kget/ui/kextendableitemdelegate.cpp

   1 /* This file is part of the KDE libraries
   2     Copyright (C) 2006,2007 Andreas Hartmetz (ahartmetz@gmail.com)
   3
   4     This library is free software; you can redistribute it and/or
   5     modify it under the terms of the GNU Library General Public
   6     License as published by the Free Software Foundation; either
   7     version 2 of the License, or (at your option) any later version.
   8
   9     This library is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12     Library General Public License for more details.
  13
  14     You should have received a copy of the GNU Library General Public License
  15     along with this library; see the file COPYING.LIB.  If not, write to
  16     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17     Boston, MA 02110-1301, USA.
  18 */
  19
  20
  21 #include "kextendableitemdelegate.h"
  22 #include <QModelIndex>
  23 #include <QPersistentModelIndex>
  24 #include <QTreeView>
  25 #include <QPainter>
  26 #include <QEvent>
  27 #include <QMouseEvent>
  28 #include <QApplication>
  29
  30 #include <kdebug.h>
  31
  32 //TODO:listen for removal of rows and columns to clean out dead persistent indexes/editors.
  33 //(not needed ATM, the only user is KShortcutsEditor)
  34
  35 class KExtendableItemDelegatePrivate {
  36 public:
  37         //this will trigger a lot of auto-casting QModelIndex <-> QPersistentModelIndex
  38         QHash<QPersistentModelIndex, QWidget *> extenders;
  39         QHash<QWidget *, QPersistentModelIndex> extenderIndices;
  40         QPixmap extendIcon;
  41         QPixmap contractIcon;
  42         //mostly for quick startup - don't look for extenders while the view
  43         //is being populated.
  44         int stateTick;
  45         bool hasExtenders;
  46 };
  47
  48
  49 KExtendableItemDelegate::KExtendableItemDelegate(QAbstractItemView* parent)
  50  : QItemDelegate(parent),
  51    d(new KExtendableItemDelegatePrivate)
  52 {
  53         d->hasExtenders = false;
  54         d->stateTick = 0;
  55         //parent->installEventFilter(this); //not sure if this is good
  56 }
  57
  58
  59 KExtendableItemDelegate::~KExtendableItemDelegate()
  60 {
  61         delete d;
  62 }
  63
  64
  65 void KExtendableItemDelegate::extendItem(QWidget *ext, const QModelIndex &index)
  66 {
  67         if (!ext || !index.isValid())
  68                 return;
  69         //maintain the invariant "zero or one extender per row"
  70         d->stateTick++;
  71         contractItem(indexOfExtendedColumnInSameRow(index));
  72         d->stateTick++;
  73         //reparent, as promised in the docs
  74         QAbstractItemView *aiv = qobject_cast<QAbstractItemView *>(parent());
  75         if (!aiv)
  76                 return;
  77         ext->setParent(aiv->viewport());
  78         d->extenders.insert(index, ext);
  79         d->extenderIndices.insert(ext, index);
  80         d->hasExtenders = true;
  81         connect(ext, SIGNAL(destroyed(QObject *)), this, SLOT(extenderDestructionHandler(QObject *)));
  82         emit extenderCreated(ext, index);
  83         scheduleUpdateViewLayout();
  84 }
  85
  86
  87 void KExtendableItemDelegate::contractItem(const QModelIndex& index)
  88 {
  89         QWidget *extender = d->extenders.value(index);
  90         if (!extender)
  91                 return;
  92
  93         extender->hide();
  94         extender->deleteLater();
  95
  96         scheduleUpdateViewLayout();
  97 }
  98
  99
 100 //slot
 101 void KExtendableItemDelegate::extenderDestructionHandler(QObject *destroyed)
 102 {
 103         QWidget *extender = static_cast<QWidget *>(destroyed);
 104         d->stateTick++;
 105
 106         if(d->extenderIndices.value(extender).isValid()) {
 107             if (receivers(SIGNAL(extenderDestroyed(QWidget *, QModelIndex)))) {
 108                     QPersistentModelIndex persistentIndex = d->extenderIndices.take(extender);
 109                     QModelIndex index = persistentIndex;
 110                     emit extenderDestroyed(extender, index);
 111                     d->extenders.remove(persistentIndex);
 112             } else
 113                     d->extenders.remove(d->extenderIndices.take(extender));
 114
 115             if (d->extenders.isEmpty())
 116                     d->hasExtenders = false;
 117
 118             scheduleUpdateViewLayout();
 119     }
 120 }
 121
 122
 123 bool KExtendableItemDelegate::isExtended(const QModelIndex &index) const {
 124         return d->extenders.value(index);
 125 }
 126
 127
 128 QSize KExtendableItemDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
 129 {
 130         QSize ret;
 131
 132         if (d->hasExtenders)
 133                 ret = maybeExtendedSize(option, index);
 134         else
 135                 ret = QItemDelegate::sizeHint(option, index);
 136
 137         bool showExtensionIndicator = index.model()->data(index, ShowExtensionIndicatorRole).toBool();
 138         if (showExtensionIndicator)
 139                 ret.rwidth() += d->extendIcon.width();
 140
 141         return ret;
 142 }
 143
 144
 145 void KExtendableItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
 146 {
 147         int indicatorX = 0;
 148         int indicatorY = 0;
 149
 150         QStyleOptionViewItem indicatorOption(option);
 151         QStyleOptionViewItem itemOption(option);
 152         bool showExtensionIndicator = index.model()->data(index, ShowExtensionIndicatorRole).toBool();
 153
 154         if (showExtensionIndicator) {
 155                 if (QApplication::isRightToLeft()) {
 156                         indicatorX = option.rect.right() - d->extendIcon.width();
 157                         itemOption.rect.setRight(option.rect.right() - d->extendIcon.width());
 158                         indicatorOption.rect.setLeft(option.rect.right() - d->extendIcon.width());
 159                 }
 160                 else {
 161                         indicatorX = option.rect.left();
 162                         indicatorOption.rect.setRight(option.rect.left() + d->extendIcon.width());
 163                         itemOption.rect.setLeft(option.rect.left() + d->extendIcon.width());
 164                 }
 165                 indicatorY = option.rect.top() + ((option.rect.height() - d->extendIcon.height()) >> 1);
 166         }
 167
 168         //fast path
 169         if (!d->hasExtenders) {
 170                 QItemDelegate::paint(painter, itemOption, index);
 171                 if (showExtensionIndicator) {
 172                         QItemDelegate::drawBackground(painter, indicatorOption, index);
 173                         painter->drawPixmap(indicatorX, indicatorY,  d->extendIcon);
 174                 }
 175                 return;
 176         }
 177
 178         //indexOfExtendedColumnInSameRow() is very expensive, try to avoid calling it.
 179         static int cachedStateTick = -1;
 180         static int cachedRow = -20; //Qt uses -1 for invalid indices
 181         static QModelIndex cachedParentIndex;
 182         static QWidget *extender = 0;
 183         static int extenderHeight;
 184         int row = index.row();
 185         QModelIndex parentIndex = index.parent();
 186
 187         if (row != cachedRow || cachedStateTick != d->stateTick
 188                 || cachedParentIndex != parentIndex) {
 189                 extender = d->extenders.value(indexOfExtendedColumnInSameRow(index));
 190                 cachedStateTick = d->stateTick;
 191                 cachedRow = row;
 192                 cachedParentIndex = parentIndex;
 193                 if (extender) {
 194                         extenderHeight = extender->sizeHint().height();
 195                 }
 196         }
 197
 198         if (!extender) {
 199                 QItemDelegate::paint(painter, itemOption, index);
 200                 if (showExtensionIndicator) {
 201                         QItemDelegate::drawBackground(painter, indicatorOption, index);
 202                         painter->drawPixmap(indicatorX, indicatorY, d->extendIcon);
 203                 }
 204                 return;
 205         }
 206
 207         //an extender is present - make two rectangles: one to paint the original item, one for the extender
 208         if (isExtended(index)) {
 209                 QStyleOptionViewItem extOption(option);
 210                 extOption.rect = extenderRect(extender, option, index);
 211                 updateExtenderGeometry(extender, extOption, index);
 212                 //if we show it before, it will briefly flash in the wrong location.
 213                 //the downside is, of course, that an api user effectively can't hide it.
 214                 extender->show();
 215         }
 216
 217         indicatorOption.rect.setHeight(option.rect.height() - extenderHeight);
 218         itemOption.rect.setHeight(option.rect.height() - extenderHeight);
 219         //tricky:make sure that the modified options' rect really has the
 220         //same height as the unchanged option.rect if no extender is present
 221         //(seems to work OK)
 222         QItemDelegate::paint(painter, itemOption, index);
 223
 224         if (showExtensionIndicator) {
 225                 //indicatorOption's height changed, change this too
 226                 indicatorY = indicatorOption.rect.top() + ((indicatorOption.rect.height() - d->extendIcon.height()) >> 1);
 227                 QItemDelegate::drawBackground(painter, indicatorOption, index);
 228
 229                 if (d->extenders.contains(index))
 230                         painter->drawPixmap(indicatorX, indicatorY, d->contractIcon);
 231                 else
 232                         painter->drawPixmap(indicatorX, indicatorY, d->extendIcon);
 233         }
 234 }
 235
 236
 237 QRect KExtendableItemDelegate::extenderRect(QWidget *extender, const QStyleOptionViewItem &option, const QModelIndex &index) const
 238 {
 239         Q_ASSERT(extender);
 240         QRect rect(option.rect);
 241         rect.setTop(rect.bottom() + 1 - extender->sizeHint().height());
 242
 243         rect.setLeft(0);
 244         QTreeView *tv = qobject_cast<QTreeView *>(parent());
 245         if (tv)
 246                 for (QModelIndex idx(index.parent()); idx.isValid(); idx = idx.parent())
 247                         rect.translate(tv->indentation(), 0);
 248
 249         QAbstractScrollArea *container = qobject_cast<QAbstractScrollArea *>(parent());
 250         Q_ASSERT(container);
 251         rect.setRight(container->viewport()->width() - 1);
 252         return rect;
 253 }
 254
 255
 256 QSize KExtendableItemDelegate::maybeExtendedSize(const QStyleOptionViewItem &option, const QModelIndex &index) const
 257 {
 258         QWidget *extender = d->extenders.value(index);
 259         QSize size(QItemDelegate::sizeHint(option, index));
 260         if (!extender)
 261                 return size;
 262
 263         //add extender height to maximum height of any column in our row
 264         int itemHeight = size.height();
 265
 266         int row = index.row();
 267         int thisColumn = index.column();
 268         QModelIndex parentIndex(index.parent());
 269
 270         //this is quite slow, but Qt is smart about when to call sizeHint().
 271         for (int column=0;column<6; column++) {
 272                 if (column == thisColumn)
 273                         continue;
 274
 275                 QModelIndex neighborIndex(index.sibling(row, column));
 276                 if (!neighborIndex.isValid())
 277                         break;
 278                 itemHeight = qMax(itemHeight, QItemDelegate::sizeHint(option, neighborIndex).height());
 279         }
 280
 281         //we only want to reserve vertical space
 282         size.rheight() = itemHeight + extender->sizeHint().height();
 283         return size;
 284 }
 285
 286
 287 QModelIndex KExtendableItemDelegate::indexOfExtendedColumnInSameRow(const QModelIndex &index) const
 288 {
 289         const QAbstractItemModel *const model = index.model();
 290         const QModelIndex parentIndex(index.parent());
 291         const int row = index.row();
 292         const int columnCount = model->columnCount();
 293
 294         //slow, slow, slow
 295         for (int column = 0; column < columnCount; column++) {
 296                 QModelIndex indexOfExt(model->index(row, column, parentIndex));
 297                 if (d->extenders.value(indexOfExt))
 298                         return indexOfExt;
 299         }
 300
 301         return QModelIndex();
 302 }
 303
 304
 305 void KExtendableItemDelegate::updateExtenderGeometry(QWidget *extender, const QStyleOptionViewItem &option, const QModelIndex &index) const
 306 {
 307         Q_UNUSED(index);
 308         extender->setGeometry(option.rect);
 309 }
 310
 311
 312 //make the view re-ask for sizeHint() and redisplay items with their new size
 313 void KExtendableItemDelegate::scheduleUpdateViewLayout() const
 314 {
 315         QAbstractItemView *aiv = qobject_cast<QAbstractItemView *>(parent());
 316         //prevent crashes during destruction of the view
 317         if (aiv)
 318                 //dirty hack to call aiv's protected scheduleDelayedItemsLayout()
 319                 aiv->setRootIndex(aiv->rootIndex());
 320 }
 321
 322
 323 void KExtendableItemDelegate::setExtendIcon(const QPixmap &icon)
 324 {
 325         d->extendIcon = icon;
 326 }
 327
 328
 329 void KExtendableItemDelegate::setContractIcon(const QPixmap &icon)
 330 {
 331         d->contractIcon = icon;
 332 }
 333
 334
 335 QPixmap KExtendableItemDelegate::extendIcon()
 336 {
 337         return d->extendIcon;
 338 }
 339
 340
 341 QPixmap KExtendableItemDelegate::contractIcon()
 342 {
 343         return d->contractIcon;
 344 }
 345
 346 #include "kextendableitemdelegate.moc"