QGIS » QGIS Application

#include <QApplication>

#include <QVBoxLayout>

#include <QMainWindow>

#include <QTreeWidget>

#include <QWidget>

#include <QStringList>

#include <QTreeWidgetItem>

#include <QString>

#include <QMouseEvent>

#include <QLine>

#include <QPalette>

#include <QResizeEvent>

#include <QPoint>

#include <QDebug>

enum LEGEND_ITEM_TYPE

{

  LEGEND_GROUP                = QTreeWidgetItem::UserType + 0,

  LEGEND_LAYER                = QTreeWidgetItem::UserType + 1,

  LEGEND_PROPERTY_GROUP       = QTreeWidgetItem::UserType + 2,

  LEGEND_PROPERTY_ITEM        = QTreeWidgetItem::UserType + 3,

  LEGEND_SYMBOL_GROUP         = QTreeWidgetItem::UserType + 4,

  LEGEND_SYMBOL_ITEM          = QTreeWidgetItem::UserType + 5,

  LEGEND_VECTOR_SYMBOL_ITEM   = QTreeWidgetItem::UserType + 6,

  LEGEND_LAYER_FILE_GROUP     = QTreeWidgetItem::UserType + 7,

  LEGEND_LAYER_FILE           = QTreeWidgetItem::UserType + 8

} ;

class TreeWidget : public QTreeWidget

{

    Q_OBJECT

    public:

    TreeWidget(QWidget *parent = 0)

      : QTreeWidget(parent), dragging(false), dragged(NULL), dropOn(NULL)

    {

      line = new QWidget(viewport());

      hideLine();

      line->setAutoFillBackground(true);

      QPalette pal = line->palette();

      pal.setColor(line->backgroundRole(), Qt::blue);

      line->setPalette(pal);

      setColumnCount(2);

      setHeaderLabels(QStringList() << "Name" << "Info");

      setRootIsDecorated(true);

      int i = 0;

      for (; i<5; ++i) {

        new QTreeWidgetItem(invisibleRootItem(), QStringList(QString("Item %1").arg(i)) << QString("Layer"));

      }

      QTreeWidgetItem *group1 = new QTreeWidgetItem(invisibleRootItem(), QStringList(QString("Item %1").arg(i++)) << QString("Group"), LEGEND_GROUP);

      for (; i<9; ++i) {

        new QTreeWidgetItem(group1, QStringList(QString("Item %1").arg(i)) << QString("Layer"));

      }

      QTreeWidgetItem *group2 = new QTreeWidgetItem(invisibleRootItem(), QStringList(QString("Item %1").arg(i++)) << QString("Group"), LEGEND_GROUP);

      for (; i<13; ++i) {

        new QTreeWidgetItem(group2, QStringList(QString("Item %1").arg(i)) << QString("Layer"));

      }

      setDragDropMode(NoDragDrop);

    }

    void mousePressEvent(QMouseEvent *e)

    {

      if (e->button() == Qt::LeftButton) {

        lastPress = e->pos();

        QTreeWidgetItem *item = itemAt(e->pos());

        dragged = item;

      }

      QTreeWidget::mousePressEvent(e);

    }

    void mouseMoveEvent(QMouseEvent *e)

    {

      if (dragging) {

        QTreeWidgetItem *item = itemAt(e->pos());

        if (item) {

          dropOn = item;

          int item_top = visualItemRect(item).top();

          int item_bottom = visualItemRect(item).bottom();

          int item_middle = ( item_top + item_bottom + 1 ) / 2;

          int item_left =  visualItemRect(item).left();

          if (dropOn != dragged ) {

            if (e->pos().y() < item_middle )

            {

              showLine(item_top+1, item_left);

              dropBottom = false;

            }

            else

            {

              showLine(item_bottom-2, item_left);

              dropBottom = true;

            }

            // dropBottom doesn't care if dropping onto itself.

          }

          else

          {

            hideLine();

          }

        } else if (e->pos().y() >= 0) {

          dropOn = NULL; // Means after items

          showLine(visualItemRect( lastVisibleItem() ).bottom() + 1, 0);

        } else {

          dropOn = NULL;

          hideLine();

        }

        e->accept();

      } else if (e->buttons() == Qt::LeftButton

      && (e->pos() - lastPress).manhattanLength() >= QApplication::startDragDistance()) {

        line->show();

        dragging = true;

      } else {

        QTreeWidget::mouseMoveEvent(e);

      }

    }

    void hideLine()

    {

      line->setGeometry(0, -100, 1, 1);

    }

    void showLine(int y, int left)

    {

      line->setGeometry(left, y, viewport()->width(), 2);

    }

    void mouseReleaseEvent(QMouseEvent *e)

    {

      if (dragging) {

        hideLine();

        if (dragged && !(dragged == dropOn) && !isDescendantOf( dragged, dropOn ) )

        {

          QTreeWidgetItem *draggedParent = dragged->parent() ?  dragged->parent() : invisibleRootItem();

          clearSelection();

          draggedParent->removeChild(dragged);

          if ( dropOn )

          {

            // We're dropping on something

            QTreeWidgetItem *dropOnParent = dropOn->parent() ?  dropOn->parent() : invisibleRootItem();

            if ( dropBottom )

            {

              // Releasing event in bottom half of object. If group, insert into, else after.

              if (dropOn->type() == LEGEND_GROUP )

              {

                // Drop into

                dropOn->insertChild(0, dragged);

              }

              else

              {

                // Drop after

                dropOnParent->insertChild(dropOnParent->indexOfChild( dropOn ) + 1, dragged);

              }

            }

            else

            {

              // Releasing event in top half of object. Insert before, always

              dropOnParent->insertChild(dropOnParent->indexOfChild( dropOn ), dragged);

            }

          }

          else

          {

            // We're not dropping on something, add last of the top level items.

            invisibleRootItem()->insertChild(invisibleRootItem()->childCount(), dragged);

          }

          setCurrentItem(dragged);

        }

        dropOn = dragged = NULL;

        dragging = false;

        e->accept();

      } else {

        QTreeWidget::mouseReleaseEvent(e);

      }

    }

    QTreeWidgetItem *lastVisibleItem()

    {

      QTreeWidgetItem *current;

      QTreeWidgetItem *next;

      current = topLevelItem( topLevelItemCount() - 1 );

      while ( ( next = itemBelow( current ) ) )

      {

        current = next;

      }

      return current;

    }

    bool isDescendantOf(QTreeWidgetItem *parent, QTreeWidgetItem *child)

    {

      // Search depth first

      if ( parent && child )

      {

        if ( parent == child->parent() )

        {

          return true;

        }

        for( int i = 0; i < parent->childCount(); i++ )

        {

          if ( isDescendantOf( parent->child(i), child ) )

          {

            return true;

          }

        }

      }

      return false;

    }

  private:

    QWidget *line;

    QPoint lastPress;

    bool dragging;

    bool dropBottom;

    QTreeWidgetItem *dragged, *dropOn;

};

#include "main.moc"

int main(int argc, char **argv)

{

  QApplication a(argc, argv);

  TreeWidget w;

  w.show();

  return a.exec();

}