From 8516a4f5383dd8e5713ee7ed21bdc6dc1b215717 Mon Sep 17 00:00:00 2001
From: Bill Somerville <bill@classdesign.com>
Date: Tue, 3 Nov 2020 20:28:29 +0000
Subject: [PATCH] New combo box with a list of checkable items

---
 CMakeLists.txt                    |  1 +
 widgets/CheckableItemComboBox.cpp | 93 +++++++++++++++++++++++++++++++
 widgets/CheckableItemComboBox.hpp | 36 ++++++++++++
 widgets/widgets.pri               |  7 ++-
 4 files changed, 135 insertions(+), 2 deletions(-)
 create mode 100644 widgets/CheckableItemComboBox.cpp
 create mode 100644 widgets/CheckableItemComboBox.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3dc5b0823..77cfa3377 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -241,6 +241,7 @@ set (wsjt_qt_CXXSRCS
   logbook/Multiplier.cpp
   Network/NetworkAccessManager.cpp
   widgets/LazyFillComboBox.cpp
+  widgets/CheckableItemComboBox.cpp
   )
 
 set (wsjt_qtmm_CXXSRCS
diff --git a/widgets/CheckableItemComboBox.cpp b/widgets/CheckableItemComboBox.cpp
new file mode 100644
index 000000000..3ef926243
--- /dev/null
+++ b/widgets/CheckableItemComboBox.cpp
@@ -0,0 +1,93 @@
+#include "CheckableItemComboBox.hpp"
+
+#include <QStyledItemDelegate>
+#include <QStandardItemModel>
+#include <QStandardItem>
+#include <QLineEdit>
+#include <QEvent>
+#include <QListView>
+
+class CheckableItemComboBoxStyledItemDelegate
+  : public QStyledItemDelegate
+{
+public:
+  explicit CheckableItemComboBoxStyledItemDelegate (QObject * parent = nullptr)
+    : QStyledItemDelegate {parent}
+  {
+  }
+
+  void paint (QPainter * painter, QStyleOptionViewItem const& option, QModelIndex const& index) const override
+  {
+    QStyleOptionViewItem& mutable_option = const_cast<QStyleOptionViewItem&> (option);
+    mutable_option.showDecorationSelected = false;
+    QStyledItemDelegate::paint (painter, mutable_option, index);
+  }
+};
+
+CheckableItemComboBox::CheckableItemComboBox (QWidget * parent)
+  : QComboBox {parent}
+  , model_ {new QStandardItemModel()}
+{
+  setModel (model_.data ());
+
+  setEditable (true);
+  lineEdit ()->setReadOnly (true);
+  lineEdit ()->installEventFilter (this);
+  setItemDelegate (new CheckableItemComboBoxStyledItemDelegate {this});
+
+  connect (lineEdit(), &QLineEdit::selectionChanged, lineEdit(), &QLineEdit::deselect);
+  connect (static_cast<QListView *> (view ()), &QListView::pressed, this, &CheckableItemComboBox::item_pressed);
+  connect (model_.data (), &QStandardItemModel::dataChanged, this, &CheckableItemComboBox::model_data_changed);
+}
+
+QStandardItem * CheckableItemComboBox::addCheckItem (QString const& label, QVariant const& data
+                                                     , Qt::CheckState checkState)
+{
+  auto * item = new QStandardItem {label};
+  item->setCheckState (checkState);
+  item->setData (data);
+  item->setFlags (Qt::ItemIsUserCheckable | Qt::ItemIsEnabled);
+  model_->appendRow (item);
+  update_text ();
+  return item;
+}
+
+bool CheckableItemComboBox::eventFilter (QObject * object, QEvent * event)
+{
+  if (object == lineEdit() && event->type () == QEvent::MouseButtonPress)
+    {
+      showPopup();
+      return true;
+    }
+  return false;
+}
+
+void CheckableItemComboBox::update_text()
+{
+  QString text;
+  for (int i = 0; i < model_->rowCount (); ++i)
+    {
+      if (model_->item (i)->checkState () == Qt::Checked)
+        {
+          if (text.size ())
+            {
+              text+= ", ";
+            }
+          text += model_->item (i)->data ().toString ();
+        }
+    }
+  lineEdit ()->setText (text);
+}
+
+void CheckableItemComboBox::model_data_changed ()
+{
+  update_text ();
+}
+
+void CheckableItemComboBox::item_pressed (QModelIndex const& index)
+{
+  QStandardItem * item = model_->itemFromIndex (index);
+  item->setCheckState (item->checkState () == Qt::Checked ? Qt::Unchecked : Qt::Checked);
+}
+
+#include "widgets/moc_CheckableItemComboBox.cpp"
diff --git a/widgets/CheckableItemComboBox.hpp b/widgets/CheckableItemComboBox.hpp
new file mode 100644
index 000000000..2aa3e9831
--- /dev/null
+++ b/widgets/CheckableItemComboBox.hpp
@@ -0,0 +1,36 @@
+#ifndef CHECKABLE_ITEM_COMBO_BOX_HPP__
+#define CHECKABLE_ITEM_COMBO_BOX_HPP__
+
+#include <QComboBox>
+#include <QScopedPointer>
+
+class QStandardItemModel;
+class QStandardItem;
+
+/**
+ * @brief QComboBox with support of checkboxes
+ * http://stackoverflow.com/questions/8422760/combobox-of-checkboxes
+ */
+class CheckableItemComboBox
+  : public QComboBox
+{
+  Q_OBJECT
+
+public:
+  explicit CheckableItemComboBox (QWidget * parent = nullptr);
+  QStandardItem * addCheckItem (QString const& label, QVariant const& data, Qt::CheckState checkState);
+
+protected:
+  bool eventFilter (QObject *, QEvent *) override;
+
+private:
+  void update_text();
+
+  Q_SLOT void model_data_changed ();
+  Q_SLOT void item_pressed (QModelIndex const&);
+
+private:
+  QScopedPointer<QStandardItemModel> model_;
+};
+
+#endif
diff --git a/widgets/widgets.pri b/widgets/widgets.pri
index 7a364c4ee..6a623d825 100644
--- a/widgets/widgets.pri
+++ b/widgets/widgets.pri
@@ -10,7 +10,9 @@ SOURCES += \
   widgets/AbstractLogWindow.cpp \
   widgets/FrequencyLineEdit.cpp widgets/FrequencyDeltaLineEdit.cpp \
   widgets/FoxLogWindow.cpp widgets/CabrilloLogWindow.cpp \
-  widgets/HelpTextWindow.cpp widgets/RestrictedSpinBox.cpp
+  widgets/HelpTextWindow.cpp widgets/RestrictedSpinBox.cpp \
+  widgets/LazyFillComboBox.cpp widgets/CheckableItemComboBox.cpp
+
 HEADERS  += \
   widgets/mainwindow.h widgets/plotter.h \
   widgets/about.h widgets/widegraph.h  \
@@ -22,7 +24,8 @@ HEADERS  += \
   widgets/ExportCabrillo.h widgets/AbstractLogWindow.hpp \
   widgets/FoxLogWindow.hpp widgets/CabrilloLogWindow.hpp \
   widgets/DateTimeEdit.hpp widgets/HelpTextWindow.hpp \
-  widgets/RestrictedSpinBox.hpp
+  widgets/RestrictedSpinBox.hpp \
+  widgets/LazyFillComboBox.hpp widgets/CheckableItemComboBox.hpp
 
 FORMS    += \
   widgets/mainwindow.ui widgets/about.ui \