cairo.h>
+#include <libsccolor.hpp>
+#include <libscscreensaver.hpp>
+#include <vector>
+
+struct Point {
+    double x;
+    double y;
+    double speed_x;
+    double speed_y;
+};
+
+class Polygon : public ScreensaverPlugin {
+public:
+    Polygon() = default;
+    ~Polygon() = default;
+
+    void configure() override;
+    void update() override;
+    void render() override;
+    std::string version() const override;
+    void size_changed() override;
+
+private:
+    int _num_points {};
+    double _min_speed {0.2};
+    double _max_speed {2.0};
+    double _stroke_width {1.0};
+    Color _color {"#FFFFFF"};
+    std::vector<Point> _points;
+    double _hue;
+};
+
+ScreensaverPlugin *create_instance() { return new Polygon; }
+
+void Polygon::configure() {
+    _num_points = _j["num-points"];
+    _min_speed = _j["min-speed"];
+    _max_speed = _j["max-speed"];
+    _stroke_width = _j["stroke-width"];
+    for (int i = 0; i < _num_points; ++i) {
+        Point p;
+        p.x = random_x();
+        p.y = random_y();
+        p.speed_x = random_between(_min_speed, _max_speed);
+        p.speed_x *= random_bool() ? 1 : -1;
+        p.speed_y = random_between(_min_speed, _max_speed);
+        p.speed_y *= random_bool() ? 1 : -1;
+        _points.push_back(p);
+    }
+    _hue = random_between(0.0, 360.0);
+}
+
+void Polygon::size_changed() {
+    for (Point &p : _points) {
+        p.x = random_x();
+        p.y = random_y();
+    }
+}
+
+std::string Polygon::version() const { return "1.1.0"; }
+
+void Polygon::update() {
+    // update points
+    for (Point& p : _points) {
+        p.x += p.speed_x;
+        if (p.x < 0 || p.x > _r.width) {
+            p.speed_x *= -1;
+            p.x += p.speed_x;
+        }
+        p.y += p.speed_y;
+        if (p.y < 0 || p.y > _r.height) {
+            p.speed_y *= -1;
+            p.y += p.speed_y;
+        }
+    }
+    // update hue
+    _hue += 0.5;
+    if (_hue >= 360.0) {
+        _hue -= 360.0;
+    }
+    // construct color
+    HSB hsb;
+    hsb.h = _hue;
+    hsb.s = 1.0;
+    hsb.b = 0.7;
+    _color = hsb;
+}
+
+void Polygon::render() {
+    make_black();
+    Point first = _points[0];
+    cairo_new_path(_c);
+    cairo_move_to(_c, first.x, first.y);
+    for (size_t i = 1; i < _points.size(); ++i) {
+        Point& p = _points[i];
+        cairo_line_to(_c, p.x, p.y);
+    }
+    cairo_close_path(_c);
+    RGB c = RGB(_color);
+    cairo_set_source_rgb(_c, c.r, c.g, c.b);
+    cairo_set_line_width(_c, _stroke_width);
+    cairo_stroke_preserve(_c);
+    cairo_set_source_rgba(_c, c.r, c.g, c.b, 0.2);
+    cairo_fill(_c);
+}

modules/Polygon/Polygon.hpp

@@ -0,0 +1,10 @@
+#ifndef _Polygon_H_
+#define _Polygon_H_
+
+class ScreensaverPlugin;
+
+extern "C" {
+    ScreensaverPlugin* create_instance();
+}
+
+#endif // _Polygon_H_

modules/Polygon/Polygon.json

@@ -0,0 +1,6 @@
+{
+    "num-points": 11,
+    "min-speed": 0.2,
+    "max-speed": 2.0,
+    "stroke-width": 2.0
+}

modules/Polygon/premake.make

@@ -0,0 +1,6 @@
+LDLIBS := -lcairo -lscscreensaver -lsccolor
+UNAME_S := $(shell uname -s)
+PROJ := $(shell basename $$(pwd))
+PLUGIN := $(PROJ).saver
+INSTALLDIRNAME := screensaver/plugins
+EXTRAFILES := $(PROJ).json

skeleton/MODULE.cpp

@@ -9,12 +9,17 @@ class {MODULE} : public ScreensaverPlugin {
         int fps() const override;
         void update() override;
         void render() override;
+        std::string version() const override;
 };
 
 ScreensaverPlugin* create_instance() {
     return new {MODULE};
 }
 
+std::string {MODULE}::version() const {
+    return "1.0.0";
+}
+
 int {MODULE}::fps() const {
     return 30;
 }

src/main.cpp

@@ -42,7 +42,6 @@ void print_help() {
 
 void list_plugins() {
     for (const auto& elem : sc::plugin<ScreensaverPlugin>::all()) {
-
         std::cout << elem.first << " (" << elem.second()->version() << ")\n";
     }
 }
@@ -73,6 +72,7 @@ bool handle_window_resize(const SDL_Event& event, bool quit) {
         cairo_rectangle_t r {0, 0, static_cast<double>(event.window.data1), static_cast<double>(event.window.data2)};
         if (main_saver) {
             main_saver->setup(main_context.get(), r);
+            main_saver->size_changed();
         }
     }
     return quit;