Fixed the issue of dark tree expansion icons

Prior to this bug fix, the expansion icons were
not visible with a dark background on some platforms
(i.e. Gtk style, native Windows style).

src/laybasic/layHierarchyControlPanel.cc

@@ -35,6 +35,9 @@
 #include <QLabel>
 #include <QToolButton>
 #include <QCheckBox>
+#include <QProxyStyle>
+#include <QPainter>
+#include <QPen>
 
 #include "dbClipboard.h"
 #include "dbClipboardData.h"
@@ -321,6 +324,8 @@ HierarchyControlPanel::HierarchyControlPanel (lay::LayoutView *view, QWidget *pa
   mp_view->cellviews_changed_event.add (this, &HierarchyControlPanel::update_required);
   mp_view->hier_changed_event.add (this, &HierarchyControlPanel::update_required);
 
+  mp_tree_style.reset (new BackgroundAwareTreeStyle (style ()));
+
   do_update_content ();
 }
 
@@ -660,13 +665,6 @@ void
 HierarchyControlPanel::set_background_color (QColor c)
 {
   m_background_color = c;
-  QColor hl;
-  if (c.green () > 128) {
-    hl = QColor (192, 192, 255);
-  } else {
-    hl = QColor (0, 0, 80);
-  }
-
   for (std::vector <QTreeView *>::const_iterator f = mp_cell_lists.begin (); f != mp_cell_lists.end (); ++f) {
     QPalette pl ((*f)->palette ());
     pl.setColor (QPalette::Base, c);
@@ -889,6 +887,7 @@ HierarchyControlPanel::do_update_content (int cv_index)
 
     HCPCellTreeWidget *cell_list = new HCPCellTreeWidget (cl_frame, "tree");
     cl_ly->addWidget (cell_list);
+    cell_list->setStyle (mp_tree_style.get ());
     cell_list->setModel (new CellTreeModel (cell_list, mp_view, cv_index, m_flat ? CellTreeModel::Flat : 0, 0, m_sorting));
     cell_list->setUniformRowHeights (true);
 

src/laybasic/layHierarchyControlPanel.h

@@ -300,6 +300,7 @@ private:
   QColor m_text_color;
   tl::DeferredMethod<HierarchyControlPanel> m_do_update_content_dm;
   tl::DeferredMethod<HierarchyControlPanel> m_do_full_update_content_dm;
+  std::auto_ptr<QStyle> mp_tree_style;
 
   //  locate the CellTreeItem in the tree corresponding to a partial path starting from p.
   CellTreeItem *find_child_item (cell_path_type::const_iterator start, cell_path_type::const_iterator end, CellTreeItem *p);

src/laybasic/layLayerControlPanel.cc

@@ -308,6 +308,8 @@ LayerControlPanel::LayerControlPanel (lay::LayoutView *view, db::Manager *manage
 
   mp_model = new lay::LayerTreeModel (this, view);
   mp_layer_list = new LCPTreeWidget (this, mp_model, "layer_tree");
+  mp_ll_style.reset (new BackgroundAwareTreeStyle (mp_layer_list->style ()));
+  mp_layer_list->setStyle (mp_ll_style.get ());
   mp_model->set_font (mp_layer_list->font ());
   /*
    * At least with Qt 4.2.x setting uniform row heights has a strange side effect: 

src/laybasic/layLayerControlPanel.h

@@ -326,6 +326,7 @@ public slots:
 private:
   QTabBar *mp_tab_bar;
   LCPTreeWidget *mp_layer_list;
+  std::auto_ptr<QStyle> mp_ll_style;
   LayerTreeModel *mp_model;
   lay::LayoutView *mp_view;
   bool m_needs_update;

src/laybasic/layWidgets.cc

@@ -934,8 +934,9 @@ const int le_decoration_space = 2; //  additional distance between decoration ic
 
 DecoratedLineEdit::DecoratedLineEdit (QWidget *parent)
   : QLineEdit (parent),
-    m_clear_button_enabled (false), m_options_button_enabled (false), mp_options_menu (0),
-    m_escape_signal_enabled (false), m_tab_signal_enabled (false)
+    m_clear_button_enabled (false), m_options_button_enabled (false),
+    m_escape_signal_enabled (false), m_tab_signal_enabled (false),
+    mp_options_menu (0)
 {
   mp_options_label = new QLabel (this);
   mp_options_label->hide ();
@@ -1105,5 +1106,84 @@ void DecoratedLineEdit::resizeEvent (QResizeEvent * /*event*/)
   }
 }
 
+// -------------------------------------------------------------
+//  BackgroundAwareTreeStyle implementation
+
+BackgroundAwareTreeStyle::BackgroundAwareTreeStyle (QStyle *org_style)
+  : QProxyStyle (org_style)
+{
+  //  .. nothing yet ..
+}
+
+void
+BackgroundAwareTreeStyle::drawPrimitive (QStyle::PrimitiveElement pe, const QStyleOption *opt, QPainter *p, const QWidget *w) const
+{
+  if (pe == PE_IndicatorBranch) {
+
+    static const int sz = 9;
+
+    int mid_h = opt->rect.x () + opt->rect.width () / 2;
+    int mid_v = opt->rect.y () + opt->rect.height () / 2;
+
+    if (opt->state & State_Children) {
+
+      QColor c;
+
+      QPalette::ColorGroup cg = QPalette::Disabled;
+      if ((w && w->isEnabled ()) || (!w && (opt->state & State_Enabled))) {
+        if ((w && w->hasFocus ()) || (!w && (opt->state & State_HasFocus))) {
+          cg = QPalette::Normal;
+        } else {
+          cg = QPalette::Inactive;
+        }
+      }
+      if (opt->state & State_Selected) {
+        c = opt->palette.color (cg, QPalette::HighlightedText);
+      } else {
+        c = opt->palette.color (cg, QPalette::Text);
+      }
+      if (! (opt->state & State_MouseOver)) {
+        if (c.green () < 128) {
+          c = QColor ((c.red () * 3 + 255) / 4, (c.green () * 3 + 255) / 4, (c.blue () * 3 + 255) / 4);
+        } else {
+          c = QColor ((c.red () * 8) / 9, (c.green () * 8) / 9, (c.blue () * 8) / 9);
+        }
+      }
+
+      QPen old_pen = p->pen ();
+      p->setPen (Qt::NoPen);
+      QBrush old_brush = p->brush ();
+      p->setBrush (c);
+      QPainter::RenderHints old_rh = p->renderHints ();
+      p->setRenderHints (QPainter::Antialiasing);
+
+      if (opt->state & State_Open) {
+        QPoint points[] = {
+          QPoint (mid_h - sz / 2, mid_v - sz / 3),
+          QPoint (mid_h + sz / 2, mid_v - sz / 3),
+          QPoint (mid_h, mid_v + sz / 3)
+        };
+        p->drawPolygon (points, sizeof (points) / sizeof (points[0]));
+      } else {
+        QPoint points[] = {
+          QPoint (mid_h - sz / 3, mid_v - sz / 2),
+          QPoint (mid_h + sz / 3, mid_v),
+          QPoint (mid_h - sz / 3, mid_v + sz / 2)
+        };
+        p->drawPolygon (points, sizeof (points) / sizeof (points[0]));
+      }
+
+      p->setPen (old_pen);
+      p->setBrush (old_brush);
+      p->setRenderHints (old_rh);
+      return;
+
+    }
+
+  }
+
+  QProxyStyle::drawPrimitive (pe, opt, p, w);
+}
+
 }
 

src/laybasic/layWidgets.h

@@ -30,6 +30,7 @@
 #include <QComboBox>
 #include <QLabel>
 #include <QLineEdit>
+#include <QProxyStyle>
 
 namespace db
 {
@@ -443,6 +444,21 @@ private:
   int m_default_left_margin, m_default_right_margin;
 };
 
+/**
+ *  @brief A style tailoring the drawing of the branch indicator
+ *  This proxy style is making the branch indicator a triangle and aware of the
+ *  palette of the tree.
+ *  The default Gtk style is not, hence making the background dark means the
+ *  triangles become invisible.
+ */
+class BackgroundAwareTreeStyle
+  : public QProxyStyle
+{
+public:
+  BackgroundAwareTreeStyle (QStyle *org_style);
+  void drawPrimitive (PrimitiveElement pe, const QStyleOption *opt, QPainter *p, const QWidget *w) const;
+};
+
 } // namespace lay
 
 #endif