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 <QScrollBar>
  35 #include <QStyle>
  36 #include <QStyleOption>
  37
  38 #include <KDebug>
  39
  40 /**
  41  * Replaces the default viewport of KItemListContainer by a
  42  * non-scrollable viewport. The scrolling is done in an optimized
  43  * way by KItemListView internally.
  44  */
  45 class KItemListContainerViewport : public QGraphicsView
  46 {
  47 public:
  48     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  49 protected:
  50     virtual void wheelEvent(QWheelEvent* event);
  51 };
  52
  53 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  54     QGraphicsView(scene, parent)
  55 {
  56     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  57     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  58     setViewportMargins(0, 0, 0, 0);
  59     setFrameShape(QFrame::NoFrame);
  60 }
  61
  62 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  63 {
  64     // Assure that the wheel-event gets forwarded to the parent
  65     // and not handled at all by QGraphicsView.
  66     event->ignore();
  67 }
  68
  69 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  70     QAbstractScrollArea(parent),
  71     m_controller(controller),
  72     m_horizontalSmoothScroller(0),
  73     m_verticalSmoothScroller(0)
  74 {
  75     Q_ASSERT(controller);
  76     controller->setParent(this);
  77
  78     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  79     setViewport(graphicsView);
  80
  81     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  82     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  83
  84     if (controller->model()) {
  85         slotModelChanged(controller->model(), 0);
  86     }
  87     if (controller->view()) {
  88         slotViewChanged(controller->view(), 0);
  89     }
  90
  91     connect(controller, &KItemListController::modelChanged,
  92             this, &KItemListContainer::slotModelChanged);
  93     connect(controller, &KItemListController::viewChanged,
  94             this, &KItemListContainer::slotViewChanged);
  95 }
  96
  97 KItemListContainer::~KItemListContainer()
  98 {
  99     // Don't rely on the QObject-order to delete the controller, otherwise
 100     // the QGraphicsScene might get deleted before the view.
 101     delete m_controller;
 102     m_controller = 0;
 103 }
 104
 105 KItemListController* KItemListContainer::controller() const
 106 {
 107     return m_controller;
 108 }
 109
 110 void KItemListContainer::setEnabledFrame(bool enable)
 111 {
 112     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 113     if (enable) {
 114         setFrameShape(QFrame::StyledPanel);
 115         graphicsView->setPalette(palette());
 116         graphicsView->viewport()->setAutoFillBackground(true);
 117     } else {
 118         setFrameShape(QFrame::NoFrame);
 119         // Make the background of the container transparent and apply the window-text color
 120         // to the text color, so that enough contrast is given for all color
 121         // schemes
 122         QPalette p = graphicsView->palette();
 123         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 124         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 125         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 126         graphicsView->setPalette(p);
 127         graphicsView->viewport()->setAutoFillBackground(false);
 128     }
 129 }
 130
 131 bool KItemListContainer::enabledFrame() const
 132 {
 133     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 134     return graphicsView->autoFillBackground();
 135 }
 136
 137 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 138 {
 139     // TODO: We should find a better way to handle the key press events in the view.
 140     // The reasons why we need this hack are:
 141     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 142     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 143     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 144     //    does not work.
 145     KItemListView* view = m_controller->view();
 146     if (view) {
 147         QApplication::sendEvent(view, event);
 148     }
 149 }
 150
 151 void KItemListContainer::showEvent(QShowEvent* event)
 152 {
 153     QAbstractScrollArea::showEvent(event);
 154     updateGeometries();
 155 }
 156
 157 void KItemListContainer::resizeEvent(QResizeEvent* event)
 158 {
 159     QAbstractScrollArea::resizeEvent(event);
 160     updateGeometries();
 161 }
 162
 163 void KItemListContainer::scrollContentsBy(int dx, int dy)
 164 {
 165     m_horizontalSmoothScroller->scrollContentsBy(dx);
 166     m_verticalSmoothScroller->scrollContentsBy(dy);
 167 }
 168
 169 void KItemListContainer::wheelEvent(QWheelEvent* event)
 170 {
 171     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 172         event->ignore();
 173         return;
 174     }
 175
 176     KItemListView* view = m_controller->view();
 177     if (!view) {
 178         event->ignore();
 179         return;
 180     }
 181
 182     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 183                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 184     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 185                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 186
 187     const QScrollBar* scrollBar = smoothScroller->scrollBar();
 188     if (!event->pixelDelta().isNull()) {
 189         const int numPixels =  event->pixelDelta().y();
 190         smoothScroller->scrollTo(scrollBar->value() - numPixels);
 191     } else {
 192         const int numDegrees = event->angleDelta().y() / 8;
 193         const int numSteps = numDegrees / 15;
 194         smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep() / 4);
 195     }
 196
 197     event->accept();
 198 }
 199
 200 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 201 {
 202     Q_UNUSED(previous);
 203     updateSmoothScrollers(current);
 204 }
 205
 206 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 207 {
 208     Q_UNUSED(current);
 209     Q_UNUSED(previous);
 210 }
 211
 212 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 213 {
 214     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 215     if (previous) {
 216         scene->removeItem(previous);
 217         disconnect(previous, &KItemListView::scrollOrientationChanged,
 218                    this, &KItemListContainer::slotScrollOrientationChanged);
 219         disconnect(previous, &KItemListView::scrollOffsetChanged,
 220                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 221         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 222                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 223         disconnect(previous, &KItemListView::itemOffsetChanged,
 224                    this, &KItemListContainer::updateItemOffsetScrollBar);
 225         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 226                    this, &KItemListContainer::updateItemOffsetScrollBar);
 227         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 228         m_horizontalSmoothScroller->setTargetObject(0);
 229         m_verticalSmoothScroller->setTargetObject(0);
 230     }
 231     if (current) {
 232         scene->addItem(current);
 233         connect(current, &KItemListView::scrollOrientationChanged,
 234                 this, &KItemListContainer::slotScrollOrientationChanged);
 235         connect(current, &KItemListView::scrollOffsetChanged,
 236                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 237         connect(current, &KItemListView::maximumScrollOffsetChanged,
 238                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 239         connect(current, &KItemListView::itemOffsetChanged,
 240                 this, &KItemListContainer::updateItemOffsetScrollBar);
 241         connect(current, &KItemListView::maximumItemOffsetChanged,
 242                 this, &KItemListContainer::updateItemOffsetScrollBar);
 243         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 244         m_horizontalSmoothScroller->setTargetObject(current);
 245         m_verticalSmoothScroller->setTargetObject(current);
 246         updateSmoothScrollers(current->scrollOrientation());
 247     }
 248 }
 249
 250 void KItemListContainer::scrollTo(qreal offset)
 251 {
 252     const KItemListView* view = m_controller->view();
 253     if (view) {
 254         if (view->scrollOrientation() == Qt::Vertical) {
 255             m_verticalSmoothScroller->scrollTo(offset);
 256         } else {
 257             m_horizontalSmoothScroller->scrollTo(offset);
 258         }
 259     }
 260 }
 261
 262 void KItemListContainer::updateScrollOffsetScrollBar()
 263 {
 264     const KItemListView* view = m_controller->view();
 265     if (!view) {
 266         return;
 267     }
 268
 269     KItemListSmoothScroller* smoothScroller = 0;
 270     QScrollBar* scrollOffsetScrollBar = 0;
 271     int singleStep = 0;
 272     int pageStep = 0;
 273     int maximum = 0;
 274     if (view->scrollOrientation() == Qt::Vertical) {
 275         smoothScroller = m_verticalSmoothScroller;
 276         scrollOffsetScrollBar = verticalScrollBar();
 277         singleStep = view->itemSize().height();
 278         // We cannot use view->size().height() because this height might
 279         // include the header widget, which is not part of the scrolled area.
 280         pageStep = view->verticalPageStep();
 281
 282         // However, the total height of the view must be considered for the
 283         // maximum value of the scroll bar. Note that the view's scrollOffset()
 284         // refers to the offset of the top part of the view, which might be
 285         // hidden behind the header.
 286         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 287     } else {
 288         smoothScroller = m_horizontalSmoothScroller;
 289         scrollOffsetScrollBar = horizontalScrollBar();
 290         singleStep = view->itemSize().width();
 291         pageStep = view->size().width();
 292         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 293     }
 294
 295     const int value = view->scrollOffset();
 296     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 297         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 298                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 299
 300         scrollOffsetScrollBar->setSingleStep(singleStep);
 301         scrollOffsetScrollBar->setPageStep(pageStep);
 302         scrollOffsetScrollBar->setMinimum(0);
 303         scrollOffsetScrollBar->setMaximum(maximum);
 304         scrollOffsetScrollBar->setValue(value);
 305
 306         if (updatePolicy) {
 307             // Prevent a potential endless layout loop (see bug #293318).
 308             updateScrollOffsetScrollBarPolicy();
 309         }
 310     }
 311 }
 312
 313 void KItemListContainer::updateItemOffsetScrollBar()
 314 {
 315     const KItemListView* view = m_controller->view();
 316     if (!view) {
 317         return;
 318     }
 319
 320     KItemListSmoothScroller* smoothScroller = 0;
 321     QScrollBar* itemOffsetScrollBar = 0;
 322     int singleStep = 0;
 323     int pageStep = 0;
 324     if (view->scrollOrientation() == Qt::Vertical) {
 325         smoothScroller = m_horizontalSmoothScroller;
 326         itemOffsetScrollBar = horizontalScrollBar();
 327         singleStep = view->size().width() / 10;
 328         pageStep = view->size().width();
 329     } else {
 330         smoothScroller = m_verticalSmoothScroller;
 331         itemOffsetScrollBar = verticalScrollBar();
 332         singleStep = view->size().height() / 10;
 333         pageStep = view->size().height();
 334     }
 335
 336     const int value = view->itemOffset();
 337     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 338     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 339         itemOffsetScrollBar->setSingleStep(singleStep);
 340         itemOffsetScrollBar->setPageStep(pageStep);
 341         itemOffsetScrollBar->setMinimum(0);
 342         itemOffsetScrollBar->setMaximum(maximum);
 343         itemOffsetScrollBar->setValue(value);
 344     }
 345 }
 346
 347 void KItemListContainer::updateGeometries()
 348 {
 349     QRect rect = geometry();
 350
 351     int extra = frameWidth() * 2;
 352     QStyleOption option;
 353     option.initFrom(this);
 354     int scrollbarSpacing = 0;
 355     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 356         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 357     }
 358
 359     const int widthDec = verticalScrollBar()->isVisible()
 360                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 361                          : extra;
 362
 363     const int heightDec = horizontalScrollBar()->isVisible()
 364                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 365                           : extra;
 366
 367     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 368                              rect.height() - heightDec);
 369     if (m_controller->view()->geometry() != newGeometry) {
 370         m_controller->view()->setGeometry(newGeometry);
 371
 372         // Get the real geometry of the view again since the scrollbars
 373         // visibilities and the view geometry may have changed in re-layout.
 374         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 375         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 376
 377         updateScrollOffsetScrollBar();
 378         updateItemOffsetScrollBar();
 379     }
 380 }
 381
 382 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 383 {
 384     if (orientation == Qt::Vertical) {
 385         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 386         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 387     } else {
 388         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 389         m_verticalSmoothScroller->setPropertyName("itemOffset");
 390     }
 391 }
 392
 393 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 394 {
 395     const KItemListView* view = m_controller->view();
 396     Q_ASSERT(view);
 397     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 398
 399     QStyleOption option;
 400     option.initFrom(this);
 401     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 402
 403     QSizeF newViewSize = m_controller->view()->size();
 404     if (vertical) {
 405         newViewSize.rwidth() += scrollBarInc;
 406     } else {
 407         newViewSize.rheight() += scrollBarInc;
 408     }
 409
 410     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 411                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 412     if (vertical) {
 413         setVerticalScrollBarPolicy(policy);
 414     } else {
 415         setHorizontalScrollBarPolicy(policy);
 416     }
 417 }
 418