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Example2

This example shows how an application programmer can control the behaviour of the table by inheriting the QdbtTabular class. In the example three modified tables are created. The following is changed:

rows/cells cannot be selected by the user only from the program.
the header is removed for all three tables.
the ability to edit cells is disabled.
clicking the right mouse button on a cell pops up a menu, the item selected from the menu changes the cell that was clicked.
the cell the mouse is on is tracked and its text is displayed in the lower left corner.
tooltips are disabled
The initial size of the tables is set as small as possible without truncating the cell's text.
The column of each table is resized as the main widget resizes.

The header file:

#ifndef _EXAMPLE2_H
#define _EXAMPLE2_H

#include <qwidget.h>
#include <qlabel.h>
#include <qpopmenu.h>

#include <qdbt/qdbttabular.h>

class MyTabular : public QdbtTabular
{
  Q_OBJECT

  public:
    MyTabular(QWidget *parent=0,const char *name=0,WFlags f=0);
   ~MyTabular();
    void buildPopupMenu();
  
  signals:
    void setStatus(const char *);

  public slots:
    void setCellText(int index);

  protected:
    void mouseMoveEvent(QMouseEvent *);
    void mousePressEvent(QMouseEvent *);
    void leaveTableEvent(QEvent *e);
    void resizeEvent(QResizeEvent *);

  private:
    QPopupMenu *popMenu;
    int clickedRow,clickedCol;
};

class Example : public QWidget
{
  Q_OBJECT

  public:
    Example(QWidget *parent=0, const char *name=0, WFlags f=0);
   ~Example();

  public slots:
    void showStatus(const char *);

  private:
    QLabel *status;
};

#endif

The source file:

#include <stdio.h>
#include <stdlib.h>

#include <qapp.h>
#include <qlayout.h>
#include <qpushbt.h>
#include <qlabel.h>
// a little hack to be able to read the text of an item of a QPopupMenu 
#define INCLUDE_MENUITEM_DEF 1
#include <qmenudta.h>

#include <qdbt/qdbttabcell.h>
#include "example2.h"


MyTabular::MyTabular(QWidget *parent,const char *name,WFlags f) :
     QdbtTabular(parent,name,f)
{
  popMenu = 0;
}

MyTabular::~MyTabular()
{
}

void MyTabular::mousePressEvent(QMouseEvent *e)
{
  if (e->button()==RightButton) // Right mouse button was clicked
  {
    // Compute the cell that was selected
    clickedRow=findRow(e->y());
    clickedCol=findCol(e->x());
    // If the cell is valid we show a popup menu at the location of the 
    // mouse press. 
    if (popMenu && clickedRow!=-1 && clickedCol!=-1) 
    {
      popMenu->popup(mapToGlobal(e->pos()),clickedRow);
      setRowSelected(clickedRow,TRUE);
    }
  }
}

void MyTabular::mouseMoveEvent(QMouseEvent *e)
{
  // compute the row and col of the cell the mouse is on
  int row=findRow(e->y()); 
  int col=findCol(e->x());
  if (row!=-1 && col!=-1) // location is valid
    emit setStatus(cell(row,col)->text());  // display the cell's text
  else
    emit setStatus("none"); 
}

void MyTabular::leaveTableEvent(QEvent *)
{
  // Set the status to `none' if the mouse leaves the table 
  setStatus("none");
}

void MyTabular::resizeEvent(QResizeEvent *)
{
  // Set the column to its maximum width
  // QdbtTabular has a frame, so we must
  // substract its width twice (left and right)
  setColumnWidth(0,width()-2*frameWidth());
}

void MyTabular::setCellText(int index)
{
  // Get the selected text
  const char *text=popMenu->findItem(index)->text();
  // Copy the cell 
  // (no check needed because we know cell() does not return null)
  QdbtTableCell c(*cell(clickedRow,clickedCol));
  // Set the selected text
  c.setText(text);
  // If the chosen text differs from the one original in the table we
  // select the row
  setRowSelected(clickedRow,index!=clickedRow);
  // Change the table so it contains the new cell
  changeCell(&c,clickedRow,clickedCol);
}

void MyTabular::buildPopupMenu()
{
  // create a popupMenu object
  popMenu=new QPopupMenu();
  // call setCellText() whenever the user activates an item
  connect(popMenu,SIGNAL(activated(int)),SLOT(setCellText(int)));
  // add an item for each cell in the table 
  int i; for (i=0;i<numRows();i++) popMenu->insertItem(cell(i,0)->text());
}

// constructor
Example::Example(QWidget *parent,const char *name, WFlags f) 
      : QWidget(parent,name,f)
{
  // Set the caption of the window
  setCaption("Example2");

  // The Layout managers
  QGridLayout *layout  = new QGridLayout(this,2,1,5);
  QGridLayout *tables  = new QGridLayout(1,3,5);
  QBoxLayout  *buttons = new QBoxLayout(QBoxLayout::LeftToRight);
  
  // create three tables
  MyTabular *tabular1=new MyTabular(this);
  MyTabular *tabular2=new MyTabular(this);
  MyTabular *tabular3=new MyTabular(this);

  // set the table size (1 column 10 rows each)
  tabular1->setDimensions(10,1);
  tabular2->setDimensions(10,1);
  tabular3->setDimensions(10,1);

  // hide the headers of the tables
  tabular1->hideHeader();
  tabular2->hideHeader();
  tabular3->hideHeader();

  int i;
  for (i=0;i<10;i++)
  {
    QString nameLeft,nameRight,nameCenter;
    nameLeft.sprintf("left%d\n",i);
    nameCenter.sprintf("center%d\n",i);
    nameRight.sprintf("right%d\n",i);
    QdbtTableCell cell;

    cell.setAlignment(AlignLeft);
    cell.setText(nameLeft);
    tabular1->changeCell(&cell,i,0);
    tabular1->setRowSelectable(i,FALSE);  

    cell.setAlignment(AlignCenter);
    cell.setText(nameCenter);
    tabular2->changeCell(&cell,i,0);
    tabular2->setRowSelectable(i,FALSE);  

    cell.setAlignment(AlignRight);
    cell.setText(nameRight);
    tabular3->changeCell(&cell,i,0);
    tabular3->setRowSelectable(i,FALSE);  
  }

  // Create a popup menu for each table
  tabular1->buildPopupMenu();
  tabular2->buildPopupMenu();
  tabular3->buildPopupMenu();

  // Make sure all cells fit
  tabular1->fitAll();
  tabular2->fitAll();
  tabular3->fitAll();

  // Set the minimum sizes of the tables
  tabular1->setMinimumSize(tabular1->sizeHint());
  tabular2->setMinimumSize(tabular2->sizeHint());
  tabular3->setMinimumSize(tabular3->sizeHint());

  // Since all cells are visible, we do not need tooltips
  tabular1->disableTooltips();
  tabular2->disableTooltips();
  tabular3->disableTooltips();
  
  // Create the control button
  QPushButton *close  = new QPushButton("Close",this);
  status = new QLabel("none    ",this);

  // Set their minimum sizes
  close ->setMinimumSize(close->sizeHint());
  status->setMinimumSize(status->sizeHint());

  // Add Widgets and layouts to the layout-manager
  layout->addLayout(tables,0,0);
  layout->addLayout(buttons,1,0);
  layout->setColStretch(0,1); // make the table strechable
  layout->setRowStretch(0,1);

  // Add Widgets to the tables layout
  tables->addWidget(tabular1,0,0);
  tables->addWidget(tabular2,0,1);
  tables->addWidget(tabular3,0,2);

  // Add Widgets to the button layout
  buttons->addWidget(status);
  buttons->addStretch(1);
  buttons->addWidget(close);

  // don't forget to activate the top layout manager
  layout->activate();

  // Let the close button quit the application
  connect(close,  SIGNAL(clicked()),qApp,SLOT(quit()));
  
  // Send the cell that is mouse is currently over to the label
  // for each of the tables.
  connect(tabular1, SIGNAL( setStatus(const char *) ),
                    SLOT(  showStatus(const char *) ) );

  connect(tabular2, SIGNAL( setStatus(const char *) ),
                    SLOT(  showStatus(const char *) ) );

  connect(tabular3, SIGNAL( setStatus(const char *) ),
                    SLOT(  showStatus(const char *) ) );

  // Resize the widget to its minimal size
  resize(layout->mainWidget()->sizeHint());
}

// destructor
Example::~Example()
{
}

void Example::showStatus(const char *text)
{
  if (strcmp(status->text(),text)) status->setText(text);
}

int main(int argc,char **argv)
{
  QApplication app(argc, argv);
  Example example;
  app.setMainWidget(&example);
  example.show();
  return app.exec();  
}

Generated at 21:52, 1998/03/04 for QdbtTabular by