Investigation: install a custom stylesheet

research/SConscript

@@ -21,6 +21,7 @@ experiments = [ envR.Program('try', ['try.cpp'] + core)          #### to try out
               
               , envRGtk.Program('gtk-canvas-experiment', ['gtk-canvas-experiment.cpp', 'gtk-canvas-main.cpp'] + core)
               , envRGtk.Program('gtk-style-experiment',  ['gtk-style-experiment.cpp'] + core)
+              , env.GuiResource('gtk-style-experiment.css')
               ]
 
 #

research/gtk-style-experiment.cpp

@@ -30,19 +30,43 @@
 
 
 #include "stage/gtk-base.hpp"
+#include "lib/searchpath.hpp"
 #include "lib/error.hpp"
+#include "lib/util.hpp"
 
+#include <string>
+
+using util::cStr;
+using std::string;
 
 namespace research {
   
+  namespace {
+    const string STYLESHEET_NAME{"gtk-style-experiment.css"};
+    const string RESOURCE_PATH{"$ORIGIN/gui"};
+    
+    const string CLASS_experiment{"experiment"};
+  }
+  
+  using CairoC = stage::PCairoContext const&;
+  using StyleC = stage::PStyleContext const&;
+  
+  using stage::PStyleContext;
+  
   
   class Canvas
     : public Gtk::Layout
     {
-      bool shallDraw_;
+      bool shallDraw_       = false;
       bool recalcExtension_ = false;
       
+      StyleC style_;
+      
     public:
+      Canvas(StyleC refStyle)
+        : style_{refStyle}
+      { }
+      
       void adjustSize();
       void enableDraw (bool);
       
@@ -67,8 +91,12 @@ namespace research {
       Gtk::CheckButton toggleDraw_;
       Gtk::Frame frame_;
       Gtk::ScrolledWindow scroller_;
+      
+      PStyleContext pStyle_;
       Canvas canvas_;
       
+      PStyleContext setupStyle();
+      
       void experiment_1();
       void experiment_2();
     };
@@ -78,11 +106,12 @@ namespace research {
   
   StyleTestPanel::StyleTestPanel()
     : Box{}
-    , twoParts_(Gtk::ORIENTATION_VERTICAL)
-    , buttons_()
-    , frame_("Gtk::StyleContext Experiments")
-    , scroller_()
-    , canvas_()
+    , twoParts_{Gtk::ORIENTATION_VERTICAL}
+    , buttons_{}
+    , frame_{"Gtk::StyleContext Experiments"}
+    , scroller_{}
+    , pStyle_{}
+    , canvas_{pStyle_}
     {
       twoParts_.pack_start(buttons_, Gtk::PACK_SHRINK);
       twoParts_.pack_start(frame_);
@@ -120,6 +149,9 @@ namespace research {
       scroller_.set_border_width(10);
       scroller_.add(canvas_);
       
+      frame_.get_style_context()->add_class(CLASS_experiment);
+      pStyle_ = setupStyle();
+      
       canvas_.adjustSize();
       
       // show everything....
@@ -128,6 +160,29 @@ namespace research {
     }
   
   
+  
+  PStyleContext
+  StyleTestPanel::setupStyle()
+  {
+    auto screen = Gdk::Screen::get_default();
+    auto css_provider = Gtk::CssProvider::create();
+    try
+      {
+        css_provider->load_from_path (lib::resolveModulePath (STYLESHEET_NAME, RESOURCE_PATH));
+      }
+    catch(Glib::Error const& failure)
+      {
+        WARN (stage, "Failure while loading stylesheet '%s': %s", cStr(STYLESHEET_NAME), cStr(failure.what()));
+      }
+    
+    Gtk::StyleContext::add_provider_for_screen (screen, css_provider,
+                                                GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+    
+    return PStyleContext{};
+  }
+  
+  
+  
   void
   StyleTestPanel::experiment_1()
   {
@@ -183,7 +238,7 @@ namespace research {
   
   
   bool
-  Canvas::on_draw(Cairo::RefPtr<Cairo::Context> const& cox)
+  Canvas::on_draw(CairoC cox)
   {
     if (shallDraw_)
       {

research/gtk-style-experiment.css

@@ -0,0 +1,51 @@
+/*
+  gtk-style-experiment.css  -  investigate GTKs CSS implementation
+
+  Copyright (C)         Lumiera.org
+    2019,               Hermann Vosseler <Ichthyostega@web.de>
+
+  Styles and Graphics of the Lumiera GUI can be used and redistributed
+  under the the terms of the GNU General Public License version 2 or
+  above, or (at your option) under Creative Commons CC-By-SA.
+
+* ********************************************************/
+
+
+/* CSS stylesheet loaded by gtk-style-experiment.cpp on top of
+ * the system theme, with GTK_STYLE_PROVIDER_PRIORITY_APPLICATION
+ */
+
+
+
+
+/* ---------- Styles for Lumiera Widgets ---------- */
+
+
+/* ---------- Styles for special markup ---------- */
+
+
+/* special styling for the frame widget within the main window....
+ * This styling will be picked up by our custom drawing code
+ */
+  frame.experiment {
+    margin: 2ex 0;
+    border: 5px inset IndianRed;
+    background-color: Lime;
+}
+  fork.timeline frame.timeline.ruler {
+    margin: 3ex 0;
+    border: 3px outset GoldenRod;
+    background-color: DarkCyan;
+}
+  .track-slope-deep2 {
+    border-width: 10px;
+}
+  .track-slope-deep3 {
+    border-width: 14px;
+}
+  .track-slope-deep4 {
+    border-width: 17px;
+}
+  .track-slope-verydeep {
+    border-width: 20px;
+}