qitemdelegate.cpp

qt-x11-opensource-src-4.1.4.tar.gz源码

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#include "qitemdelegate.h"

#ifndef QT_NO_ITEMVIEWS
#include <qabstractitemmodel.h>
#include <qapplication.h>
#include <qlineedit.h>
#include <qpainter.h>
#include <qpalette.h>
#include <qpoint.h>
#include <qrect.h>
#include <qsize.h>
#include <qstyle.h>
#include <qstyleoption.h>
#include <qevent.h>
#include <qpixmap.h>
#include <qbitmap.h>
#include <qpixmapcache.h>
#include <qitemeditorfactory.h>
#include <private/qobject_p.h>
#include <private/qdnd_p.h>
#include <qdebug.h>

void qt_format_text(const QFont&, const QRectF&,
                    int, const QString&, QRectF *,
                    int, int*, int, QPainter*);

static const int textMargin = 3;

class QItemDelegatePrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QItemDelegate)

public:
    QItemDelegatePrivate() : f(0) {}

    inline const QItemEditorFactory *editorFactory() const
        { return f ? f : QItemEditorFactory::defaultFactory(); }

    QItemEditorFactory *f;
};

/*!
    \class QItemDelegate

    \brief The QItemDelegate class provides display and editing facilities for
    data items from a model.

    \ingroup model-view
    \mainclass

    QItemDelegate can be used to provide custom display features and editor
    widgets for item views based on QAbstractItemView subclasses. Using a
    delegate for this purpose allows the display and editing mechanisms to be
    customized and developed independently from the model and view.

    The QItemDelegate class is one of the \l{Model/View Classes}
    and is part of Qt's \l{Model/View Programming}{model/view framework}.

    When displaying items from a custom model in a standard view, it is
    often sufficient to simply ensure that the model returns appropriate
    data for each of the \l{Qt::ItemDataRole}{roles} that determine the
    appearance of items in views. The default delegate used by Qt's
    standard views uses this role information to display items in most
    of the common forms expected by users. However, it is sometimes
    necessary to have even more control over the appearance of items than
    the default delegate can provide.

    This class provides default implementations of the functions for
    painting item data in a view, and editing data obtained from a model.
    Default implementations of the paint() and sizeHint() virtual functions,
    defined in QAbstractItemDelegate, are provided to ensure that the
    delegate implements the correct basic behavior expected by views. You
    can reimplement these functions in subclasses to customize the
    appearance of items.

    Delegates can be used to manipulate item data in two complementary ways:
    by processing events in the normal manner, or by implementing a
    custom editor widget. The item delegate takes the approach of providing
    a widget for editing purposes that can be supplied to
    QAbstractItemView::setDelegate() or the equivalent function in
    subclasses of QAbstractItemView.

    Only the standard editing functions for widget-based delegates are
    reimplemented here: editor() returns the widget used to change data
    from the model; setEditorData() provides the widget with data to
    manipulate; updateEditorGeometry() ensures that the editor is displayed
    correctly with respect to the item view; setModelData() returns the
    updated data to the model; releaseEditor() indicates that the user has
    completed editing the data, and that the editor widget can be destroyed.

    \section1 Standard Roles and Data Types

    The default delegate used by the standard views supplied with Qt
    associates each standard role (defined by Qt::ItemDataRole) with certain
    data types. Models that return data in these types can influence the
    appearance of the delegate as described in the following table.

    \table
    \header \o Role \o Accepted Types
    \omit
    \row    \o \l Qt::AccessibleDescriptionRole \o QString
    \row    \o \l Qt::AccessibleTextRole \o QString
    \endomit
    \row    \o \l Qt::BackgroundColorRole \o QColor
    \row    \o \l Qt::CheckStateRole \o Qt::CheckState
    \row    \o \l Qt::DecorationRole \o QIcon and QColor
    \row    \o \l Qt::DisplayRole \o QString and types with a string representation
    \row    \o \l Qt::EditRole \o See QItemEditorFactory for details
    \row    \o \l Qt::FontRole \o QFont
    \row    \o \l Qt::SizeHintRole \o QSize
    \omit
    \row    \o \l Qt::StatusTipRole \o 
    \endomit
    \row    \o \l Qt::TextAlignmentRole \o Qt::Alignment
    \row    \o \l Qt::TextColorRole \o QColor
    \omit
    \row    \o \l Qt::ToolTipRole
    \row    \o \l Qt::WhatsThisRole
    \endomit
    \endtable

    If the default delegate does not allow the level of customization that
    you need, it is possible to subclass QItemDelegate to implement the
    desired behavior.

    \section1 Subclassing

    When subclassing QItemDelegate to create a delegate that displays items
    using a custom renderer, it is important to ensure that the delegate can
    render items suitably for all the required states; e.g. selected,
    disabled, checked. The documentation for the paint() function contains
    some hints to show how this can be achieved.

    \sa {Model/View Programming}, QAbstractItemDelegate
*/

/*!
    Constructs an item delegate with the given \a parent.
*/

QItemDelegate::QItemDelegate(QObject *parent)
    : QAbstractItemDelegate(*new QItemDelegatePrivate(), parent)
{

}

/*!
    Destroys the item delegate.
*/

QItemDelegate::~QItemDelegate()
{
}

/*!
    Renders the delegate using the given \a painter and style \a option for
    the item specified by \a index.

    When reimplementing this function in a subclass, you should update the area
    held by the option's \l{QStyleOption::rect}{rect} variable, using the
    option's \l{QStyleOption::state}{state} variable to determine the state of
    the item to be displayed, and adjust the way it is painted accordingly.

    For example, a selected item may need to be displayed differently to
    unselected items, as shown in the following code:

    \quotefromfile itemviews/pixelator/pixeldelegate.cpp
    \skipto QStyle::State_Selected
    \printuntil else
    \dots

    After painting, you should ensure that the painter is returned to its
    the state it was supplied in when this function was called. For example,
    it may be useful to call QPainter::save() before painting and
    QPainter::restore() afterwards.

    \sa QStyle::State
*/

void QItemDelegate::paint(QPainter *painter,
                          const QStyleOptionViewItem &option,
                          const QModelIndex &index) const
{
    Q_ASSERT(index.isValid());

    QStyleOptionViewItem opt = option;

    // set font
    QVariant value = index.data(Qt::FontRole);
    if (value.isValid()) {
        opt.font = qvariant_cast<QFont>(value);
        opt.fontMetrics = QFontMetrics(opt.font);
    }

    // set text alignment
    value = index.data(Qt::TextAlignmentRole);
    if (value.isValid())
        opt.displayAlignment = QFlag(value.toInt());

    // set text color
    value = index.data(Qt::TextColorRole);
    if (value.isValid() && qvariant_cast<QColor>(value).isValid())
        opt.palette.setColor(QPalette::Text, qvariant_cast<QColor>(value));

    // do layout

    // decoration
    value = index.data(Qt::DecorationRole);
    QPixmap pixmap = decoration(opt, value);
    QRect pixmapRect = (pixmap.isNull() ? QRect(0, 0, 0, 0)
                        : QRect(QPoint(0, 0), option.decorationSize));

    // display
    QRect textRect;
    QString text = index.data(Qt::DisplayRole).toString();
    if (!text.isEmpty()) {
        const QString text = index.data(Qt::DisplayRole).toString();
        const QChar *chr = text.constData();
        const QChar *end = chr + text.length();
        while (chr != end
               && *chr != QLatin1Char('\n')
               && *chr != QLatin1Char('\t')
               && *chr != QLatin1Char('&')) ++chr;
        if (chr == end) {
            textRect = QRect(0, 0, opt.fontMetrics.width(text), opt.fontMetrics.lineSpacing());
        } else {
            QRectF result;
            qt_format_text(opt.font, option.rect,
                           Qt::TextDontPrint|Qt::TextDontClip|Qt::TextExpandTabs,
                       text, &result, 0, 0, 0, painter);
            textRect = result.toRect();
        }
    }

    // check
    value = index.data(Qt::CheckStateRole);
    QRect checkRect = check(opt, opt.rect, value);
    Qt::CheckState checkState = static_cast<Qt::CheckState>(value.toInt());

    doLayout(opt, &checkRect, &pixmapRect, &textRect, false);

    // draw the background color
    if (option.showDecorationSelected && (option.state & QStyle::State_Selected)) {
        QPalette::ColorGroup cg = option.state & QStyle::State_Enabled
                                  ? QPalette::Normal : QPalette::Disabled;
        if (cg == QPalette::Normal && !(option.state & QStyle::State_Active))
            cg = QPalette::Inactive;
        painter->fillRect(option.rect, option.palette.brush(cg, QPalette::Highlight));
    } else {
        value = index.data(Qt::BackgroundColorRole);
        if (value.isValid() && qvariant_cast<QColor>(value).isValid())
            painter->fillRect(option.rect, qvariant_cast<QColor>(value));
    }

    // draw the item
    if (checkRect.isValid())
        drawCheck(painter, opt, checkRect, checkState);
    if (pixmapRect.isValid())
        drawDecoration(painter, opt, pixmapRect, pixmap);
    if (!text.isEmpty()) {
        drawDisplay(painter, opt, textRect, text);
        drawFocus(painter, opt, textRect);
    }
}

/*!
    Returns the size needed by the delegate to display the item
    specified by \a index, taking into account the style information