src/kitemviews/kitemlistcontainer.cpp

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   Based on the Itemviews NG project from Trolltech Labs:                *
   5  *   http://qt.gitorious.org/qt-labs/itemviews-ng                          *
   6  *                                                                         *
   7  *   This program is free software; you can redistribute it and/or modify  *
   8  *   it under the terms of the GNU General Public License as published by  *
   9  *   the Free Software Foundation; either version 2 of the License, or     *
  10  *   (at your option) any later version.                                   *
  11  *                                                                         *
  12  *   This program is distributed in the hope that it will be useful,       *
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  15  *   GNU General Public License for more details.                          *
  16  *                                                                         *
  17  *   You should have received a copy of the GNU General Public License     *
  18  *   along with this program; if not, write to the                         *
  19  *   Free Software Foundation, Inc.,                                       *
  20  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  21  ***************************************************************************/
  22
  23 #include "kitemlistcontainer.h"
  24
  25 #include "kitemlistcontroller.h"
  26 #include "kitemlistview.h"
  27 #include "kitemmodelbase.h"
  28
  29 #include "private/kitemlistsmoothscroller.h"
  30
  31 #include <QApplication>
  32 #include <QGraphicsScene>
  33 #include <QGraphicsView>
  34 #include <QPropertyAnimation>
  35 #include <QScrollBar>
  36 #include <QStyle>
  37 #include <QStyleOption>
  38
  39 #include <KDebug>
  40
  41 /**
  42  * Replaces the default viewport of KItemListContainer by a
  43  * non-scrollable viewport. The scrolling is done in an optimized
  44  * way by KItemListView internally.
  45  */
  46 class KItemListContainerViewport : public QGraphicsView
  47 {
  48 public:
  49     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  50 protected:
  51     virtual void wheelEvent(QWheelEvent* event);
  52 };
  53
  54 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  55     QGraphicsView(scene, parent)
  56 {
  57     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  58     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  59     setViewportMargins(0, 0, 0, 0);
  60     setFrameShape(QFrame::NoFrame);
  61 }
  62
  63 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  64 {
  65     // Assure that the wheel-event gets forwarded to the parent
  66     // and not handled at all by QGraphicsView.
  67     event->ignore();
  68 }
  69
  70 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  71     QAbstractScrollArea(parent),
  72     m_controller(controller),
  73     m_horizontalSmoothScroller(0),
  74     m_verticalSmoothScroller(0)
  75 {
  76     Q_ASSERT(controller);
  77     controller->setParent(this);
  78
  79     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  80     setViewport(graphicsView);
  81
  82     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  83     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  84
  85     if (controller->model()) {
  86         slotModelChanged(controller->model(), 0);
  87     }
  88     if (controller->view()) {
  89         slotViewChanged(controller->view(), 0);
  90     }
  91
  92     connect(controller, SIGNAL(modelChanged(KItemModelBase*,KItemModelBase*)),
  93             this, SLOT(slotModelChanged(KItemModelBase*,KItemModelBase*)));
  94     connect(controller, SIGNAL(viewChanged(KItemListView*,KItemListView*)),
  95             this, SLOT(slotViewChanged(KItemListView*,KItemListView*)));
  96 }
  97
  98 KItemListContainer::~KItemListContainer()
  99 {
 100     // Don't rely on the QObject-order to delete the controller, otherwise
 101     // the QGraphicsScene might get deleted before the view.
 102     delete m_controller;
 103     m_controller = 0;
 104 }
 105
 106 KItemListController* KItemListContainer::controller() const
 107 {
 108     return m_controller;
 109 }
 110
 111 void KItemListContainer::setEnabledFrame(bool enable)
 112 {
 113     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 114     if (enable) {
 115         setFrameShape(QFrame::StyledPanel);
 116         graphicsView->setPalette(palette());
 117         graphicsView->viewport()->setAutoFillBackground(true);
 118     } else {
 119         setFrameShape(QFrame::NoFrame);
 120         // Make the background of the container transparent and apply the window-text color
 121         // to the text color, so that enough contrast is given for all color
 122         // schemes
 123         QPalette p = graphicsView->palette();
 124         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 125         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 126         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 127         graphicsView->setPalette(p);
 128         graphicsView->viewport()->setAutoFillBackground(false);
 129     }
 130 }
 131
 132 bool KItemListContainer::enabledFrame() const
 133 {
 134     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 135     return graphicsView->autoFillBackground();
 136 }
 137
 138 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 139 {
 140     // TODO: We should find a better way to handle the key press events in the view.
 141     // The reasons why we need this hack are:
 142     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 143     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 144     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 145     //    does not work.
 146     KItemListView* view = m_controller->view();
 147     if (view) {
 148         QApplication::sendEvent(view, event);
 149     }
 150 }
 151
 152 void KItemListContainer::showEvent(QShowEvent* event)
 153 {
 154     QAbstractScrollArea::showEvent(event);
 155     updateGeometries();
 156 }
 157
 158 void KItemListContainer::resizeEvent(QResizeEvent* event)
 159 {
 160     QAbstractScrollArea::resizeEvent(event);
 161     updateGeometries();
 162 }
 163
 164 void KItemListContainer::scrollContentsBy(int dx, int dy)
 165 {
 166     m_horizontalSmoothScroller->scrollContentsBy(dx);
 167     m_verticalSmoothScroller->scrollContentsBy(dy);
 168 }
 169
 170 void KItemListContainer::wheelEvent(QWheelEvent* event)
 171 {
 172     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 173         event->ignore();
 174         return;
 175     }
 176
 177     KItemListView* view = m_controller->view();
 178     if (!view) {
 179         event->ignore();
 180         return;
 181     }
 182
 183     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 184                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 185     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 186                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 187
 188     const int numDegrees = event->delta() / 8;
 189     const int numSteps = numDegrees / 15;
 190
 191     const QScrollBar* scrollBar = smoothScroller->scrollBar();
 192     smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 4);
 193
 194     event->accept();
 195 }
 196
 197 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 198 {
 199     Q_UNUSED(previous);
 200     updateSmoothScrollers(current);
 201 }
 202
 203 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 204 {
 205     Q_UNUSED(current);
 206     Q_UNUSED(previous);
 207 }
 208
 209 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 210 {
 211     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 212     if (previous) {
 213         scene->removeItem(previous);
 214         disconnect(previous, SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
 215         disconnect(previous, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, SLOT(updateScrollOffsetScrollBar()));
 216         disconnect(previous, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, SLOT(updateScrollOffsetScrollBar()));
 217         disconnect(previous, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, SLOT(updateItemOffsetScrollBar()));
 218         disconnect(previous, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, SLOT(updateItemOffsetScrollBar()));
 219         disconnect(previous, SIGNAL(scrollTo(qreal)),                         this, SLOT(scrollTo(qreal)));
 220         m_horizontalSmoothScroller->setTargetObject(0);
 221         m_verticalSmoothScroller->setTargetObject(0);
 222     }
 223     if (current) {
 224         scene->addItem(current);
 225         connect(current, SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
 226         connect(current, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, SLOT(updateScrollOffsetScrollBar()));
 227         connect(current, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, SLOT(updateScrollOffsetScrollBar()));
 228         connect(current, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, SLOT(updateItemOffsetScrollBar()));
 229         connect(current, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, SLOT(updateItemOffsetScrollBar()));
 230         connect(current, SIGNAL(scrollTo(qreal)),                         this, SLOT(scrollTo(qreal)));
 231         m_horizontalSmoothScroller->setTargetObject(current);
 232         m_verticalSmoothScroller->setTargetObject(current);
 233         updateSmoothScrollers(current->scrollOrientation());
 234     }
 235 }
 236
 237 void KItemListContainer::scrollTo(qreal offset)
 238 {
 239     const KItemListView* view = m_controller->view();
 240     if (view) {
 241         if (view->scrollOrientation() == Qt::Vertical) {
 242             m_verticalSmoothScroller->scrollTo(offset);
 243         } else {
 244             m_horizontalSmoothScroller->scrollTo(offset);
 245         }
 246     }
 247 }
 248
 249 void KItemListContainer::updateScrollOffsetScrollBar()
 250 {
 251     const KItemListView* view = m_controller->view();
 252     if (!view) {
 253         return;
 254     }
 255
 256     KItemListSmoothScroller* smoothScroller = 0;
 257     QScrollBar* scrollOffsetScrollBar = 0;
 258     int singleStep = 0;
 259     int pageStep = 0;
 260     int maximum = 0;
 261     if (view->scrollOrientation() == Qt::Vertical) {
 262         smoothScroller = m_verticalSmoothScroller;
 263         scrollOffsetScrollBar = verticalScrollBar();
 264         singleStep = view->itemSize().height();
 265         // We cannot use view->size().height() because this height might
 266         // include the header widget, which is not part of the scrolled area.
 267         pageStep = view->verticalPageStep();
 268
 269         // However, the total height of the view must be considered for the
 270         // maximum value of the scroll bar. Note that the view's scrollOffset()
 271         // refers to the offset of the top part of the view, which might be
 272         // hidden behind the header.
 273         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 274     } else {
 275         smoothScroller = m_horizontalSmoothScroller;
 276         scrollOffsetScrollBar = horizontalScrollBar();
 277         singleStep = view->itemSize().width();
 278         pageStep = view->size().width();
 279         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 280     }
 281
 282     const int value = view->scrollOffset();
 283     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 284         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 285                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 286
 287         scrollOffsetScrollBar->setSingleStep(singleStep);
 288         scrollOffsetScrollBar->setPageStep(pageStep);
 289         scrollOffsetScrollBar->setMinimum(0);
 290         scrollOffsetScrollBar->setMaximum(maximum);
 291         scrollOffsetScrollBar->setValue(value);
 292
 293         if (updatePolicy) {
 294             // Prevent a potential endless layout loop (see bug #293318).
 295             updateScrollOffsetScrollBarPolicy();
 296         }
 297     }
 298 }
 299
 300 void KItemListContainer::updateItemOffsetScrollBar()
 301 {
 302     const KItemListView* view = m_controller->view();
 303     if (!view) {
 304         return;
 305     }
 306
 307     KItemListSmoothScroller* smoothScroller = 0;
 308     QScrollBar* itemOffsetScrollBar = 0;
 309     int singleStep = 0;
 310     int pageStep = 0;
 311     if (view->scrollOrientation() == Qt::Vertical) {
 312         smoothScroller = m_horizontalSmoothScroller;
 313         itemOffsetScrollBar = horizontalScrollBar();
 314         singleStep = view->size().width() / 10;
 315         pageStep = view->size().width();
 316     } else {
 317         smoothScroller = m_verticalSmoothScroller;
 318         itemOffsetScrollBar = verticalScrollBar();
 319         singleStep = view->size().height() / 10;
 320         pageStep = view->size().height();
 321     }
 322
 323     const int value = view->itemOffset();
 324     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 325     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 326         itemOffsetScrollBar->setSingleStep(singleStep);
 327         itemOffsetScrollBar->setPageStep(pageStep);
 328         itemOffsetScrollBar->setMinimum(0);
 329         itemOffsetScrollBar->setMaximum(maximum);
 330         itemOffsetScrollBar->setValue(value);
 331     }
 332 }
 333
 334 void KItemListContainer::updateGeometries()
 335 {
 336     QRect rect = geometry();
 337
 338     int extra = frameWidth() * 2;
 339     QStyleOption option;
 340     option.initFrom(this);
 341     int scrollbarSpacing = 0;
 342     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 343         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 344     }
 345
 346     const int widthDec = verticalScrollBar()->isVisible()
 347                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 348                          : extra;
 349
 350     const int heightDec = horizontalScrollBar()->isVisible()
 351                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 352                           : extra;
 353
 354     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 355                              rect.height() - heightDec);
 356     if (m_controller->view()->geometry() != newGeometry) {
 357         m_controller->view()->setGeometry(newGeometry);
 358
 359         // Get the real geometry of the view again since the scrollbars
 360         // visibilities and the view geometry may have changed in re-layout.
 361         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 362         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 363
 364         updateScrollOffsetScrollBar();
 365         updateItemOffsetScrollBar();
 366     }
 367 }
 368
 369 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 370 {
 371     if (orientation == Qt::Vertical) {
 372         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 373         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 374     } else {
 375         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 376         m_verticalSmoothScroller->setPropertyName("itemOffset");
 377     }
 378 }
 379
 380 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 381 {
 382     const KItemListView* view = m_controller->view();
 383     Q_ASSERT(view);
 384     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 385
 386     QStyleOption option;
 387     option.initFrom(this);
 388     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 389
 390     QSizeF newViewSize = m_controller->view()->size();
 391     if (vertical) {
 392         newViewSize.rwidth() += scrollBarInc;
 393     } else {
 394         newViewSize.rheight() += scrollBarInc;
 395     }
 396
 397     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 398                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 399     if (vertical) {
 400         setVerticalScrollBarPolicy(policy);
 401     } else {
 402         setHorizontalScrollBarPolicy(policy);
 403     }
 404 }
 405
 406 #include "kitemlistcontainer.moc"